Past Colloquia in Physics & Astronomy

IS QUANTUM THEORY EXACT?
Collapse models and the possibility of a breakdown of quantum mechanics towards the macroscopic scale

   Angelo Bassi  

University of Trieste

11 May 2012  

This talk will review the problems quantum mechanics encounters when describing measurement situations (more generally, the quantum-to-classical transition) and the solutions which have been proposed so far. Dr Bassi will focus on one such solution: models of spontaneous wave function collapse. He will describe their general features and discuss the lower and upper bounds on their parameters, before reviewing their status as phenomenological modifications of quantum mechanics, whose predictions can be tested experimentally.

COSMOLOGY IN OUR BACKYARD

   Carlos Frenk  

Durham University

4 May 2012  

The LCDM cosmological model accounts for an impressive array of data on the large-scale structure of the universe. On submegaparsec scales, however, the model cannot be tested with the same degree of rigour as on larger scales where microwave background radiation data and measures of galaxy clustering provide clean and well-understood diagnostics. Yet, it is precisely on these small scales that the nature of the dark matter manifests itself most clearly. Prof Frenk will discuss theoretical predictions for the small-scale structure of the universe which appear to be discrepant with recent kinematical data for satellite galaxies of the Milky Way. Possible solutions range from exotic baryonic processes to the more radical assumption that the dark matter is not what the standard theory assumes.

NANOPLASMONIC FIELD-ENHANCED HIGH HARMONIC GENERATION AT MHz REPETITION RATES

   Sarah Stebbings  

Max Planck Institute for Quantum Optics

27 April 2012  

Laser driven high harmonic generation is a well established technique for the production of attosecond pulses in the extreme ultraviolet (XUV). In this talk, Dr Stebbings will present the different approaches employed in order to generate trains of and isolated attosecond XUV pulses at MHz repetition rates. These sources have potential to open up new applications in lithography, nanoplasmonics, high-precision spectroscopy and time-resolved coincidence experiments.

QUANTUM NANOPHOTONICS

   Peter Lodahl  

University of Copenhagen

20 April 2012  

Nanophotonics structures such as photonic crystals or plasmon nanostructures have in recent years proven to provide a very efficient way of enhancing the local interaction between light and matter enabling all-solid-state quantum electrodynamics experiments. This talk will review recent progress on 2D photonic crystal membranes containing quantum dots for photon emission control, and discuss how a highly efficient and triggered single-photon source can be constructed by coupling single quantum dots to a photonic crystal waveguide by exploiting slow light. The role of disorder in the form of fabrication imperfections is explored and found to lead to Anderson localization of light enabling cavity quantum electrodynamics by exploiting disorder as a way to enhance light-matter interactions. Finally, it will be demonstrated that the mesoscopic character of quantum dot emitters implies that the traditional point-dipole description of light-matter interaction may break down in plasmonic nanostructures, providing a new way to strongly interface photons with matter.

PEPTIDE-FUNCTIONALISED NANOMATERIALS FOR BIOSENSING AND OTHER APPLICATIONS

   Molly Stevens  

Imperial College, London

9 March 2012  

This talk will cover the Imperial College group's recent work in the design of peptide-functionalised nanoparticles responsive to a plethora of different enzymes. Self-assembling materials can also be utilised successfully in regenerative medicine as will be illustrated here.

ORGANIC SEMICONDUCTORS: LIGHTING UP THE FUTURE

   Ifor Samuel  

University of St Andrews

2 March 2012  

Organic semiconductors are of growing importance as optoelectronic materials. This talk will introduce the materials and show examples of emerging applications. These include the use of organic light-emitting diodes to enable skin cancer treatment, and the detection of explosive vapour using organic semiconductor lasers.

POSITRON ANNIHILATION IN MOLECULES

   Gleb Gribakin  

Queen's University, Belfast

24 February 2012  

It has been known since 1950's that positron annihilation rates in many polyatomic molecules can be orders of magnitude greater than estimates based on Dirac's electron-positron annihilation rate. This phenomenon remained one of the major puzzles of positron physics for decades. Dr Gribakin's talk will review the results of concerted efforts by experiment and theory over the past ten years, which have provided much understanding and revealed many interesting details.
As we now know, the enhancement of positron annihilation is caused by positron capture in vibrational Feshbach resonances. This capture is facilitated by the ability of the positron to bind to many neutral atomic and molecular species. The annihilation probability is further enhanced by processes of intramolecular vibrational energy redistribution which increases the positron resonant trapping time.

NOVEL ION TRAPS FOR DETERMINISTIC ION IMPLANTATION AND QUANTUM SIMULATION

   Kilian Singer  

University of Mainz

17 February 2012  

Novel geometries of ion traps allow the deterministic, high resolution implantation of individual laser-cooled ions, and can operate with a huge range of sympathetically cooled ion species, isotopes or ionic molecules. They therefore offer the basis of an atomic nano-assembler - a novel device capable of placing an exactly defined number of atoms or molecules with millikelvin energies into solid state substrates with sub-nanometre precision in depth and lateral position.
Motivated by the general quest for novel tailored solid-state quantum materials, the Mainz group's major goal is the deterministic generation of colour centres or quantum dots that can be placed in special geometries to exploit their mutual coupling for the realization of macroscopic functional systems and interfaced to the macroscopic world with the help of electrode structures, single electron transistors and optical micro-cavities. Current state-of-the-art production techniques are incapable of such structures, posing a major production problem for the realization of scaled solid-state quantum devices. Targeted applications range from quantum repeaters, correlated triggered multi-photon sources and calibrated single photon sources to quantum computation circuits and sensors with unprecedented sensitivity.
Dr Singer will also present new planar and three-dimensional trap geometries which allow for the application of variable rf fields for precise positioning of ions in two dimensions. These geometries are of great interest for realizing two-dimensional ion crystals with controllable interactions, and enable novel schemes for the quantum simulation of solid-state spin systems with laser-cooled trapped ions. Dr Singer will also present a novel trap design for the realization of a thermodynamic heat engine with a single ion; simulations and the experimental setup will be shown.

SATELLITE-BASED RESEARCH ON PLANETARY WAVES IN THE OCEAN

   Paolo Cipollini  

National Oceanography Centre, University of Southampton

10 February 2012  

We know from Carl-Gustav Rossby's 1930s theory of planetary waves that they should exist not only in the atmosphere (where they are easily seen) but also in the oceans. However, until the advent of precise satellite altimetry in the 1990s, there was very scarce observational evidence. Altimetry has confirmed that these long-wavelength, westward-propagating internal waves are common in the tropical and mid-latitude ocean, where they accompany the ubiquitous non-linear eddies, and that they travel faster than expected – so theoreticians have had to make some adjustments to the theory. But then we started looking in other global satellite-derived datasets (SST, ocean colour), and the signature of eddies and waves is also clearly visible there - implying that these westward-propagating phenomena affect the heat balance and the biology. All these new observations have opened a number of intriguing questions that are not only important for our full understanding of ocean dynamics, but also linked to climate change and the carbon cycle.
In this talk, Dr Cipollini will review what we know, explain what are the many issues still open in this field of research, that need to be tackled with an integrated, interdisciplinary effort, and provide an update on recent work carried out at the National Oceanography Centre on this topic.

NEXT-GENERATION QUANTUM COMPUTERS

   Mike Brownnutt  

University of Innsbruck

20 January 2012  

Schrödinger bemoaned the fact that one could never perform experiments on single atoms. Nonetheless, in the 20 years since quantum computing was first proposed we have shown that we can actually do exactly that; we have superb control of single atoms, and can perform a variety of basic computational operations on them. Unfortunately, we now face the inverse problem: a computer does consist of single atoms, but of many hundreds or thousands of atoms (at least)! After reviewing how far quantum computing has been carried to date using trapped ions, Dr Brownnutt will look at the question, “Where do we go from here?” What steps must be taken to take the “ridiculous consequences” of quantum mechanics which Schrödinger feared, and preserve them even as we scale computers to such sizes that they are useful? Achieving this scaling in trapped-ion systems requires a radical rethink of how we make and operate traps, but will pave the way to the next generation of quantum computers.

PHYSICS MEETS BIOLOGY: THE PHYSICAL PROPERTIES OF THE CELL MEMBRANE

   Peter Winlove  

University of Exeter

13 January 2012  

Research at the interface between physical science and biology is developing rapidly and studies on the cell membrane demonstrate the importance of this multidisciplinary approach. The textbook view of the membrane as “proteins floating in a sea of phospholipids” (Singer and Nicholson (1970)) fails to address important issues such as the diversity of lipids found in the membrane. We shall begin by discussing studies on Langmuir monolayers of phospholipids which explore the physics of interactions between lipid classes and with cytoskeletal proteins. We shall then introduce novel techniques for measuring the unique mechanical properties of the membrane and present evidence of changes in red cell mechanics that may be important in disease. Finally we shall discuss the complex electrical properties of the membrane, their characterisation by means of fluorescence microscopy, and their importance in membrane function and dysfunction.

SINGLE-SITE-RESOLVED DETECTION AND MANIPULATION OF ATOMS IN AN OPTICAL LATTICE

   Stefan Kuhr  

University of Strathclyde

16 December 2011  

Ultracold atoms in optical lattices are a versatile tool to investigate fundamental properties of quantum many body systems. Prof Kuhr will demonstrate how the control of such systems can be extended down to the most fundamental level of single atomic spins at specific lattice sites. Using a high-resolution optical imaging system, fluorescence images have been obtained of strongly interacting bosonic Mott insulators with single-atom and single-site resolution and addressed the atomic spins with sub-diffraction-limited resolution. In addition, the tunneling quantum dynamics of single atoms in the lattice have been directly monitored. Most recent experiments involve the observation of quantum-correlated particle hole pairs and spreading of correlations after a parameter quench. These results open the path to a wide range of novel applications from quantum dynamics of spin impurities, entropy transport, implementation of novel cooling schemes, and engineering of quantum many-body phases to quantum information processing.

NANOPLASMONICS: FUNDAMENTALS & APPLICATIONS

   Stefan Maier  

Imperial College, London

2 December 2011  

This talk will give an overview over recent research in the Nanoplasmonics group at Imperial College London. The first part will focus of fundamental investigations of localised plasmons in metallic nano particles, in particular approaching the quantum limit with nano antennas, non-local effects, and the creation of broadband light harvesters using transformation optics. The second part of the seminar will discuss applied studies in photovoltaics, biosensing, and a new application of plasmonic – plasmonic sinks for the selective removal of unwanted states in nanoscale light emitters.

QUATERNARY NANOCRYSTALS: SYNTHESIS AND ENERGY APPLICATIONS

   Andreu Cabot  

University of Barcelona and
Catalonia Institute for Energy Research

25 November 2011  

The control of material composition at the nanoscale is essential to the optimization of the characteristics of novel nanomaterials and their performance in applications such as photovoltaics, catalysis and thermoelectrics. In bottom-up synthesis aproaches, nanocrystal composition is determined by the thermodynamics and reaction kinetics of the different precursors, with self-diffusivity playing a key role.
Colloidal synthesis has proved a successful method of obtaining elemental and binary nanocrystals with controlled size and shape distributions, but ternary and quaternary nanocrystals remain a challenge. Dr Cabot will describe current efforts to achieve this step-change in the chemical and structural engineering of functional nanomaterials, which promises to open up the technological potential of quaternary chalcogenides in a range of photonic, optoelectronic, magnetic and chemical applications.

MEASURING HOTTER THAN THE CENTRE OF THE SUN:
DIAGNOSING THE TEMPERATURE OF THE ITER PLASMA

   Graham Naylor  

Culham Centre for Fusion Research

18 November 2011  

The surface of the sun has a temperature of about 6 thousand Kelvin, and its centre is estimated to be at around 15 million Kelvin; in comparison, the centre of the plasma of the International Thermonuclear Experimental Reactor (ITER) is expected to be several hundred million Kelvin. How can this be measured? Laser Thomson Scattering is used routinely around the world to measure the temperature of tokamak plasmas and is expected to be used on ITER but on a scale never achieved before.

GRAPHENE FOR PHOTONICS AND OPTOELECTRONICS

   Andrea Ferrari  

University of Cambridge

11 November 2011  

The richness of optical and electronic properties of graphene attracts enormous interest. Graphene has high mobility and optical transparency, in addition to flexibility, robustness and environmental stability. It has great potential for photonics and optoelectronics, where the combination of its unique optical and electronic properties can be fully exploited, even in the absence of a bandgap, and the linear dispersion of the Dirac electrons enables ultra-wide-band tunability.
Despite being a single atom thick, graphene can be optically visualized. Its transmittance can be expressed in terms of the fine structure constant. The linear dispersion of the Dirac electrons enables broadband applications. Saturable absorption is observed as a consequence of Pauli blocking. Chemical and physical treatments enable luminescence. Graphene-polymer composites can be integrated in laser cavities, to generate ultrafast pulses, to below 200fs, with broadband tunability.

FLEXIBLE, NANOFABRICATED PHOTONIC CRYSTALS: A NEW CLASS OF MICROMECHANICAL ACTUATOR

   James Bateman  

University of Southampton

28 October 2011  

Optical tweezers allow precise and delicate control of tiny objects from atoms to biological cells, yet they require intense light and tight focusing. In micro-optics, light is confined by near wavelength-scale structures, and these steep intensity gradients occur automatically. Coupled with optical resonators, which cause the field to build-up within the structure, we can engineer in microfabricated structures the ideal conditions for strong optical forces.
This combination of tweezing and microfabrication has spawned the rapidly growing field of optomechanics: toroidal resonators coupled evanescently to waveguides have allowed for table-top frequency combs, and vibrating photonic crystals have been cooled to their quantum-mechanical ground state. Despite the enormous scope of optomechanics, work has thus far been confined to the perturbative regime, where structures move only fractionally from their rest positions: mechanical motion is either an intermediary to affect the light, or is used for quantum mechanical demonstrations. This contrasts starkly with MEMS - micro-electromechanical systems - where microstructures move in response to applied voltages to provide technologically useful real world devices.
Dr Bateman will describe work towards creating an optically-driven equivalent of MEMS: micromechanical devices controlled and driven by light. This new class of microactuator will compliment MEMS in, for example, microfluidics, and it hints at far wider possibilities: freed from the electrical connections which tether MEMS to a substrate, we might create biologically-inspired peristaltic pumps, or even freely-floating microswimmers.

ATOM CHIPS: WHERE QUANTUM OPTICS MEETS MATERIAL SCIENCE

   Ron Folman  

Ben Gurion University

14 October 2011  

In this talk, Prof Folman will review the basics of a device called the atom chip in which quantum systems (e.g. ultra cold atoms) are trapped and manipulated microns from the classical environment of a room temperature surface. He will describe the underlying physics governing this combined apparatus (e.g. coupling through the highest temperature gradient ever created in a lab). All this will be detailed in the context of material science which allows engineering of the surface environment so as to accommodate fundamental studies as well as technological applications.

