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Quantum Control group |
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Quantum Control - undergraduate projectsProjects available this yearA tightrope-walking robot
Walking the high-wire is testing enough for humans, so building and programming a robot for the task is a particular
challenge. This project, centred around a simple mechanical structure, involves analysing the subtle physical problem,
designing a servo control strategy, programming the design into a Digital Signal Processing chip, and testing the system
experimentally. Optimal control theory