EVIDENCE FOR A COSMIC BATTERY

   Denise Gabuzda  

University College, Cork

7 October 2011  

In a standard theoretical picture of the formation and launching of astrophysical jets, the jets should acquire helical magnetic fields, due essentially to the combination of the rotation of the central black hole and accretion disk and the jet outflow. One way such helical fields may be manifest is through their tendency to give rise to gradients in the observed local Faraday rotation across the jet, due to the systematic variation of the line-of-sight component of the helical magnetic field across the jet. Indeed, transverse Faraday rotation gradients have been observed across a number of AGN jets on both parsec and kiloparsec scales, providing direct evidence that they carry toroidal or helical magnetic fields.
The directions of the observed transverse Faraday rotation gradients provide statistical evidence for the operation of a cosmic "battery" in the accretion disks of AGN, which couples the direction of rotation and the direction of the poloidal (axial) field of the jet. If this "battery" is indeed operating, we have detected the presence of ordered currents and magnetic fields on a grand scale.

A LARGE, DIRTY, MESSY QUANTUM WORLD?

   Mauro Paternostro  

Queen's University, Belfast

30 September 2011  

Quantum mechanics is difficult. Even the most experienced among us will admit the undeniable truth of this claim. Yet, the quantum framework is endowed with such a degree of accuracy that it has embodied a genuine conceptual revolution in the way we explain and understand Nature at the microscopic and level.
By adopting an information-theoretical viewpoint, Dr Paternostro will in this talk discuss the possibility to extend the applicability of quantum theory up to the point that inherently complicated systems, trespassing the boundaries of the clean and protected micro-world, can exhibit truly quantum features, thus entering what may be called "the mesoscopic quantum domain".
Dr Paternostro will discuss in depth the technological implications of such a paradigm shift and demonstrate that the control that is currently available in photonics and condensed-matter labs is indeed sufficient to build an experimental programme for the demonstration of a "larger, dirtier and messier quantum world"!

THE SQUARE KILOMETRE ARRAY

   Joe Lazio  

JPL

16 September 2011  

The Square Kilometre Array is intended to be the centimetre- and metre-wavelength telescope for the 21st Century. Originally proposed as the "hydrogen telescope," the science case is now recognized to be much broader, and the SKA will address fundamental questions in astrophysics, physics, and astrobiology.
The international science community has developed a set of Key Science Programs: (1) Emerging from the Dark Ages and the Epoch of Reionization; (2) Galaxy Evolution, Cosmology, and Dark Energy; (3) The Origin and Evolution of Cosmic Magnetism; (4) Strong Field Tests of Gravity Using Pulsars and Black Holes; and (5) The Cradle of Life & Astrobiology.
Dr Lazio will highlight how the SKA's Key Science Programs will be an integral component of the multi-wavelength, multi-messenger frontiers for astronomy and how the science pathfinding for the SKA is beginning now.

HIGH-SPEED OPTICAL QUANTUM MEMORIES

   Klaus Reim  

University of Oxford

10 June 2011  

In a globalised world with ever-increasing, intercontinental information exchange, there is growing demand for secure communication technology, such as could be provided by photonic quantum communications networks. Currently, the biggest challenge for such networks is distance. Over short distances, photons, interacting only weakly with their environment, easily and reliably carry quantum information without much decoherence, but intercontinental quantum communication will require quantum repeaters embedded in potentially isolated locations, because photon loss rises otherwise exponentially with distance. In general, these repeaters will require some sort of quantum memory, a coherent device where single photons are reversibly coupled into and out of an atomic system, to be stored, possibly processed and then redistributed. In order to be practically useful, this will need to have sufficiently large bandwidth, high efficiency and long storage time, with multimode capacity, and a low-enough noise level to enable operation at the quantum level.
Dr Reim will talk about an ensemble-based, far off-resonant Raman approach to quantum memories, describe how the interaction mechanism works and show how a single photon level signal may be stored in the quantum memory and retrieved at a controlled later point in time. Furthermore, he will address de-phasing mechanisms for the stored spin-wave excitation that limit storage times and discuss storage and retrieval of polarization-encoded qubits.

ION COULOMB CRYSTALS: CLASSICAL AND QUANTUM EFFECTS AT THE LINEAR-ZIGZAG TRANSITION

   Giovanna Morigi  

Universität des Saarlandes

27 May 2011  

A string of trapped, cold ions exhibits a structural phase transition to a zigzag structure, which can be tuned by adjusting the trap potentials and particle number. This proves to be a quantum phase transition, which can be mapped onto that of an Ising chain in a transverse field, and has a measurable deviation from the classical prediction. Three-dimensional Coulomb crystals of cold, trapped ions constitute a fascinating physical realization of the phenomena discussed by Wigner for electrons in metals, can be experimentally realized and probed, and have potential applications in quantum simulators and other quantum technologies.

AN ION TRAP IN A SILICON CHIP: A COMPONENT FOR ATOMIC QUANTUM TECHNOLOGIES

   Alastair Sinclair  

National Physical Laboratory

20 May 2011  

Scalability of atomic systems for quantum technologies is a significant challenge. To address this, microfabrication techniques are increasingly used to realise chip-based architectures for confining atomic particles.
The NPL team has developed a microfabricated ion trap chip using scalable processing techniques, based on gold-coated, oxidised silicon. This trap possesses a unique set of credentials and is now operational. Confined in the deep potential afforded by the 3D monolithic structure, ions exhibit motional frequencies of a few MHz and a low heating rate. While first devices consist of only a few trapping segments, the fabrication process will enable devices containing a complex array of many electrodes.
This talk will describe the fabrication and elementary operation characteristics of the chip-scale ion trap. Applications prospects for the device, which include quantum metrology & sensors, and quantum processors & networks, will be discussed.

NEW ADVENTURES IN ULTRAFAST AND SINGLE MOLECULE OPTICS

   Philipp Kukura  

University of Oxford

13 May 2011  

Dr Kukura will discuss recent developments in the application of laser-based techniques to directly visualise and thereby study dynamic processes occurring on vastly different time and size scales in chemistry and biology. The first part of the talk will focus on combined experimental and theoretical efforts based on ultrafast spectroscopy aimed at revealing atomic motion on its intrinsic, femtosecond, time scale. Specifically, it will address the structural changes occurring during the primary step in vision, the 11-cis to trans isomerization of the retinal chromophore in the visual pigment rhodopsin, and its implications for rhodopsin reactivity and efficient photochemistry in general. The second part will introduce a novel microscopic imaging technique based on interferometric scattering (iSCAT) and illustrate its use for high-speed, three-dimensional nanometric tracking of nanometer-sized objects. Particular attention will be geared towards recent results on the nanoscopic motion of individual virions diffusing on artificial membranes as well as the extension of iSCAT towards label-free sensing and the first detection and imaging of single molecules in absorption.

THE MOLECULAR MECHANISM OF RESPIRATION

   Philippa Roberts  

University of Cambridge

6 May 2011  

Synthesis of the biological molecular 'energy carrier' ATP is driven by a mitochondrial electrochemical gradient, in which the transfer of electrons between donors and accepters is coupled to the transfer of H+ ions (protons). The biological catalytic cycles are fairly well understood, in so much as we know which chemicals react with which enzymes, but the molecular mechanism of electron transfer and proton translocation remains something of a puzzle.
Some of the mechanisms most likely involve coherent quantum hopping of electrons through a chain of iron-sulphur clusters and a conformational change that drives proton transport across the mitochondrial inner membrane. This talk discusses recent advances towards understanding the proton translocation mechanism and electron transport mechanism within the enzyme.

STRONGLY INTERACTING PHOTONS

   Charles Adams  

University of Durham

1 April 2011  

The control of light at the few photon level is compromised by the absence of sufficiently large optical non-linearities. To overcome this limitation, photons may be mapped into atomic Rydberg excitations that have extremely large dipole-dipole interactions. The interaction between Rydberg atoms creates a photon blockade, leading to a large non-linearity at the single photon level.

THE HUNDRED YEAR HUNT FOR THE RED SPRITE

   Peter McLeish  

25 March 2011  

This presentation documents one of the most unexpected atmospheric scientific findings of the late 20th century. For over a century, people – including well-respected scientists – had reported seeing strange lights in the night sky about thunderstorms. But it remained until a "happy accident" in 1989 for the first such event to be captured on video tape with a low-light camera. One researcher exclaimed it was as if Biology had just suddenly discovered a new human body part. Since then, an entire "zoo" of luminous creatures has been found in the thin air above thunderstorms – and discoveries are still being made. The presentation also examines how the public can become engaged in the search for new thunderstorm-related electrical phenomena.

OPTICAL NANOFIBRES FOR PROBING AND MANIPULATING PARTICLES

   Sile Nic Chormaic  

University College, Cork

18 March 2011  

Dr Nic Chormaic will discuss tapered optical fibres of subwavelength diameter, including their fabrication and use in a range of experiments, and will explore how dark nanofibres can be used to probe the characteristics of laser-cooled atoms and how bright nanofibres are used to study surface interaction effects between the atoms and the fibre surface. Finally, she will consider higher order mode propagation within an optical fibre and discuss how this could be used to generate ordered arrays of trapping sites around the fibre for cold atoms or colloidal particles.

THE SIZE OF THE PROTON

   Randolf Pohl  

Max Planck Institute for Quantum Optics

11 March 2011  

The proton charge radius R_p has recently been determined by means of laser spectroscopy of the exotic "muonic hydrogen" atom with ten times higher accuracy than the present CODATA value of R_p - but 5 sigma away from it. It is not yet clear how this discrepancy has to be interpreted. Ultimately, the result could question the validity of the most precisely tested fundamental theory of matter and light, or change the value of the most precisely determined fundamental physical constant.
The muon, which is the 200 times heavier cousin of the electron, orbits the proton with a 200 times smaller Bohr radius compared to regular hydrogen. This enhances the sensitivity to the proton's finite size tremendously.

ANOTHER PHYSICIST IN FINANCE

   Dean Read  

IMC Financial Markets, Amsterdam

25 February 2011  

For a couple of decades there has been a flow of doctorate level physicists to the financial services industry. This talk aims to provide some insight into what these so called ‘Rocket Scientists’ are doing and why their physics background is even relevant in an arena where the only goal is to buy low and sell high.

THE PHYSICS OF SNOW

   Paul Connolly  

University of Manchester

18 February 2011  

Snowflakes form when vapour grown ice crystals aggregate together. The rate at which this happens can affect whether snow reaches the ground or not. This talk will cover the physics of snow formation and will present laboratory data of snow formation in the Manchester Ice Cloud Chamber to test our understanding of the efficiency by which ice crystals stick together.

VARIATIONS ON A THEME OF AHARONOV AND BOHM

   Michael Berry  

University of Bristol

11 February 2011  

The partial anticipation of the Aharonov-Bohm (AB) effect by Ehrenberg and Siday was an approximation whose wavefunction was not singlevalued; its connection with the singlevalued AB wave involves a ‘many-whirls representation’ in terms of waves winding round the flux line. AB is a fine illustration of idealization in physics. There are four AB effects, depending on whether the waves and the flux are classical or quantum; in the classical-classical case, fine details of the AB wavefunction have been explored experimentally in ripples scattered by a water vortex. The AB wave possesses a phase singularity, and there is a similar phenomenon in general interferometers. There are connections between the AB wave and the Cornu spiral describing edge diffraction. In bound systems, the half-flux case exhibits unexpected energy-level degeneracy structure.

ATOMIC COOPERATIVITIY IN CAVITY QUANTUM ELECTRODYNAMICS

   Jon Goldwin  

University of Birmingham

4 February 2011  

Optical cavities can provide a way to enhance the basic interactions between light and matter. Dr Goldwin will discuss experiments where microfabricated Fabry-Perot resonators are used to detect clouds of cold atoms at densities below one atom per cavity mode volume. It is observed that the signal fluctuations due to random atom numbers and positions are heavily suppressed, leaving photon counts near the shot noise limit. This noise reduction may be traced back to the nonlinear interaction of the collective atomic dipole with the quantum optical field of the cavity.

GYROCOPTERS

   Steve Boxall  

The Gyrocopter Experience

28 January 2011  

Invented by Spanish engineer Juan de la Cierva and first flown in 1923, the gyrocopter or autogiro is best known to most from the 1967 Bond film You Only Live Twice. Unlike the helicopter which uses its engine to power the lift-generating rotor directly, the gyrocopter has a freely-rotating rotor whose blades act like the wings of a glider, the aircraft being maintained in flight by the horizontal thrust from a conventional propeller. The result is a simple aircraft with much of the manoeuvrability of a helicopter, which requires a (short) ground run to become airborne but can achieve a near-vertical descent to land.
Recent refinements to classical designs have brought a new generation of commercially-produced two-seat aircraft that have propelled the gyrocopter from the domain of the quirky enthusiast to the mainstream, and gyrocopter schools are opening across the country. Steve Boxall - a gyrocopter pilot for over a decade and flight instructor for over 20 years - is the chief instructor of the Gyrocopter Experience at Old Sarum; in this talk, he will describe both the principles and joys of gyrocopter flight.

ACCELERATORS - GIANT OR COMPACT - FOR SCIENCE, INDUSTRY AND SOCIETY

   Andrei Seryi  

John Adams Institute for Accelerator Science

21 January 2011  

Accelerator science is a key element for discoveries in high energy physics, and is a crucial source for many advances in biology, medicine, solid state physics, future energy production, and various other fields. The size of facilities spans from international mega projects to university-scale installations. Interdisciplinary research on the boundaries of accelerator, laser, and plasma physics will revolutionize the entire landscape of accelerator science and open possibilities for stronger connections to industries. The modern trends in accelerators and compact X-ray and THz sources will be discussed in the context of future plans of the John Adams Institute for Accelerator Science, as well as within the national and international context.

EXPLORING STRONGLY CORRELATED QUANTUM MATTER IN ARTIFICIAL CRYSTALS OF LIGHT

   Immanuel Bloch  

Max Planck Institute for Quantum Optics and Ludwig Maximilians University, Munich

3 December 2010   

The realization of ultracold quantum gases at Nanokelvin temperatures has marked a milestone in modern quantum physics. With the help of laser light, these ultracold atom clouds can be stored in artificial periodic potentials created by laser light - so called optical lattices - that allow us to explore fundamental aspects of strongly interacting fermionic and bosonic quantum matter. In very recent experiments, the Munich groups have been able to record single snapshots of a quantum fluid in which individual atoms are detected with single lattice site resolution. This opens unprecedented novel opportunities for analyzing and manipulating strongly interacting quantum system. In his talk, Prof Bloch will review some of the recent experiments on strongly correlated quantum gases in optical lattices and highlight connections to condensed matter physics, quantum information science and atomic- and molecular physics.

FOCUSING AND IMAGING IN DISORDERED SYSTEMS:
WHY YOU CAN SEE MORE SHARPLY THROUGH A DIRTY WINDOW

   Allard Mosk  

University of Twente

26 November 2010   

In opaque white materials such as paper, paint and biological tissue, light is randomly scattered and loses its direction completely as it diffuses through the system. Dr Mosk's group has shown experimentally that light can be controlled as it propagates within and through such disordered materials. Remarkably, the scattering can even improve control. Phase coherence, and therefore the possibility for the light to show interference phenomena, is not lost by elastic scattering processes. By manipulating the incident wavefront, it is possible to force constructive interference at any point in space and thereby focus light inside and through opaque materials. Wavefront shaping can also drastically change the total transmission through a material, displaying a universal mode of wave transport. Dr Mosk will discuss eigenchannels of the transmission matrix, special wavefronts in which the energy is fully transmitted or fully reflected by a random scattering material. Since the first introduction of wavefront shaping methods in optics of random scattering materials, several exciting new developments have brought the method much closer to practical applications in technology and medicine.

HOW ANIMALS NAVIGATE

   D F H 'Pinky' Grocott  

Royal Institute of Navigation

19 November 2010   

The Monarch butterfly migrates 2,000 to 3,000 km using primarily a sun compass and magnetism, while turtles find the way back to their place of birth after 20 years. These are just two of the extraordinary examples that Air Cdre 'Pinky' Grocott will be using to illustrate the many different techniques that animals use to find their way around - from polarized light and magneto-reception to smell. A past President of the Royal Institute of Navigation (RIN), Air Cdre Grocott has many years experience in both air and animal navigation.

THE GEONIUM CHIP: A SUPERCONDUCTING PLANAR PENNING TRAP FOR ELECTRONS

   José Verdú-Galiana  

University of Sussex

12 November 2010   

Penning ion traps are used in a wide variety of applications, including mass spectrometry, high precision measurements of atomic and nuclear properties and the production of antihydrogen. Originally motivated by recent proposals for the implementation of a quantum processor with trapped electrons, novel, scalable, planar Penning traps have been designed and fabricated, but the observation of a single trapped electron remains an open challenge. The Sussex group has conceived a planar Penning trap technology which allows the capture and efficient detection of a single electron in a design inspired by extraordinary developments in planar microwave technology. Superconducting microwave resonators have been fabricated, and are capable of storing a single photon for a long time, thus permitting the coherent transfer of quantum information between different physical systems within the chip. This has led to a new theoretical approach, known as circuit-quantum electrodynamics (circuit-QED), to describe the interactions of (artificial) atoms and photons using concepts and methods of circuit theory. Dr Verdu-Galiana will describe the novel superconducting Coplanar Waveguide-Cavity Penning Trap and his recently started project to develop a geonium chip where, among other applications, a single trapped electron will become one of the basic building blocks of future quantum circuits.

EXTRACTING STRUCTURE FROM SIGNALS

   Nick Jones  

University of Oxford

5 November 2010   

Scientific optimism suggests that the data we collect has an underlying simplicity. Yet experience tells us that detecting this simple structure can be hard. How to select the best method for probing signal structure from a zoo of tools for time series analysis is often very unclear. Dr Jones will discuss a recent, extensive, synthesis of methods for data analysis; this yields a powerful tool for probing not only the empirical structure of signals but also their methods and models. He will then consider how this helps characterize nanopores, epilepsy, bird-song, fractional brownian motion, and detrended fluctuation analysis.

LIGHT TO COOL, MANIPULATE AND PROBE MANY-BODY SYSTEMS WITH ULTRACOLD BOSONS

   Chiara Fort  

LENS and Università di Firenze

29 October 2010   

This talk will describe how laser light is used in current experiments to simulate and study many-body physics using ultracold quantum gases. In particular, after a general introduction, Dr Fort will report on recent experiments performed at LENS where inelastic light scattering is used to probe correlated phases produced by loading a Bose-Einstein condensate into optical lattices.

A FLUID MOTION APPROACH TO COSMOLOGY

   Geoffrey Lilley  

University of Southampton

22 October 2010   

Prior to the explosion of research during the past century on Cosmology, following Einstein's work on Relativity, the fields of Fluid Mechanics and Optics, leading respectively to the propagation of sound and light, were regarded as having much in common since they were governed by the same unique wave equation, even though sound waves were longitudinal and light waves were transverse and travelled a million times faster than sound. It was common to study phenomena such as wave interference using the shallow water ripple analogy tank since shallow water surface waves, sound and light all obeyed the same wave equation, and hence had similar solutions for the same ratio of source speed to wave propagation speed in the appropriate medium: respectively water, air and the ether.
The ether had been introduced as long ago as the Greeks and more recently by Huygens and even Newton to support wave motion in the universe. Its properties were unknown and were stated by Maxwell, in introducing the equations of electromagnetic radiation, as the greatest unknown property of all science. All experiments failed in finding the ether and it was left to Einstein to introduce the postulate that since all attempts to find the ether had failed therefore for all practical purpose it could be assumed not to exist, and that all intergalactic space was a void. Thus at a stroke any connection between the propagation of sound and light was severed, and it was accepted that light could be propagated in a void whereas experiment confirmed that sound could not. The present work explores a possible model for dark matter as a physical realization of an ether of finite density, and its implications for a model of the Universe.

IN-SITU WAVEFRONT OPTIMIZATION:
    A NEW ROUTE TO IDEAL PERFORMANCE OF BIOPHOTONIC SYSTEMS

   Tomáš Čižmár  

University of St Andrews

15 October 2010   

State-of-the-art biophotonics laser systems frequently rely upon high numerical aperture objectives tightly focusing a laser beam, ideally into a diffraction limited spot, the smallest possible area where the total laser power can be concentrated. However, in all optical systems, optical and alignment imperfections result in deleterious aberrations that manifest themselves by an unwanted reduction of the focus intensity and a distribution of the optical power outside the focal volume. Such optical aberrations can be eliminated introducing an adaptive optical element but naturally, the wavefront distortion has to be recognized and properly quantified prior to the compensation being applied.
Dr Cizmar will present a method to eliminate all aberrations including those originating in the sample chamber and restore the optimal focusing of laser light in situ after propagating through a random scattering medium. It will be shown that the optimized spot can be used for optical trapping even for the case of a laser beam passing a very strongly scattering media present within the sample chamber. Other important applications will be demonstrated, including complex beam profiling, enhanced beam shaping, optical trapping with uncorrected optics, or controlling the laser output from a multimode optical fibre.

DETECTING PHASE TRANSITIONS IN SUPERCRITICAL MIXTURES:
    AN ENABLING TOOL FOR GREENER CHEMICAL REACTIONS

   Martyn Poliakoff  

University of Nottingham

8 October 2010   

Detecting phase transitions in high-pressure CO2 and supercritical fluids was first attempted in the nineteenth century. By contrast, Green Chemistry, the design and implementation of cleaner methods of manufacturing and processing chemicals, is barely 20 years old. Now, the use of CO2 as an environmentally more acceptable replacement for traditional solvents for greener chemical reactions is creating the need for new, more rapid methods for elucidating high-pressure phase behaviour. This lecture outlines some approaches, developed in Nottingham, to meet this need, including shear-mode quartz sensors, the fibre-optic reflectometer and pressure drop measurements.

CONTROLLING AND INTERFACING ATOMS AND LIGHT

   Axel Kuhn  

University of Oxford

18 June 2010   

In the endeavour of constructing a quantum computer, a major challenge is to couple and control a large ensemble of identical quantum systems at the single-particle level. In this colloquium, Prof Kuhn will first show how to interface single atoms with single photons in high-finesse optical resonators, and then introduce his group's approach of manipulating these atoms with an array of optical tweezers. These two approaches are the keys to scalable quantum networks, which one could use for quantum computing or simulation.

USING MATHEMATICAL MODELS TO PLAN FOR OUTBREAKS OF PLAGUE

   Ian Hall  

Health Protection Agency

11 June 2010   

The plague caused by the bacterium yersinia pestis is reckoned to have caused 200 million deaths since it was first recorded devastating the Byzantine empire in the sixth century, to have wiped out at least a quarter of the population of Europe as the Black Death in medieval times, and to have killed a fifth of London's population in the Great Plague of 1665-6. Spread then by fleas as an infection of the lymph nodes (buboes, hence bubonic), the plague can also infect the lungs and be spread directly from person to person through coughs and sneezes. Pneumonic plague is regarded as one of the most likely diseases to be used in a modern bioterrorism attack, and its epidemiology is therefore keenly studied.
Dr Hall will discuss the nature of this unpleasant and often fatal disease, how it is transmitted, its eco-epidemiology, and the crucial part played, when it occurs in modern society, by human perceptions and responses to it. He will outline some conclusions from epidemiological studies suggesting helpful strategies for managing any outbreaks, and will describe the role of the Health Protection Agency and other agencies in planning for and management of such events. The talk will be lavishly illustrated.
The Microbial Risk Assessment group, within the Health Protection Agency, is tasked with providing evidence based advice relating to new and emerging infections. Plague, in its various forms, is an endemic disease in parts of the world and is fatal in almost all untreated cases. As such it is a risk to public health and this presentation considers the effect of natural disease importation on wildlife ecology, the impact of small numbers of human cases of pneumonic plague and the control of larger releases. Whilst evaluating the control of larger releases we analyse the results from a behavioural survey on public reaction to plague releases. The evidence base for assumptions and parameterisation of models when used to inform contingency plans must be critically appraised.

SIXTY YEARS ON ICE

   Charles Swithinbank  

British Antarctic Survey & Scott Polar Research Institute

28 May 2010   

Charles Swithinbank is the first person to have an unbroken career in polar research from graduation to retirement. His first Antarctic expedition at the age of 22 led to an Oxford D.Phil in glaciology. He went on to work in Arctic Canada before enjoying 26 years with the Scott Polar Research Institute, the British Antarctic Survey, the U.S Antarctic Program and the Soviet Antarctic Expedition. He has voyaged to the North Pole in a submarine and has worked at the South Pole.
Dr Swithinbank is the author of four volumes of autobiography.

QUANTUM GASES - QUANTUM SIMULATION AND PRECISION SENSORS

   Kai Bongs  

University of Birmingham

21 May 2010   

Ultracold atomic gases offer a pristine resource for the study of fundamental quantum phenomena as well as the realization of ultraprecise sensors. The talk will present an introduction to cold atom physics and optical lattices. Here the bosonic superfluid to Mott insulator transition is one groundbreaking example of the possibility to simulate one quantum system with another one. On the applied side the talk will discuss quantum sensors based on atom interferometry and some technological developments in the area of quantum gases in space.

FIRST RESULTS FROM THE LHC

   Matt Coombes  

University of Southampton

14 May 2010   

With the Large Hadron Collider colliding particles at record energies since the end of 2009, there has been a great interest from the world's media and scientists. This talk aims to give a simple introduction to the exciting physics currently taking place at the LHC. Each of the four main experiments on the LHC ring will be introduced. The physics aims of each experiment will be discussed with a look at the new physics that may be observed at energy levels that only the LHC is capable of probing. A performance update of the LHC since its 2009 start up will also be given.

POLYMER SOLAR CELLS

   Neil Greenham  

University of Cambridge

7 May 2010   

Solar energy is ubiquitous, but for solar cells to contribute a significant reduction in carbon emissions they need to be cheaper than the current silicon technology and capable of being produced over vast areas. Solar cells based on semiconducting polymers are therefore attractive since they can be produced by roll-to-roll printing onto flexible substrates. The efficiencies of these cells are improving rapidly, but are still not high enough for large-scale application. Prof Greenham will describe some of the science surrounding organic solar cells, addressing the issues of how to separate charges in an organic semiconductor, how to reduce recombination losses, and how to image and control nanostructures on the nanometre lengthscales required.

INSECTS ON RUBBER AND DOGS ON SPRINGS: SENSING AND PERTURBING ANIMALS TO UNDERSTAND THE MECHANICS AND CONTROL OF LEGGED MOTION

   Andrew Spence  

Royal Veterinary College

30 April 2010   

One of the grand challenges in organismal biology is to understand how the nervous system produces locomotion. Animals move quickly through heterogeneous, three dimensional environments with stability and economy that far surpass our technology. This talk will present work that seeks to discover the control targets used by fast running, legged animals to achieve their remarkable performance. Results from insects and dogs running over soft surfaces will be presented, suggesting that many-legged runners use a different strategy than that of bipedal runners to compensate for soft surfaces. Yet the intriguing possibility exists in both systems that sinking into a surface may simplify the task for the neural controller, because of the mechanics of leg posture on foot touchdown. The implications of these results for the hypotheses of low-dimensional mechanical templates as targets of control, and of dimensional reduction in sensorimotor control, will be discussed. The integrative nature of this work, drawing on biology, physics, dynamical systems and control theory, as well as robotics, will be highlighted.

SYNTHESIS, EMERGENCE AND NEW PROPERTIES OF HYBRID NANOSCALE OBJECTS

   Steve Mann  

University of Bristol

23 April 2010   

Organized-matter chemistry is concerned with the synthesis, characterization and application of complex materials that exhibit order on length scales from the molecular to macroscopic. Recently, new strategies have been developed for the integration of organic self-organization and inorganic assembly such that hybrid nanoscale objects and nanostructures can be constructed by equilibrium (bottom-up templating) or non-equilibrium processes (synergistic emergence). These principles will be illustrated using several examples of the Bristol group's most recent work including the co-assembly of block copolymer/titania (silica) nanowires, synthesis of metallic nanowires arrays within cross-linked protein crystals, reconstitutive co-assembly of graphene/DNA nano-hybrids and the unprecedented formation of solventless liquid proteins at room temperature.

SUSTAINABLE ENERGY - THE IMechE UK ENERGY PLAN FOR 2050

   Alison Cooke  

University of Cambridge & Cooke Associates

19 March 2010   

How easy is it to get off our fossil fuel habit? Could Britain live on its own renewable energy? How does our current energy consumption compare with our sustainable energy options? Dr Alison Cooke will offer a straight-talking assessment of the engineering challenges involved, and discuss how to make energy plans that add up, based on the IMechE UK Energy Plan which was presented in Copenhagen in September 2009 alongside 9 other countries.
Dr Cooke is a Fellow of The Institution of Mechanical Engineers and Chair of the UK's Future Climate Steering Group, an international project to mobilise engineers from over 10 developed and developing countries.

ENERGY CONCENTRATION IN COMPOSITE QUANTUM SYSTEMS

   Almut Beige  

University of Leeds

12 March 2010   

The spontaneous emission of photons from optical cavities and from trapped atoms has been studied extensively in the framework of quantum optics. Theoretical predictions based on the rotating wave approximation (RWA) are in general in very good agreement with experimental findings. However, current experiments aim at combining better and better cavities with large numbers of tightly confined atoms. Here we predict an energy concentrating mechanism in the behavior of such a composite quantum system which cannot be described by the RWA. Its result is the continuous leakage of photons through the cavity mirrors, even in the absence of external driving. We conclude with a discussion of the predicted phenomenon in the context of thermodynamics.

LASER-DRIVEN PLASMA ACCELERATORS

   Simon Hooker  

University of Oxford

5 March 2010   

Electrons are pushed away from the front and back of a high-intensity laser pulse as it propagates through a plasma, leading to the formation of a plasma wave which trails the laser pulse. The longitudinal electric field within this wave can be as high as 100 GV/m – more than three orders of magnitude larger than that found in the RF accelerators used at synchrotron and particle accelerator facilities around the world. Laser-driven plasma accelerators are therefore able to accelerate particles to high energies in a fraction of the length required with conventional technology, and in the longer term may offer a way to reach energies beyond those possible with current technology.
Prof Hooker will describe the operation of laser-driven plasma accelerators and discuss the factors which limit the beam energy that they can reach. He will present the results of several experiments, including recent experiments with the Astra-Gemini laser, in which electron beams were generated with energies up to 1 GeV. He will also discuss the application of laser-driven plasma accelerators to the generation of tunable femtosecond-duration x-ray pulses, as well as their potential for reaching energies significantly beyond the GeV range.

GOLD NANOPARTICLES, PEPTIDES AND CELLS: THE DYNAMIC PICTURE

   Raphael Levy  

University of Liverpool

26 February 2010   

The dynamic interactions and fate of nanomaterials in contact with living systems is thought to be controlled by the structure and chemical properties of its interface. In most cases, the interface is formed by a layer of organic molecules (polymers, proteins or small molecules). This layer is itself dynamic and can evolve due to ligand exchange, enzyme activity and non-specific binding. The layer encodes the specific recognition properties of the particle and also often carries active moieties. It is therefore critical for the progress of the field that the chemical integrity of the layer and the fate of the core materials can be followed independently in real time.
Using a combination of photothermal (imaging of the core material) and fluorescence (imaging of the organic layer) the Liverpool group has shown that peptides and proteins attached to nanoparticles are degraded by the enzyme Cathepsin L upon cell entry. This process is generic: Cathepsin L is ubiquitous and is able to cut a third of the proteome. Such potential degradation has to be taken into account in the design of future bioconjugated nanomaterials.
The degradation mentioned above occurs in the endosomal/lysosomal compartments of the cell. Finding intracellular delivery strategies which reach the cytosol and bypass these compartments is of primary importance for applications of nanomaterials in imaging and nanomedicine. Dr Levy will present a range of approaches currently under investigation in our lab, including the use of targeting peptides and permeabilizing toxins.
Another major challenge in the field is the structural characterization of nanomaterials. This challenge is similar to the one faced by biologists in the early days of structural biology. Dr Levy will report on recent progress on the structural characterization of peptide-capped nanoparticles.

QUANTUM-OPTO-MECHANICS: QUANTUM-OPTICAL CONTROL OF NANO- AND MICRO-MECHANICAL SYSTEMS

   Markus Aspelmeyer  

University of Vienna

19 February 2010   

Nano- and micromechanical resonators are about to become a new paradigm system for quantum science. They combine features that allow unique approaches in both quantum foundations and quantum applications. For example, their flexibility to couple to a variety of physical systems (photons, electrons, atoms etc.) together with their on-chip integrability promises novel transducer schemes for quantum information processing. At the same time, their mass and size allows access to a hitherto untested parameter regime of macroscopic quantum physics such as quantum superposition states involving objects that are visible to the bare eye.
Quantum optics provides a well-developed toolbox to enter and control the quantum regime of mechanical systems. Prof Aspelmeyer will briefly highlight the recent developments of the field and report the current status in his Vienna experiments on laser cooling micromechanical resonators towards their quantum ground state and on strong optomechanical coupling to achieve coherent quantum control. He will also discuss recent progress towards generating optomechanical quantum entanglement, which is at the heart of Schrödinger’s cat paradox.

CLIMATE CHANGE AND SUSTAINABLE ENERGY

   Hugh Hunt  

University of Cambridge

5 February 2010   

Is climate change for real? If so, what can we do about it? What is my own carbon footprint? What can I do make a difference? These are the sorts of questions that are addressed in this talk. To answer them we need to do "sums" - just simple addition and multiplication is enough. We must reject solutions that don't "add up" and we mustn't rule out possible solutions purely on emotive grounds. Most people take sides before they've looked at the sums. Our future is in the balance and we're in danger of making the wrong choices.
This talk will draw on material from David MacKay's excellent book "Sustainable energy without the hot air".

RYDBERG AGGREGATES: INTERACTIONS IN AN ULTRACOLD GAS OF RYDBERG ATOMS

   Matthias Weidemüller  

University of Heidelberg

29 January 2010   

Due to the long-range character of the interaction between highly excited atoms, the dynamics of an ultracold gas of Rydberg atoms is entirely determined by van-der-Waals and dipole-dipole interactions. One outstanding property is the tunability of the strength and the character of the interactions with static electric fields. This allows one to explore the transition from a weakly coupled two-body system to a strongly coupled many-body system. The long-range interaction leads to many-body entanglement and has possible applications in quantum computing. In this talk, Prof Weidemüller will first give a general introduction into the field of Rydberg gases with special emphasis on our recent experiments.
In recent experiments, the Heidelberg group has studied coherent phenomena in an ultracold gas of Rydberg atoms under the influence of dipolar interactions. The Rydberg gas is formed in in a magneto-optical trap via cw two-photon excitation of Rb atoms into states with principal quantum number 30 to 100 using cw lasers at 780 nm and 480 nm. Recent results include coherent Rabi oscillations between ground and Rydberg states and the observation of the dipole blockade in a mesoscopic sample, stimulated rapid adiabatic passage with 90% transfer efficiency into Rydberg states, and studies of the many-body character of resonant energy transfer processes. These experiments reveal the role of interaction-induced mechanical forces as well as the influence of black-body radiation on the many-particle motional dynamics of the system. The latest experiments have revealed the antiblockade of excitation, as the antipode of the dipole blockade, and have explored coherent population trapping under the influence of long-range van-der-Waals forces.

THE SILENT FLIGHT OF THE OWL (AND APPLICATIONS TO THE DESIGN OF FUTURE QUIET COMMERCIAL AIRCRAFT)

   Geoffrey Lilley  

University of Southampton

22 January 2010   

The Owl is the only vehicle that flies silently. It is thought from the fossil record that the owl achieved this some 20 million years ago, and accounts for its survival In this talk we will discuss the details of the owl's hushkit which involves both the aerodynamics and the aeroacoustics as well as the flight performance of the owl. The differences of the owl's feathers from most other birds have been studied by ornithologists for many years but it is only relatively recently that we have measurements and thus discovered a physical understanding of the mechanism involved in achieving silent flight. We conclude the lecture by exploring how we might use Owl Technolgy in the design of future Quiet Commercial Aircraft to almost reduce noise to the ambient level on the take-off and approach to landing when flying over residential areas near airports.

COCHLEAR IMPLANTS: SIGNAL ENGINEERING FOR PROFOUND DEAFNESS

   Carl Verschuur  

University of Southampton

8 January 2010   

Cochlear implants are surgically implanted devices that provide a sensation of hearing, along with some ability to perceive speech, to individuals with severe to profound deafness who cannot benefit from acoustic hearing aids. This talk will provide an overview of what cochlear implants are, how they work, what benefits they provide for recipients, and what technical and scientific challenges lie ahead in the treatment of profound deafness with implantable devices.

LUCID: PUTTING A CERN DETECTOR IN SPACE AND IN SCHOOLS

   Becky Parker MBE  

Langton Star Centre, and
Simon Langton Grammar School for Boys

11 December 2009   

The Langton Star Centre at Simon Langton Grammar School for Boys is working closely with CERN and Surrey Satellite Technology Limited to put a new design of cosmic ray detector into space. This will be linked to an array of school detectors with the aim of giving students the opportunity to be involved in real physics research when they are at school. The wealth of data expected will make use of the facilities of the GridPP. We are hoping that working in this way with CERN technology will enthuse students and encourage them to consider taking physics and engineering further.

THE ELECTRON'S ELECTRIC DIPOLE MOMENT

   Jony Hudson  

Imperial College, London

4 December 2009   

Some theories beyond the standard model predict that, when examined with sufficiently high resolution, the electron will no longer appear to be point-like and may instead show some finite structure. This should be apparent as an electric dipole moment parallel to the electron's spin. Because spin is inverted if time is reversed, the existence of an electric dipole moment would violate time-reversal and parity symmetries: central assumptions of the standard model.
Any electron electric dipole moment will be manifest as small shifts in atomic spectra, and such effects have long been predicted to be greatly enhanced when the atoms are within polar molecules. The Imperial College group has therefore been running a long campaign to measure, with ever increasing precision, the electron's electric dipole moment in the spectra of ytterbium fluoride. Based upon matter-wave interferometry for the highest resolution, these elegant experiments also provide a fascinating example of the challenges of eliminating systematic errors in the measurement of fundamental physical properties.

CURRENT AND FUTURE POWER GENERATION

   Jonathan May  

e.on UK

27 November 2009   

The critical questions of how, where and from what we generate power, and how it is distributed, depend upon environmental sustainability, geopolitics, technological developments, and the availability and geographical distribution of energy sources. Our current pattern of coal, gas, nuclear, hydroelectric and wind-based power stations will have to change substantially if we are to meet future demand in a safe, secure and sustainable fashion.
This talk will describe some of the methods by which we generate and distribute power at present, and their suitability for meeting future needs. It will then examine a range of technologies for future power generation, and some of the challenges that they present.

CREATING AND MANIPULATING COLD MOLECULES WITH INTENSE OPTICAL FIELDS

   Prof Peter Barker  

University College, London

20 November 2009   

The creation of cold molecular gases and the precise control of the centre-of-mass motion of molecules by external fields have become an important new field in molecular and ultra-cold physics and in chemistry. The long residence times of trapped cold molecular gases coupled, with their reduced momentum spread, allows high resolution spectroscopy and the study of molecular interactions that are normally masked by thermal averaging at temperatures above 1 K. An important example is cold, trapped dipolar gases, which offers a route to the study of many body condensed matter physics and quantum information processing in a well-controlled system that can be tailored using external fields.
In this talk, Prof Barker will review the development of techniques to slow and manipulate cold molecules focusing in particular on the optical Stark deceleration technique which uses the optical dipole force. He will then describe more recent work on how this force can be tailored using laser-induced alignment in strong optical fields. Finally, he will report on progress in his laboratory towards sympathetically cooling these molecules with ultra cold rare gas atoms with the aim of reaching the microKelvin temperature regime for a large range of molecular species.

MEDICAL IMAGING AND APPLICATIONS IN DRUG DISCOVERY

   Dr Will Hallett  

GSK Clinical Imaging Centre, Imperial College

13 November 2009   

Physics principles and techniques lie behind the many and astonishing methods of medical imaging, from nuclear magnetic resonance (MRI), positron emission (PET) and X-ray computed tomography (CT) to ultrasound, confocal microscopy and optical coherence tomography. Already indispensable in clinical use, these techniques are now also being applied to molecular imaging for drug discovery and development. Dr Hallett's talk will begin by outlining the basic physics of medical imaging techniques, before discussing some of their more important and intriguing applications.

SUPERPOSITION OF QUANTUM OPERATORS AND A TEST OF THE BOSONIC COMMUTATION RELATION

   Prof Myungshik Kim  

Queen's University, Belfast

6 November 2009   

One of the most striking formulas we learn during the undergraduate quantum mechanics course is the commutation relation, [a, a⁺] = 1. For a light field, this means that photon annihilation after creation is different from photon creation after annihilation and the difference is equal to the unity. The non-commutativity is closely related to the uncertainty principle in quantum mechanics; the precise measurement of two non-commutative observables simultaneously is impossible. Even though the bosonic commutation relation is taught in every quantum mechanics course, the direct and 'exact' proof seemed to be experimentally unreachable. In this talk, the verification of the bosonic commutation relation is discussed using single photon interference.
Prof Kim will demonstrate a scheme based on single-photon interference for transferring the microscopic quantum behaviour to macroscopic classical objects (as in Schrödinger's cat paradox) by realising arbitrary superpositions of distinct quantum operations. Applying them to a classical light field the commutation relation to be verified directly. The Belfast group's results may be interesting because, in addition to clear demonstration of the fundamental textbook concept in quantum mechanics, the possibility of implementing general operator superpositions is an alternative promising tool to control and engineer quantum information for future technologies.

ENGINEERING ATOM CHIPS

   Prof Michael Kraft  

University of Southampton

23 October 2009   

Atom Chips are a new and exciting technology that enable the manipulation of atoms close to a chip surface. These chips combine cold atom physics with MEMS microfabrication techniques to create electric, magnetic and optical fields to trap and manipulate ultra-cold atom clouds.
The microfabricated chips realise optical cavities, electrostatic actuators and current carrying wires to set up magnetic trapping fields. Besides fundamental physics experiments, there are a range of novel devices and sensors on the horizon that use this technology. In prototype devices, atom chips are already being used to make Bose Einstein condensates for applications including atomic clocks on a chip, atom interferometry, and quantum information processing.
The talk will describe micro-fabrication technologies that can realize the required building blocks and components to realize such atom chips. It will mainly focus on the microfabrication and design engineering aspects of these chips, as they almost entirely rely on non-standard fabrication techniques, which need to be specially developed for these chips. Additionally, they combine a range of different physical domains such as optical, magnetic and electrostatics, which makes their design and realization challenging.

THE HUNT FOR GRAVITATIONAL WAVES

   Dr Ed Daw  

University of Sheffield

16 October 2009   

The search for gravitational waves using ground based laser interferometers is now well underway, and becoming progressively more sensitive through an ongoing programme of instrument upgrades. In this talk, Dr Daw will discuss gravitational waves and the physical principles of interferometric detectors such as LIGO, Virgo and GEO600, before exploring the intriguing possibility of detection of a counterpart to a putative gravitational wave transient either in the optical or the radio. Such a dual-channel detection would provide compelling evidence for first direct detection of gravitational waves, as well as providing a wealth of information on the physics of compact gravitational wave sources.

LIGHT ON THE NANOSCALE: ENERGY HARVESTING AND THE OPTICAL ASSEMBLY OF PARTICLES

   Prof David Andrews  

University of East Anglia

9 October 2009   

Recent progress in the theory of photon interactions has revealed a catalogue of new mechanisms engaging the nanoscale propagation of light. At routinely achievable levels of laser intensity, non-resonant light can operate on pairs of particles can produce movements of energy and matter without itself suffering any change. Prof Andrews will begin by examining how non-resonant light can engage with, and modify van der Waals forces. The principles are readily understood from a quantum electrodynamical perspective, and a variety of applications is emerging. Some applications such as optical binding, already extensively demonstrated in experiment, offer a degree of control well beyond the capacity of simple optical tweezers. The phenomenon allows the ordering and patterning of particles in arrays and rings, and distinctive torques can be exerted. Other effects that originate from the same fundamental process extend from a novel optomechanical response (optical electrostriction) in transparent solids to an optical method of collapsing nanoparticle assemblies.
A further theme of the presentation is the more recent discovery of a means by which non-resonant laser light can promote, inhibit or switch the transfer of electronic energy between molecules. It transpires that precisely the same photonic coupling mechanism is again involved. Interest initially focused on laser-assisted modifications to the process of fluorescence resonance energy transfer (FRET); now attention is being given to switching applications. A variety of possibilities exist to effectively channel excitation between paired components; array implementations offer interesting opportunities for optical interconnect technology.

THE LONELY WORLD OF THE COLD, TRAPPED ION

   Prof Richard Thompson  

Imperial College, London

19 June 2009   

Single ions, trapped electrostatically in ultrahigh vacuum and slowed optically by exploiting the Doppler effect, can be held essentially stationary and isolated from the nearest matter many millimetres away. Narrow transitions in atomic ions are thus amongst the most ideal quantum systems that we know, and are therefore the favourite candidates for future frequency standards and metrology. When two such ions are held in the same trap, their interactions can be controlled with exquisite detail and precision, making them suitable for use as the processor of a quantum computer, with single ions providing the quantum memory.
Prof Thompson will describe recent work at Imperial with trapped and laser-cooled calcium ions. In one experiment the limitations to laser cooling have been overcome in the so-called Penning trap so that individual ions can be imaged and the configuration that two ions take in the trap can be manipulated. In another experiment small amounts of mixing between different levels of a configuration, induced by a magnetic field, have been demonstrated to lead to easily-observed effects in the fluorescence from a single ion. Prof Thompson will finish by discussing a proposal for the observation of a quantum phase transition in a string of trapped ions.

INTERFACING CELLS WITH COLLOIDAL NANOPARTICLES

   Prof Wolfgang Parak  

University of Marburg

12 June 2009   

Colloidal nanoparticles may be grown to have a variety of different functionalities, such as being fluorescent or magnetic. By using biological molecules to link them, particles of different functionalities can be integrated to form composite materials on the nm-scale. Applications of such particles in life science will be discussed.

DISCOVERIES THAT CHANGED THE WORLD: 1932-1942 - JAMES CHADWICK & LISE MEITNER

   Dr Gerry Lander  

Institute for Transuranium Elements, Karlsruhe & ILL, Grenoble

5 June 2009   

From the discovery of the neutron (1932) to the first demonstration of controlled fission (1942) was just ten years; a period that took physics from an occupation of a small number of eccentric gentlemen and (even fewer) ladies to something of concern to, and funding decisions of, Governments all over the world. The shadows of those tumultuous years are still with us, for better or worse.
This talk will recount those ten years through the lives of James Chadwick (1891-1974) and Lise Meitner (1878-1968), contemporaries who played pivotal roles in the events, even though, partly because of their retiring personalities, they are often overshadowed by "larger" figures.

COHERENT X-RAY IMAGING WITH X-RAY FREE ELECTRON LASERS

   Prof Henry Chapman  

DESY & University of Hamburg

29 May 2009   

The ultrafast pulses from future X-ray free-electron lasers may enable imaging of non-periodic objects at near-atomic resolution. These objects could include single macromolecules, protein complexes, or virus particles, and the method will be particularly valuable to determine the structures of proteins that cannot be crystallized. The specimen would be completely destroyed by the pulse, but that destruction will only happen after the termination of the pulse. To address the many challenges that we face in attempting molecular diffraction, Prof Chapman and his colleagues have been developing experimental methods at the FLASH free-electron laser at DESY in Hamburg: images have been reconstructed from single-pulse ultrafast diffraction patterns, and quantitative measurements have been performed of the explosion of test particles in the focused FEL pulse. No motion is observed during the pulse and the evolution of the explosion can be followed with a novel holographic time-resolved technique. These results confirm the basic principles of flash imaging and lend great confidence to achieving molecular imaging at future short-wavelength X-ray FELs.

RESTORATION OF FADED PHOTOGRAPHIC SLIDES

   Dr Geoff Daniell  

University of Southampton

22 May 2009   

One of Geoff's retirement projects has been the digitization of his old holiday slides, many of which have unfortunately deteriorated seriously with age. After an entire wet Sunday afternoon moving sliders on digital photo processing software, but discovering that he could not do better than the 'auto' button, Geoff decided that he ought to be able to improve upon the results by thinking about the physics of the photographic process. This talk will describe the mechanisms of old-fashioned photography, conjecture on why photographs have deteriorated, describe the algorithms he has developed, and show some results.

SUPER-HYDROPHOBIC SURFACES

   Dr Steven Bell  

Queen's University, Belfast

15 May 2009   

In the first decade following publication of Neinhuis and Barthlott’s studies of water repellent, self-cleaning plants there has been a huge expansion in research which attempts to mimic the exceptional properties of natural systems, such as the lotus plant. This talk will cover current progress in preparation of artificial superhydrophobic materials, including our work on electrolessly deposited metal coatings (see the metal pond skater with superhydrophobic legs shown here) and will include some practical demonstrations of the effect of adding superhydrophobic coatings to materials. It will also include some recent examples of superhydrophobic platforms for surface enhanced Raman spectroscopy and speculation on the potential applications for the technology.

GREEN AVIATION - FACT OR FICTION?

   Dr Kenji Takeda  

University of Southampton

24 April 2009   

Air travel is cited as being the fastest growing source of climate changing gases and heavily criticised for being a major culprit of global warming. This is despite air travel only contributing around 3% of global carbon dioxide emissions, and UK domestic air travel contributing less than 0.5% of UK carbon dioxide output. In this talk, Dr Takeda will explore the scientific, technical and social issues around air travel and climate change, and try to present a balanced view of where we are heading in the future. He will attempt to outline the steps required to ensure that aviation meets its environmental obligations to society in the 21st century.

GREENWICH MEAN TIME

   David Rooney  

Royal Observatory, Greenwich

20 March 2009   

Precise maritime navigation, in the days before radio, required precise timekeeping, and ships leaving the Port of London would set their clocks according to the timepieces and signals of the Greenwich Royal Observatory. Greenwich Mean Time - derived using precise chronometers from careful observations of solar transits - became a global maritime reference; when the railways required national coordination, it was adopted as the British civil standard, and in 1884 the Greenwich meridian officially became the international reference for navigation and timekeeping. Today's atom-based UTC is adjusted, by the addition or subtraction of leap seconds, to remain within a second of GMT. David Rooney - a physicist turned historian of technology - will outline the history of Greenwich Mean Time and some of its many quirky stories, including that of the Greenwich Time Lady whose family continued until 1940 to distribute the time to tradesmen by carrying a pocket watch around London.

LIQUID CRYSTALS FOR ELECTRO-OPTICS

   Dr Sally Day  

University College, London

13 March 2009   

Liquid crystals re-orient under the influence of a low voltage to give a very large change in the effective birefringence. Liquid Crystal Displays use this effect to change the polarisation of light, hence changing the intensity of transmitted light through polarisers. The change in birefringence can be used for other applications and this talk will describe some of these; from variable focal length lenses, tuneable Fabry-Perot filters, phase modulation for diffraction and applications in microwave devices. In addition, new displays, such as bistable displays and an autostereoscopic display will be discussed.

QUANTUM OPTICS WITH QUANTUM DOT SPINS

   Dr Mete Atatüre  

University of Cambridge

27 February 2009   

Self-assembled semiconductor quantum dots have atom-like properties such as discrete energy levels coupled by optical transitions, and their coherence properties can be revealed in quantum-optics experiments. Further, these transitions are governed by spin-dependent optical selection rules. This opens a channel to control and detect a single spin in a quantum dot via lasers. However, QDs can also interact strongly with a spin (nuclei) and/or a charge (electrons) reservoir of the solid-state environment leading to a rich source of interaction mechanisms. Consequently, identifying the regimes of these mechanisms is crucial for achieving a level of control in solid-state-based systems similar to that of atoms. Dr Atatüre will provide a highlight of recent progress on all-optical control of single and coupled quantum dot spins along with the current research directions in coherent light-matter interactions.

CONTROLLABLE SINGLE PHOTON SOURCES AND STRONG COUPLING

   Prof Robert Taylor  

University of Oxford

20 February 2009   

Much effort has been expended over the past few years in trying to develop controllable and triggerable single photon sources based on semiconductor emitters. Prof Taylor will discuss recent developments in the field and focus on what happens when quantum dots are coupled to external cavities to try and produce strong coupling in the solid state.

SYNTHESIS, PROPERTIES AND ASSEMBLY OF COMPLEX NANOCRYSTAL STRUCTURES

   Dr Liberato Manna  

University of Lecce

13 February 2009   

Current efforts and success of nanoscale science and technology are related to the fabrication of functional materials and devices in which the individual units and their spatial arrangement are engineered down to the nanometer level. One promising way of achieving this goal is by assembling of colloidal inorganic nanocrystals as the novel building blocks of matter. This trend has been stimulated by significant advancement in the wet-chemical syntheses of robust and easily processable nanocrystals in a wide range of sizes and shapes. The increase in the degree of structural complexity of solution-grown nanostructures appears to be one of the natural directions towards which nanoscience will increasingly orient. Recently, several groups have indeed devised innovative syntheses of nanocrystals through which they have been able to group inorganic materials with different properties in the same particle. These approaches are paving the way to the development of nanosized objects able to perform multiple technological tasks. This talk will review the recent advances in the synthesis of colloidal nanocrystals, with emphasis on the strategies developed at NNL for the fabrication of colloidal nano-heterostructures, as well as on their properties and their assembly.

QUASICRYSTALS: FROM FIBONACCI TO THE FRYING PAN

   Prof Ronan McGrath  

University of Liverpool

6 February 2009   

Do structural symmetry and periodicity matter when we try to understand the physical properties of ordered materials? Quasicrystals are intermetallic alloys which have long-range order without periodicity and hence display unusual rotational symmetries. Their structures are described by models related to Penrose tilings and Fibonacci numbers. This talk will introduce these materials and discuss using their surfaces as templates for building novel nanostructures and thin films. One of the main goals of the research programme is to clarify the physical consequences of classically forbidden structural symmetries and aperiodicity. Prof. McGrath will also mention potential applications arising from their unusual physical properties.

MOLECULAR PROPERTIES MEASURED BY NEAR-FIELD INTERFEROMETRY

   Dr Hendrik Ulbricht  

University of Southampton

30 January 2009   

Matter wave interferometry experiments with very massive molecules has the potential to test fundamental physics as the quantum to classical transition. But the very same experimental setup can also be used to investigate molecular properties as for instance static and dynamic polarizabilities, electric dipole moments, absoprtion cross sections and van der Waals interaction parameter from collision cross sections to an high degree of precision - as well as for molecular and nanoparticle beam sorting.
Dr Ulbricht will report on the recent status of molecule interfernce with Talbot-Lau and Kapitz-Dirac-Talbot-Lau interferometers with organic molecules of masses of up to 2500 amu and then extend on the various metrology opportunities. He will also discuss particle beam manipulation techniques for the slowing and cooling of massive molecules, which are central to both the probing of quantum limits and molecule metrology.

ON WANTING TO BE FREE: MUSIC MEETS TECHNOLOGY

   Paul Jessop  

RIAA

23 January 2009   

Music remains as popular as at any time in human history, but the way we get access to it and the way we consume it would be incomprehensible to our ancestors. Changes in music use have been enabled by some key technologies and the changes continue. This talk will review these technologies – such as audio compression, watermarking, fingerprinting and forensics. It will also look at some of the resulting issues in the music ecosystem where technology, policy, regulation, politics, creativity, ethics and consumer behaviour are sometimes pulling in orthogonal directions.

TAMING MOLECULAR BEAMS

   Prof Gerard Meijer  

Fritz-Haber Institute, MPI Berlin

16 January 2009   

Full control of both the internal and external degrees of freedom of molecules has been an important goal in molecular physics for many decades. Prof Meijer will describe the experimental approach developed by his group to produce samples of trapped neutral molecules. Based upon arrays of time-varying, inhomogeneous electric fields which reduce in a stepwise fashion the forward velocity of molecules in a beam, this so-called 'Stark decelerator' can transfer the high phase-space density present in the moving frame of a pulsed molecular beam to a reference frame at any desired velocity, with narrow velocity distributions that correspond to sub-mK longitudinal temperatures.
These decelerated beams offer new possibilities for collision studies, and enable spectroscopic studies with improved spectral resolution; first proof-of-principle experiments have been performed. They have also been used to load ND₃ molecules and OH radicals into an electrostatic trap at a density of 10⁷ mol cm^-3 and at temperatures of around 50 mK. Optical pumping of trapped neutral molecules due to blackbody radiation has been investigated, and trapping of molecules in vibrationally or electronically excited metastable states has been used to directly measure their radiative lifetimes. Ground-state molecules have been trapped in AC electric field traps, decelerated molecular beams have been injected in a prototype molecular synchrotron, and, using micro-structured electrode arrays, a "decelerator on a chip" has been constructed and tested.

RAINBOWS, CORONAS AND GLORIES

   Philip Laven  

9 January 2009   

Rainbows, coronas and glories are examples of atmospheric optical phenomena caused by the scattering of sunlight from spherical drops of water. Eminent scientists (such as Descartes, Newton, Young, Airy and others) offered various explanations for the formation of rainbows - and thus made major contributions to our understanding of the nature of light.
Given the availability since 1908 of Mie's rigorous solution for scattering of light by homogeneous spherical particles, it might be assumed that everything is now known about the rainbow, corona and glory. In fact, atmospheric optics has long been a neglected topic for scientific studies. It is only in recent years that rapid advances in computing power have allowed Mie's solution to be used to investigate these phenomena - and to produce full-colour simulations.
The physical processes resulting in the formation of rainbows and coronas are well understood, but most explanations of the glory involve lots of "scientific arm-waving". Using the results of detailed calculations and simulations, this talk will aim to provide some insight into the physics of rainbows, coronas and glories - and to encourage the audience to enjoy the beauty of these phenomena.

FORECASTING THE BRITISH WEATHER

   Kirsty McCabe  

Met. Office & BBC Weather Centre

12 December 2008   

While the weather provides the British with both a constant topic of discussion and a source of fascination, it presents the forecaster with endless challenges. The British Isles are influenced by polar and tropical air masses; they frequently find themselves beneath the jetstream, and are subject to untempered Atlantic weather about which we have only limited data. Few other locations see such notable changes in weather from place to place and day to day. It was to study and forecast this weather that a meteorological service was established by Admiral Fitzroy in 1854, and for 150 years the Met. Office has provided warnings of extreme weather to our mariners, armed services and general public.
Today's talk will give a behind the scenes look at weather forecasting, from understanding the atmosphere to numerical weather prediction, including an introduction to air masses, cloud formation and cloud classification, cases of wild weather - and the challenge of presenting the public forecast itself.

HYBRID INORGANIC/ORGANIC PHOTONICS

   Dr Stephanie Cheylan  

ICFO, Barcelona

5 December 2008   

Conjugated polymers have become attractive for a range of device applications such as light-emitting diodes, photo-voltaic cells and transistors. While there is true value in making all-plastic devices, some devices such as the diode laser still require an inorganic component to be feasible. In this talk, Dr Cheylan will outline some of the attractive properties of such hybrid devices.

EXPLORING EXTRASOLAR WORLDS: FROM GAS-GIANTS TO TERRESTRIAL PLANETS

   Dr Giovanna Tinetti  

University College, London

28 November 2008   

Since the presence of a planet orbiting the star Gamma Cephei was first established in the early 1990s, over 300 further extrasolar planets have been identified, using a wide range of observational techniques from astrometry and radial velocity measurement to gravitational microlensing and transit observations. The Hubble Space Telescope has allowed some remarkable advances, including the direct imaging this month of three planets around the star Fomalhaut in the constellation Piscis Austrinus. Spectroscopic measurements using the Hubble telescope have also allowed analysis of the atmospheres of these remote worlds, with the identification of water and methane around the hot, Jupiter-type planet HD 189733b, 63 light-years away in the constellation Vulpecula. Such measurements herald future analysis of cooler, more Earth-like and potentially habitable planets to reveal information about the atmospheric temperature, pressure, winds, clouds and chemistry of extrasolar planets where life could potentially exist.

ATOMIC FREQUENCY METROLOGY

   Dr Anne Curtis  

National Physical Laboratory

21 November 2008   

The precise measurement of time and frequency - the subject of the 2005 Nobel Prize in Physics - has major applications from fundamental science and the quest for physics beyond the standard model, to technologies such as ultra-precise satellite-based navigation. Dr Curtis will begin with a basic introduction to frequency metrology and an overview of the state-of-the-art in atom-based frequency metrology, including clocks based upon Cs fountains, single ions and neutral atom lattices. She will then discuss some fundamental physics experiments and more practical, real-world applications that depend upon such timepieces.

SPIN NOISE SPECTROSCOPY

   Prof Michael Oestreich  

Leibniz Universität, Hannover

14 November 2008   

Electron, hole, and nuclear spins in semiconductors offer additional degrees of freedom for a new kind of information processing and optoelectronic devices. In this talk, Prof Oestreich will first discuss the exciting prospects and challenges of semiconductor spintronics and afterwards describe how to extract the spin dynamics and spin relaxation in semiconductors solely by measuring noise. The experimental technique is called spin noise spectroscopy and allows non-demolition measurements of spin systems in thermal equilibrium with astonishing sensitivity.

ATTOSECOND ANGULAR STREAKING AND SUB-100AS TUNELLING TIME DYNAMICS

   Prof Ursula Keller  

ETH Zurich

7 November 2008   

Prof Keller's group has demonstrated attosecond angular streaking, a new technique to achieve attosecond time resolution using close to circularly polarized, intense pulses. The rotating electric field vector of the slightly elliptically polarized pulse is used to deflect photo-ionized electrons in the radial spatial direction, such that - like the minute hand of a clock - the instant of ionization is mapped to the final angle of the momentum vector in the polarization plane. Here, this ‘atto-clock’ makes one complete turn of the electric field each 2.4 fs. It requires pulse durations in the two optical cycle regime and carrier envelope offset phase (CEP) control, and can be used with or without any attosecond XUV pulses. The Zurich group has resolved subcycle dynamics in tunneling ionization by the streaking field alone, and demonstrated a temporal localization accuracy of 24 as rms and an estimated resolution of ?200 as.
The demonstrated accuracy raises the possibility of examining one of the fundamental aspects of quantum physics: the process by which an electron tunnels through an energetically forbidden region. Since the early days it has been debated whether tunnelling takes a real time or is instantaneous. Prof Keller will discuss the demonstration of intensity-independent “instantaneous” ionization with an upper limit of ?30 attoseconds over a Keldysh parameter variation of 1.45 to 1.17.

CODY AND ROE: TWO REMARKABLE MEN

   Mr Philip Jarrett  

Aeroplane Monthly

31 October 2008   

On 16th October 1908, 'Colonel' Samuel Franklin Cody made the first powered, sustained and controlled flight in Britain, just a few miles from here at the Army Balloon Factory in Farnborough. A few months later, just over the county border at the Brooklands motor-racing track in Surrey, Alliott Verdon Roe was testing his first full-size aircraft which, after tentative hops in July 1908, first flew properly the following year. Cody’s exploits led to the establishment of Farnborough as Britain’s leading centre for aircraft research and development, while Roe went on to found the world-famous AVRO aircraft manufacturing company, and subsequently Saunders-Roe Aviation on the Isle of Wight.
The two men were very different characters - Cody a flamboyant extrovert, Roe much more reserved. But both were remarkable individuals and equally great pioneers of British aviation. This lecture will highlight their achievements, describe their respective approaches to the problems of powered flight and discuss how they went on to develop and fly progressively improved versions of theiraeroplanes over the following few years.

A RANDOM WALK APPROACH TO QUANTUM COMPUTING

   Dr Viv Kendon  

University of Leeds

24 October 2008   

In a quantum world - the regime in which quantum effects are not disguised by thermal motion and dissipation - common, classical phenomena can assume rather different characteristics. Beginning with a gentle introduction to quantum computing, Dr Kendon will explain the mechanisms and characteristics of the quantum versions of random walks. Intriguingly, quantum walks can actually be improved in some cases by adding a little noise instead of striving to keep them perfect.

CLOSING IN ON ULTRA-HIGH ENERGY NEUTRINOS

   Dr Amy Connolly  

University College, London

17 October 2008   

Dr Connolly will describe current and future experiments that seek ultra-high energy cosmic neutrinos, which are so evasive they require detection volumes beyond 100's of km³. Volumes of such size are achievable using the radio Cerenkov technique, and Dr Connolly will discuss current and future projects that use this detection method, including the ANITA balloon experiment which just completed its first physics flight in the 2006-2007 Austral summer and whose second flight is scheduled for December this year.

POLARISED FERMI GASES

   Dr Carlos Lobo  

Universities of Cambridge & Southampton

10 October 2008   

In the past two years various experiments have been carried out at Rice University and MIT on ultracold gases of fermionic atoms where one type of spin component is more abundant than another. These so-called polarised or imbalanced gas experiments may soon answer tantalising questions regarding Fermi superfludity which have been around for over 45 years. Dr Lobo will review the experimental situation and describe how some of the puzzling data can be understood in terms of normal state properties of these strongly interacting systems.

STRING THEORY FOR HERETICS

   Prof Nick Evans  

University of Southampton

20 June 2008   

(Nick has sadly been too busy to provide an abstract for his talk this Friday, but I think I can remember the gist...)
String - as Raymond Baxter explained so memorably in his classic 1976 Goodies cameo - has a thousand uses: from cartlidge replacements in hospital operations, to a substitute for conventional electric wiring - "safer and cheaper because... it doesn't work". Yet while Baxter was astonished that a mere television studio could be built from string, modern theories suggest that it may hold together the entire universe.
'Most physicists nowadays,' according to a more recent science programme, 'believe in string theory'. Nick's talk is aimed at the rest of us, who have barely a clue what it's all about.

RADIO TELESCOPES AS PHYSICS FACILITIES

   Prof Steve Rawlings  

University of Oxford

13 June 2008   

Traditionally radio telescopes have been used by astronomers. The next generation of telescopes will have such new capabilities that they will be capable of performing experiments that impact on issues of fundamental physics: the testing of General Relativity in the strong-field limit; the measurement of neutrino masses; the nature of dark energy etc. Prof Rawlings will review prospects for the future, and specifically the scientific pathway to the Square Kilometre Array (SKA).

THE ANTIKYTHERA MECHANISM

   Prof Mike Edmunds  

University of Cardiff

30 May 2008   

Over a century ago, sponge divers near the island of Antikythera discovered an ancient device that astonished experts worldwide. Now known to date from the first century B.C., and considered the most sophisticated known mechanism from the ancient world, this fascinating bronze and wooden relic has only recently begun to divulge its intriguing secrets. X-ray and novel computer-aided imaging techniques have allowed an international team of researchers from mathematicians and physicists to astronomers and palaeographers to identify the Antikythera Mechanism as a complex mechanical 'computer', dedicated to astronomical phenomena, to track the cycles of the Solar System. No other mechanism as complex is known until a thousand years later.

THE PHYSICS OF WOODWIND INSTRUMENTS

   Dr David Sharp  

Open University

23 May 2008   

The woodwind family of musical instruments includes, amongst others, the flute, oboe, clarinet, bassoon and saxophone. Through a series of demonstrations and multimedia examples, this talk discusses the physics of the woodwind instruments. In particular, the mechanisms by which the different instruments produce sound are described and the reasons why each woodwind instrument has its own characteristic tone are explained.

NANOPHOTONICS AND BIOCHEMISTRY

   Prof Jochen Feldmann  

Ludwig-Maximilians-Universität, Munich

16 May 2008   

Nanoplasmonics offers new tools to analyze or to manipulate biomolecules, whereas the self-recognition capabilities of biomolecules help to assemble hybrid nano-assemblies with unique optical properties and functions. Prof Feldmann will show several examples of how these two fields profit from each other.

ATTOSECOND DYNAMIC IMAGING

   Dr John Tisch  

Imperial College, London

9 May 2008   

High harmonic generation (HHG) in gases driven by intense, femtosecond laser pulses provides a very promising source of coherent short wavelength radiation in the 5-100nm range. High harmonic radiation is the result of coherent "recollisions" of a laser driven electron wavepacket with its parent ion. A unique feature of this light is its very short pulse nature (down to ~0.1fs = 100 as) and its precise synchronisation with the driving laser pulse. This allows it to be used in pump-probe type studies (typically XUV+IR) to track ultrafast dynamics. A less-well known feature of HHG is that the electron recollision event can be used to image molecular structure and dynamics on the attosecond timescale and sub-Angstrom length scale.
This talk will review the production of HHG light as a coherent source for imaging and discuss some of the exciting developments in recent years on attosecond timescale dynamic measurements.

SEARCHES FOR EXTRA DIMENSIONS AT THE LHC

   Dr Tracey Berry   

Royal Holloway, University of London

2 May 2008   

The Large Hadron Collider (LHC) at CERN will become the world's largest - and highest energy - particle accelerator when it produces its first beams later this year. As well as finally yielding the elusive Higgs boson, the LHC could produce other novel species, from superpartner particles to tiny black holes.
Dr Berry will summarise the potential of the ATLAS and CMS experiments at the LHC to search for extra-dimensional models, describing their distinctive experimental signatures and the expected discovery limits. She will discuss the reaches expected in different channels and proposals to distinguish these models from other new physics scenarios.

MOLECULAR MOTORS

   Dr John Sleep   

King's College, London

25 April 2008   

Motors convert chemical energy into mechanical work and in the biological realm this process occurs most obviously in muscles through the action of the protein myosin on adenosine triphosphate. In fact most of the 39 distinct myosins in the human genome are responsible for motions within non-muscle cells and they display a wide range of properties. Moreover, there are two other classes of linear motor, kinesins and dyneins, each example of which has a precise function in the body.

BOSE-EINSTEIN CONDENSATION WITH TUNABLE INTERACTIONS: FROM SOLITONS TO MOLECULES

   Dr Simon Cornish   

University of Durham

14 March 2008   

The last decade has witnessed an explosion of research in the field of quantum degenerate gases. Experimental activity continues to progress at a remarkable rate as existing techniques are extended and combined in ever richer systems. Recent "hot topics" include the study of Feshbach resonances, the realization of quantum degenerate mixtures and the investigation of quantum degenerate gases in optical lattice potentials. This talk will outline the development and motivation behind two Bose-Einstein condensation experiments at Durham which aim to explore these exciting topics.

NONLINEAR DYNAMICS OF THE CARDIOVASCULAR SYSTEM

   Prof Peter McClintock   

University of Lancaster

29 February 2008   

The cardiovascular system may be considered to comprise many coupled nonlinear oscillators, differing in their physiological origins, whose behaviour can be inferred by applying various techniques of nonlinear, stochastic and fractal analysis. Models thus obtained of the cardiovascular system, and the interaction between the cardiac and respiratory systems, allow the identification of age-related changes, and promise a powerful tool for the solution of a long-standing challenge: the development of new diagnostic techniques based upon non-invasive measurements.

LAB-BASED ULTRAFAST SOFT X-RAYS: THE AFFORDABLE ALTERNATIVE TO SYNCROTRONS

   Dr Sarah Stebbings   

University of Southampton

22 February 2008   

The production of coherent, ultrafast x-rays via a process known as high harmonic generation offers many potential applications across a wide range of scientific endeavours. Their wavelengths (e.g. 1 - 40 nm) and sub-femtosecond (i.e. < 10^-15 seconds) pulse duration make them ideal for probing the structure of nanoscale objects as well as studying ultrafast electron dynamics in real time, thus opening up new areas of study in science. All of this comes at a fraction of the cost and size of alternative x-ray sources such as synchrotrons and free electron lasers. In this talk, I will discuss how we produce and optimise our x-ray beam, present some of our results and discuss our plans for future experiments.

NEW EYES ON THE UNIVERSE: ASTRONOMICAL INSTRUMENTATION IN THE 21ST CENTURY

   Prof Ray Sharples   

University of Durham

8 February 2008   

Progress in astronomy is closely coupled to developments in astronomical technology and instrumentation. This talk will review the recent advances which have been made in developing instruments for the current generation of large 8-10m diameter ground-based telescopes, and the challenges posed by future extremely large (20-40m diameter) telescopes. Specific technical advances will be illustrated via new instruments being developed at the Centre for Advanced Instrumentation in Durham.

VELOCITY-MAP IMAGING OF CHEMICAL EVENTS

   Dr Claire Vallance   

University of Oxford

1 February 2008   

Work in the field of chemical reaction dynamics is aimed at understanding the detailed physics underlying chemical reactivity. In recent years, the field has been revolutionised by the introduction of velocity-map imaging, a technique which provides a direct snapshot of the reaction product scattering distribution with single particle resolution. This talk will outline the history and capabilities of the velocity-map imaging technique, with examples taken from research carried out within our group, and will also preview some future developments.

SCULPTING BEHAVIOUR BY EVOLUTION

   Dr Mario de Bono   

University of Cambridge

25 January 2008   

Out in the wild the nematode Caenorhabditis elegans lives by eating bacteria in rotting vegetation. Over the past 40 years this worm has been domesticated in the lab and is now probably the best understood multicellular organism. We are studying how its network of precisely 302 neurons allows it to forage for food, and how, at the level of molecules and neural circutis, foraging behaviour evolves across wild populations. I will focus in particular on responses to food and ambient oxygen.

SUPER SUPERCRITICAL FLUIDS

   Dr David Smith   

University of Southampton

18 January 2008   

(Sadly, David has forgotten to let me have an abstract for his talk, but I think I can remember the gist...)
Supercritical fluids are the moaning Minnies of the fluid world, worked up into such a heated, high pressure lather that they can no longer distinguish substance from hot air. Their cutting criticism penetrates deeply into nanoscale structures, transporting bile and venom to hitherto inaccessible recesses. Shunning superficial attractions, supercritical fluids may know the cost of everything and the value of nothing, but they are about to revolutionize the deposition of functional nanostructured films, facilitate a new class of hitherto diffusion-limited chemical reactions, and single-handedly save the world from global warming.

ROUGH GUIDE TO THE MOON AND MARS

   Prof Mike Lockwood   

University of Southampton

11 January 2008   

This talk will provide a survival guide for those of you thinking of venturing into inter-planetary space, and an exploration of the many and diverse hazards that the intrepid space traveller must risk or endure.

OPTICAL SCULPTING AND OPTICAL BINDING

   Prof Colin Bain   

University of Durham

14 December 2007   

This talk will describe two areas of current research in which we use optical forces to control the organisation and shape of objects on micron and sub-micron length-scales.
The surface tension of oil droplets is normally many orders of magnitude larger than the force constant of optical tweezers, with the result that small emulsion droplets are not measurably deformed by focussed light beams. Close to microemulsion phase boundaries, the interfacial tension of oil-in-water emulsions drops to ultralow values. Optical tweezers can then be used to deform micron-sized oil droplets into predetermined shapes. When a single oil drop is divided into two with a pair of optical tweezers, the daughter drop remains connected to the parent drop by an invisible thread of oil of nanometric diameter. Optical pressure can be used to drive flow between droplets connected by such a nanothread. Strategies can be developed for creating 3-way junctions between nanothreads and for making closed loops of droplets connected by threads.
The technique of optical trapping, in which scattering of light by single particle leads to a force on that particle, is well-known. Multiple scattering of laser light can also give rise to a force between particles, a phenomenon known as optical binding. Optical binding can result in spontaneous creation of ordered particle arrays, known as ‘optical matter’. Interesting dynamical effects, with analogies to atomic crystals, are observed.

GLOBAL REMOTE SENSING OF THE ATMOSPHERIC ELECTROMAGNETIC ENVIRONMENT

   Dr Martin Füllekrug   

University of Bath

7 December 2007   

The atmospheric electromagnetic environment of the Earth is explored with low frequency electromagnetic waves. The locations of lightning discharges around the globe are determined with a global magnetometer network to monitor the temporal and spatial evolution of particularly intense thunderstorms. Above these thunderstorms, an exotic type of lightning occurs, denoted sprites. Sprites are associated with electrical breakdown in the mesosphere and electrically couple the troposphere with the ionosphere. Sprites are a new element in the global atmospheric electric circuit which may play a critical role in fair weather cloud formation.

HARNESSING LIGHT WITH PLASMONS

   Prof Bill Barnes   

University of Exeter

30 November 2007   

In this colloquium we will look at the physics underlying plasmonics - and at some of the features that make it an attractive and exciting topic of current research.

TESTING TIME-REVERSAL SYMMETRY

   Dr Ben Sauer   

Imperial College, London

23 November 2007   

Many extensions to the Standard Model violate time reversal symmetry. In particular, Supersymmetry predicts rather large time reversal violating electric dipole moments of fundamental particles. I will describe our experiment to search for T violation using YbF molecules, a particularly sensitive system. I will describe our new molecular beam techniques for sensitive measurements of E and B fields, as well as discussing the current status of the T violation experiment.

A FAT-FREE THREE-STEP GUIDE TO SURFACE PLASMON POLARITONS

   Dr Dominic Zerulla   

University College, Dublin

16 November 2007   

Surface Plasmons (SPs), widely recognized in the field of surface science following the pioneering work by Ritchie, are electromagnetic surface waves propagating along the interface of two materials with dielectric functions of opposite sign. They are essentially light waves that are trapped on the surface as a result of interactions between the illuminating wave and the free electrons of the conductor, and are called Surface Plasmon Polaritons (SPPs) to reflect this hybrid nature. Recent advances in fabrication technologies have created new opportunities to control SPP properties to reveal new aspects of their underlying science, and to tailor them for specific applications.

After a short introduction into SPP excitation, this talk will focus on SPP propagation on nanostructured surfaces, tuneability of SPPs arising from metamaterials and focusing aspects of SPPs.

VECSELS: COLOURFUL SOLID-STATE LASERS

   Dr Jennifer Hastie   

University of Strathclyde

2 November 2007   

Vertical external cavity surface emitting lasers (VECSELs) are optically-pumped solid-state lasers with the advantage of a semiconductor gain region. High brightness combined with the wavelength flexibility available through semiconductor bandgap engineering leads to a versatile laser source that may be tailored to a particular application, from the ultraviolet to the mid-infrared. An overview of these lasers will be given with attention to thermal management and spectral coverage, focussing on the red and ultraviolet.

ENGINEERING IN YACHT DESIGN FOR THE 2007 AMERICA'S CUP

   Mr Ian Campbell   

University of Southampton

26 October 2007   

The University of Southampton has had a long association with the America's Cup through the work of the Wolfson Unit. For the 2007 Cup Ian Campbell, a Wolfson Unit research engineer, became part of the Luna Rossa challenge design team, with particular responsibilities for their experimental research programmes. Here, he will give an overview of the engineering development work involved in designing the yachts, which is aimed at improving their performance.

WHY AREN'T THERE ANY... MAGNETIC LIQUIDS?

   Prof Kevin O'Grady   

University of York

19 October 2007   

Ferrofluids - paramagnetic suspensions of magnetic nanoparticles - exploit a bizarre range of physical phenomena, forming spontaneous corrugations in the presence of an external field, showing thermal convection when heated above the Curie temperature, and adhering to magnetized moving parts. As a result, they also find an extremely diverse variety of scientific and industrial applications, from coolants and lubricants to adaptive shock absorbers and actuators. With the aid of a number of practical demonstrations, Prof O'Grady will discuss the many fascinating aspects of these remarkable fluids.

SEISMOLOGY OF SOLAR ACTIVITY

   Prof Mike Thompson   

University of Sheffield

12 October 2007   

Helioseismology provides a unique probe of the solar interior. In this talk, Prof Thompson will discuss recent results from helioseismology in particular relating to temporal variations of the interior dynamics and the emergence of magnetic flux.

A CHIP-SCALE DIFFERENTIAL ATOMIC MAGNETOMETER

   Dr Eleanor Hodby   

NIST, Boulder

5 October 2007   

This talk will give a brief overview of the chip-scale atomic devices work at NIST, Colorado, which began with the development of an atomic clock no larger than a grain of rice. Dr Hodby will discuss the principles of atomic magnetometry before describing the design and operation of the new chip-scale differential magnetometer in detail.

QUANTUM OPTICS WITH MACROMOLECULES: BALLS, STRINGS AND LITTLE ELEPHANTS

   Prof Markus Arndt   

University of Vienna

15 June 2007   

Research on matter waves is currently a thriving field of quantum physics, and coherence experiments with complex objects are of particular interest for exploring the quantum-to-classical transition, for precisely measuring molecular properties, and for testing new models of space-time.
Prof Arndt's group has performed the first experimental realization of a new interferometer type which is particularly well suited for demonstrating the wave-particle duality of "large things". Here, Prof Arndt will report experiments using the new device with molecular balls, pancakes and strings, and discuss the conditions needed to see even the interference of a small 'molecular elephant' in the near future. Various applications will be considered, regarding both the foundations of physics and measurements in physical chemistry.

ATOMS STRIPPED (ALMOST) BARE: THE PHYSICS OF HIGHLY CHARGED IONS

   Dr David Crosby   

University of Oxford

8 June 2007   

Highly charged ions are atoms that have been stripped of most of their electrons. The comparatively high ionization energies required in order to produce such systems mean that highly charged ions occur in association with many hot and violent phenomena such as active galactic nuclei and magnetically confined fusion plasmas. Highly charged ions also represent an extreme of atomic physics where relativistic and quantum electrodynamic effects lead to changes of the usual rules and expectations. In this talk, Dr Crosby will provide an overview of the physics of highly charged ions and some of their applications. He will also describe a particular device used for the study of highly charged ions, the electron beam ion trap (EBIT), and discuss experiments that seek to test aspects of fundamental atomic physics using highly charged ions.

THE ENIGMA MACHINE AND THE BOMBE

   Mr Frank Carter   

Bletchley Park Trust

1 June 2007   

Just outside what is now Milton Keynes, and perhaps strategically mid-way between Oxford and Cambridge, Bletchley Park was the centre of one of the most remarkable achievements of the Second World War: the repeated breaking of the German military signals codes. These heroic efforts, by a disparate band of academics, emigres, and servicemen and women, represented a colossal activity that Churchill considered to have changed the direction of the war; yet, despite the involvement of many thousands of people, the entire operation remained an untold secret until the 1970s. The incredible story is also that of the invention of the computer, which developed from the machines developed at Bletchley as crucial parts of the code-breaking processes.
Mr Carter will focus on one major aspect of Bletchley's extensive wartime history: the breaking of the Enigma ciphers and the development of the machines to do this. He will begin with a brief account of the history of the Enigma machine and how it was used operationally by the German Armed Forces during WWII. He will then explain the design of, and rationale behind, the remarkable 'Bombe' that was developed to break the Enigma ciphers by Alan Turing and Gordon Welchman, from an original pre-war machine invented by Polish mathematicians. The operation of the Bombe will be illustrated with the aid of a small electrical model.

FROM HEP TO HEP: HIGH ENERGY PHYSICS TO HIGHLY ENTANGLED PROTEINS

   Prof Dick Blankenbecler   

Stanford University

18 May 2007   

The concept of atoms as particles is familiar to many, however at the microscopic level classical physics breaks down, and we enter the wave-like realm of quantum mechanics. If vapours of bosons are cold and dense enough a phase transition occurs in which all of the atoms coalesce into the same (lowest energy) quantum state – a Bose-Einstein condensate (BEC), in which all of the atomic wave-functions are coherent. These "atom lasers" are extremely cold (~50nK) and allow textbook quantum mechanics to be played out on a simple CCD camera.
Dr Arnold will give an overview of the processes required to obtain BEC, briefly sidetracking into atomic lenses, before discussing the construction of the Strathclyde 10cm diameter storage ring for cold atoms and BECs. He will then present recent experimental BEC/storage ring results from his group, including a gravitational beamsplitter for BECs. The Strathclyde system will be ideal for studying condensate collisions and for precise Sagnac interferometry.

GOING ROUND THE BEND WITH BOSE-EINSTEIN CONDENSATES

   Dr Aidan Arnold   

University of Strathclyde

11 May 2007   

The concept of atoms as particles is familiar to many, however at the microscopic level classical physics breaks down, and we enter the wave-like realm of quantum mechanics. If vapours of bosons are cold and dense enough a phase transition occurs in which all of the atoms coalesce into the same (lowest energy) quantum state – a Bose-Einstein condensate (BEC), in which all of the atomic wave-functions are coherent. These "atom lasers" are extremely cold (~50nK) and allow textbook quantum mechanics to be played out on a simple CCD camera.
Dr Arnold will give an overview of the processes required to obtain BEC, briefly sidetracking into atomic lenses, before discussing the construction of the Strathclyde 10cm diameter storage ring for cold atoms and BECs. He will then present recent experimental BEC/storage ring results from his group, including a gravitational beamsplitter for BECs. The Strathclyde system will be ideal for studying condensate collisions and for precise Sagnac interferometry.

MAXIMIZING ENTROPY FOR FUN AND PROFIT

   Dr Geoff Daniell   

University of Southampton

4 May 2007   

Geoff's talk will describe the background justification to the Maximum Entropy method of assigning values to probabilities. He will then give very rapid and superficial accounts of three applications: Statistical Mechanics, The National Lottery and Data Processing.
No previous knowledge will be assumed and the talk should be understandable and of interest to all physicists including undergraduates (in fact some of the material is taken from Geoff's lectures on thermal physics).

NOVEL TOOLS FOR OCEAN SCIENCE

   Prof Gwyn Griffiths   

University of Southampton

20 April 2007   

Progress in ocean science is often dependent on our capacity to make observations. The Underwater Systems Laboratory develops new platforms, such as autonomous underwater vehicles, that are capable of carrying sensors to otherwise inaccessible parts of the ocean, for example beneath sea ice and floating ice sheets. Remotely operated vehicles provide an intervention capability for observation and sample collection in the deep ocean, while underwater gliders enable unattended long endurance measurements at low cost.
However, for many parameters no suitable in situ sensor yet exists. USL works closely with several academic schools to devise new sensors, often through cosupervised students. Recent examples include measuring methane using a Surface Plasmon Resonance device and characterising phytoplankton species using automated cytometry and electrical impedance spectroscopy using microchips designed and constructed at the University.
The talk will cover the science drivers, examples of advances in ocean science from the developments at USL, elements of the technologies employed and some of the gaps in capability and will conclude with an outline of our core programme for the next 5 years.

OPTICAL TWEEZERS: MICROBUBBLES AND NANOTUBES

   Dr Phil Jones   

University College, London

16 March 2007   

Optical tweezers - that is a single beam optical dipole trap for microscopic objects - have many applications across the physical, chemical and life sciences. In this talk I will review how optical tweezers work before discussing, and presenting results from, our recent experiments with two technologically interesting optically trappable objects: microscopic coated gas bubbles and carbon nanotubes.

THE DIAMOND SYNCHROTRON LIGHT SOURCE

   Dr Sarnjeet Dhesi   

Rutherford-Appleton Laboratory

2 March 2007   

The Diamond 3GeV synchrotron, which opened to its first scientific users last month, is the largest and most expensive UK science facility of recent decades. The third-generation light source uses arrays of magnets to generate extremely intense, narrow beams of radiation at energies from meV IR through to >40keV x-rays, 10,000 times brighter than Daresbury, for research applications across the physical, life, earth and environmental sciences.

QUANTUM STATE ENGINEERING WITH SINGLE ATOMS, PHOTONS AND ELECTRONS

   Dr Matt Jones   

University of Durham

16 February 2007   

How big can a quantum state be? Answering this question has turned into an exciting area of research spanning quantum optics, atomic physics and condensed matter. One approach is to try to build up many-body quantum states from individual quantum systems. Dr Jones will present recent experimental results on controlling the quantum state of single rubidium atoms trapped in an optical tweezer, and will describe how we can couple these atoms to another quantum system - single photons - in a controlled way. A second "top-down" approach is to try to access and control the state of individual particles in a larger, interacting many-body system. How this might be done using electron transport in ultra-cold strontium atoms will be outlined.

WEIGHING THE ANTIPROTON: PRECISION LASER SPECTROSCOPY OF ANTIPROTONIC HELIUM ATOMS

   Prof Ryugo Hayano   

CERN & University of Tokyo

9 February 2007   

Antiprotonic helium is a metastable three-body neutral atom consisting of an antiproton, a helium nucleus and an electron. The antiproton, which normally annihilates within a few picoseconds when injected into matter, can be "stored" in the antiprotonic helium atom for up to several microseconds, and laser spectroscopy is possible within this time window. From the laser transition frequency, the antiproton-to-electron mass ratio can be deduced, and in our recent measurement, we determined the antiproton-to-electron mass ratio to be 1836.152674(5). In the seminar, I will discuss how we discovered this exotic system, how we observe the laser resonance, and implications of our recent results on the CODATA fundamental constant adjustments as well as on the matter-antimatter symmetry tests.

COLOUR CENTRES IN DIAMOND AS PRACTICAL SINGLE-PHOTON SOURCES

   Dr Francois Treussart   

Ecole Normale Superieur de Cachan

2 February 2007   

Nitrogen-Vacancy (N-V) colour centres in diamond show stable room temperature photoluminescence of unsurpassed efficiency and, optically excited in a pulsed fashion, offer clock-triggered single-photon pulses. Efficient extraction of the emitted photons is however thwarted by the high diamond refractive index, for refraction at the sample interface leads to a small collection solid angle due to total internal reflection, and strong optical aberrations. An efficient solution uses sub-wavelength diamond nanocrystals, rendering refraction irrelevant and allowing the colour centres to radiate essentially as if they were point sources in air.
This talk will describe a "turn-key" single-photon source based on (N-V) colour centre photoluminescence inside dispersed diamond nanocrystals. Following J. A. Wheeler’s seminal ideas, we have used the emitted single photons to realize a wave-particle delayed-choice experiment based on a Mach-Zehnder interferometer. The measurement at the output of the interferometer is randomly switched between either the registration of the "which-path" information for the photon or the observation of the interference fringes. As predicted by quantum mechanics, we observe no difference between a so-called "normal-choice" and a "delayed-choice" experiment where the switching process takes place only after the photon passes the first beamsplitter of the interferometer.
We have also investigated the application of our single-photon sources to open-air quantum key distribution (QKD). Broad-band colour centre emission in the (N-V) system precludes day-light QKD operation, but other colour centres in diamond, related to nickel impurities, show striking new features, with narrow band emission around 800 nm that is almost entirely concentrated in the zero phonon line even at room temperature. With a short photon emission lifetime around 2 ns, these sources pave the way to efficient open-air single-photon QKD in day-light operating conditions.

BLUE SKY RESEARCH: THE POLARIZATION OF DAYLIGHT

   Dr Mark Dennis   

University of Southampton

19 January 2007   

A little-known fact is that the polarization of the natural blue sky of daylight contains polarization singularities (polarization vortices), where the degree of polarization vanishes. They were discovered by observation in the 1800s, explained approximately by Rayleigh scattering, and their detailed prediction was one of the successes of Chandrasekhar's radiative transfer theory in the 1950s. Here, Dr Dennis will discuss their topological properties: as simple examples of polarization singularities, they organize the pattern of polarization in skylight. A simple mathematical ansatz is consistent both with observations and Chandrasekhar's theory. Dr Dennis will also discuss connections between this work and polarization singularities in the electromagnetism of dielectrics, and in spatially-varying random polarization patterns.

HOW CAN WE SOLVE THE MATHS PROBLEM?

   Dr David Acheson   

University of Oxford

12 January 2007   

Why are so many people scared stiff of mathematics? All too often, the real truth is that they have never been allowed anywhere near it. In this lecture, Dr Acheson will suggest how anyone can appreciate something of mathematics at its best, including elegant lines of reasoning, surprising results and remarkable applications, ranging from the dynamics of the electric guitar to whether mathematics can explain the legendary Indian Rope Trick.

FROM EINSTEIN'S INTUITION TO QUANTUM BITS: A NEW QUANTUM AGE?

   Prof Alain Aspect   

Institut d'Optique, Université de Paris-Sud

8 December 2006   

According to quantum mechanics, the Einstein-Podolsky-Rosen paradox predicts that two particles may be connected by a 'ghostly action at a distance', whereby a measurement on one particle instantly determines the state of the other, even before light could have travelled between the two. This scenario drives right to the heart of quantum mechanics, suggesting that there might be pre-determined 'hidden variables' that the quantum measurement process simply reveals. John Bell's analysis of this interpretation indicated that the existence or otherwise of hidden variables could be determined experimentally ("Bell's inequalities"). The experiment was then performed in an exceptionally clear and elegant fashion by Aspect, Dalibard and Roger in 1982. "The results," read the abstract, "are in good agreement with quantum mechanical predictions but violate Bell's inequalities by 5 standard deviations." The experiment is one of the very few from the last 50 years to enter our standard textbooks, and paved the way for the remarkable new technique of quantum cryptography.

SELF-ORGANIZED NANOPARTICLE ASSEMBLIES: A PANOPLY OF PATTERNS

   Prof Philip Moriarty   

University of Nottingham

1 December 2006   

Nanoparticle-solvent films deposited on solid substrates are associated with a rich dynamic behaviour which gives rise to a wide variety of striking self-organised patterns. Although close-to-equilibrium self-assembly of nanoparticle arrays has been studied in some depth, there has been rather less work on solvent-nanoparticle systems driven far from equilibrium (via, for example, spin coating). In the far-from-equilibrium regime, a remarkably broad array of intricate, spatially correlated patterns form including "foam-like" cellular networks, labyrinthine structures similar to those formed in spinodal decomposition of binary fluids, and well-defined fractal morphologies. I shall focus on our recent results in two areas: (i) "coerced coaresening" of nanoparticle arrays where the system is mechanically driven towards equilibrium, and (ii) the use of scanning probe-defined silicon oxide patterns to direct solvent dewetting and thus form colloidal nanoparticle corrals.

COLD ANTIHYDROGEN

   Prof Jochen Walz   

Johannes-Gutenberg Universität Mainz

24 November 2006   

Cold antihydrogen atoms have been produced at CERN's Antiproton Decelerator (AD) by mixing trapped antiprotons and positrons. The internal structure of antihydrogen atoms has been probed and their velocity has been measured. This talk will discuss experiments of the ATRAP collaboration.
Future high-resolution laser-spectroscopy of antihydrogen in a magnetic trap can provide extremely precise tests of the fundamental symmetry between matter and antimatter (CPT symmetry). Yet another exciting long-term perspective is that ultra-cold antihydrogen atoms might enable the first measurement of the gravitational acceleration of antimatter. For both types of experiment cooling of antihydrogen atoms is essential. This talk will discuss conventional and novel cooling methods.

COLD MOLECULES AND ULTRACOLD CHEMISTRY

   Prof Tim Softley   

University of Oxford

17 November 2006   

A range of methods being developed in our laboratory for the production of cold and ultracold molecules in the gas phase (T< 1K), including ions, neutrals and Rydberg molecules, will be discussed, and I will report on progress towards collisional studies with these translationally cold species.

THE DARK SIDE OF THE UNIVERSE

   Prof Joe Silk   

University of Oxford

10 November 2006   

One of the greatest mysteries in the cosmos is that it is mostly dark. That is, not only is the observed night-sky dark, but also most of the matter in the universe - whose existence is clearly inferred from the observations - is dark. For every atom visible in planets, stars and galaxies today there exists at least five or six times as much "Dark Matter" in the universe. Astronomers today are seeking to unravel the nature of this mysterious, but pervasive dark matter, and determine whether it can ever be detected.
I will review the current status of these searches.

SLOW LIGHT IN PHOTONIC CRYSTAL WAVEGUIDES

   Prof Thomas Krauss   

University of St Andrews

3 November 2006   

In an age where faster is better, the proposition to improve photonic devices by slowing light down seems an odd idea. Nevertheless, slow light offers many opportunities, based on the fact that it yields stronger light-matter interactions. Increased linear and nonlinear effects for switches and modulators, as well as the prospect of photonic memory are motivating much research in this area.
Slow light can be created in dielectric materials via resonances in cavities or in photonic crystals. In the case of dielectric structures, the refractive index contrast is the key parameter determining the performance of the system, so high refractive index structures such as photonic crystals appear particularly promising. While slow light in photonic crystals has been observed by a variety of authors, the operating point is typically near the edge of the Brillouin zone, which is naturally dispersive. Slow light in photonic crystals therefore tends to coincide with high dispersion, which removes most of the advantages and severely limits the bandwidth that can be utilised. In fact, dispersive broadening has been observed to outweigh the pulse compression one would otherwise expect.
Luckily, the large parameter-space available in photonic crystal waveguides allows the design of waveguides with controlled dispersion. We also found a slow light regime in a W2 waveguide away from the band-edge that exhibits slow light over a considerable bandwidth and that has allowed us to demonstrate pulse compression, commensurate with the reduction in group velocity, by a factor of 25.
Another aspect of slow light in photonic crystals is that of propagation loss. Since loss scales with the square of disorder, it is essential to refine the technology to its absolute limit. We have achieved propagation losses in W1-type waveguides of below 5 dB/cm. Furthermore, we observe losses to scale linearly with slowdown factor, which is encouraging given that several authors have previously claimed an S2 dependence. This indicates that devices exploiting slow light phenomena are indeed realistic.

A QUANTUM APPROACH TO FRICTION

   Prof Steve Barnett   

University of Strathclyde

27 October 2006   

As students we learn how to introduce frictional losses into mechanics as a slowing force proportional to a particle's velocity. This leads, of course, to a steady state for unforced systems in which the particle is stationary. At a more microscopic level, however, thermal effects on the motion cannot be ignored and we enter a regime in which Brownian motion dominates. We can describe this in a simple way by adding a fluctuating random force, the effect of which is to ensure a never ending thermal agitation. The description of this phenomenon in terms of molecular motion was, of course, one Einstein's great contributions in 1905.
At the level of quantum dynamics, the description of friction is anything but straightforward. At the simplest level we run into difficulties with commutation relations. Analyses based on model environments inevitably seem to lead either to memory effects or to unphysical heating or thermal runaway, neither of which is present in classical dynamics. I shall describe a simple approach to modeling quantum friction based on the physics of collisions as measurements. The resulting dynamics has many of the appealing features of the classical Brownian motion but with some inevitable quantum subtleties.

THE DAZZLER: A PROGRAMMABLE ACOUSTO-OPTIC DISPERSIVE FILTER

   Pierre Tournois & Daniel Kaplan   

Fastlite, Paris

20 October 2006   

The talk will describe how, with only a simple acousto-optic crystal in line in the laser beam, one can program a precisely known spectral phase into a broadband femtosecond pulse. Various applications of this device will be discussed. We shall emphasize its recent use to quantitative phase measurements, allowing to switch between methods such as autocorrelation, SPIDER, FROG, etc., without changing the optical set-up.

ANCIENT ASTRONOMY: THE EGYPTIAN VIEW OF THE SKY

   Sarah Symons   

University of Leicester

13 October 2006   

Astronomical activity in ancient Egypt is frequently linked with religious ritual, but several forms of astronomical information (such as astronomical diagrams and star clocks) contain evidence of long-term observational practices. We will look at textual sources, astronomical instruments, and graphical representations of the sky, and discuss the extent and applications of astronomical knowledge in ancient Egypt.

JOHN HERSCHEL - ASTRONOMER, ARTIST, AND MUCH MORE

   Brian Warner   

University of Cape Town

28 July 2006   

Son of the more famous William Herschel, John Herschel was one of the most extraordinary polymaths in the 9th centure. The lexture will describe and illustrate his life as an astronomer, mathematician, physicist, artist, inventor and generally all-round good chap.

TIMING IS EVERYTHING: FEMTOSECOND PULSE CONTROL ON A MULTI-BEAM LIGHT SOURCE

   Graeme Hirst   

Rutherford Appleton Laboratory

16 June 2006   

The next generation of accelerator-based light sources will deliver broadly tunable radiation pulses in the femtosecond regime. These will be used to extend existing laser techniques and to develop new science in previously inaccessible parts of the spectrum.

However this will only be possible if the timing of the pulses can be managed at the femtosecond level across installations which will be hundreds or thousands of metres in size. This talk will outline the substantial challenges arising from this requirement and will describe some of the creative solutions, based largely on modern laser and fibre-optic technology, which are being developed to meet it.

BETA-SHEET PROTEIN FIBRILS: MONEY FOR OLD ROPE?

   Cait MacPhee   

University of Edinburgh

2 June 2006   

Beta-sheet protein fibrils are linear and unusually stable aggregates most commonly associated with a number of degenerative diseases, including Alzheimer's, Parkinson's and type-II diabetes. In disease states their formation is typically a result of the impairment of metabolic pathways or cellular function. In contrast to this villainous activity, recent evidence suggests that they may also have beneficial roles in nature including controlling osmotic flow, mediating surface adhesion, and moderating surface tension. These physico-mechanical properties suggest their utility in a wide range of surface applications and their self-assembly ability suggests their use as scaffolds in the development of novel materials. This talk will describe recent advances in protein nanotechnology, and explore the properties of natural and artificial fibrillar protein scaffolds that may make them useful as self-assembling nanoscale materials.

THE PATH TO FUSION POWER

   Chris Llewellyn-Smith   

UKAEA Culham

26 May 2006   

Fusion, which powers the sun and stars, is potentially an environmentally responsible and intrinsically safe source of essentially limitless energy. The Joint European Torus (JET) has produced 16 MW of fusion power, and construction of a power station sized device called ITER (International Tokamak Experimental Reactor), which should produce at least 500 MW, is about to begin. An International Fusion Materials Irradiation Facility (IFMIF) is also needed to test materials that will have to stand up to years of intense neutron bombardment in a fusion power station. Given its potential attarcations (which include essentially limitless fuel, and the absence of green-house gas, or other emissions, and of long-lived radio-active by-products), and that the economics of fusion power look acceptable, the time has come to develop fusion as rapidly as reasonably possible. The status and potential advantages of fusion will be described, together with the outstanding challenges, remaining steps and timetable for developing fusion power.

OPTICAL MICROMANIPULATION TAKES HOLD

   Kishan Dholakia   

University of St Andrews

12 May 2006   

Optical tweezing is a powerful non-contact technique where micrometre sized particles can be grabbed, moved and generally manipulated solely with light. Optical tweezers have forged an important bridge between physics, chemistry and biology. In recent years there has been a proliferation of activity in this area, fuelled, in part, by the recognition that we need to advance the “optical toolkit” particularly for microfluidic environments.

In this talk, Prof Dholakia will give an overview of this technique and discuss a variety of current important themes in this field including creation of large scale optical landscapes, trapping and organisation on a surface including the use of surface plasmons and cavity enhanced fields. Particle-particle interactions may lead to "optical binding" which may lead to self -assembly. Finally (and time permitting), biophysics applications will be described including optical sorting and photoporation of cells.

MOLECULAR DIODES AND SINGLE MOLECULE ELECTRONICS

   Geoff Ashwell   

Cranfield University

5 May 2006   

To mimic the functions of silicon-based devices it is necessary to make electrical contact to molecules that self-organise, the shortest active sequence being metal|donor-acceptor|metal. It is described as a molecular diode when the organic moieties are linked via an electron bridge and as a rectifying junction when they are simply in physical contact. There are few examples and the published rectification ratios are too small to have any real significance, the values being typically 2-30 at ±1 V for Langmuir-Blodgett and self-assembled monolayers contacted by non-oxidisable electrodes. However, new methods of self-organisation have provided greatly improved behaviour with rectification ratios in excess of 3000 at ±1 V for Au|Au-S-C₁₀H₂₀-A⁺-π-D|D^-|Au devices where a cationic acceptor-(π-bridge)-donor molecule is ionically coupled with an anionic donor. Rectification ratios from these ultra-thin structures are on a par with electrical asymmetries reported for metal-insulator-metal devices where oxide-induced Schottky barriers dominate the behaviour.

The properties of novel rectifying molecules will be presented together with recent data from studies on prefabricated nanoscale structures for single molecule electronics.

NANOPLASMONICS: GENERATION AND CONTROL OF NANOSCALE OPTICAL FIELDS

   Mark Stockman   

Georgia State University

24 March 2006   

Nanoplasmonic phenomena are based on the resonant excitation of surface plasmons, causing highly enhanced and localized optical fields on the nano-scale. These fields induce a multitude of enhanced optical effects, in particular, surface enhanced Raman scattering (SERS) including single-molecule SERS, enhanced second- and third-harmonic generation, and enhanced two-photon electron emission from nanostructured surfaces, with many existing and prospective applications in nanoprobing, ultrasensitive detection and biomedical monitoring. This talk will include a broad introduction to the topic and also certain forefront, focus areas based partially on original contributions, including ultrafast, coherent, nonlinear, and stimulated phenomena.

PLANAR NANO-STRUCTURED META-MATERIALS

   Nikolay Zheludev   

University of Southampton

17 March 2006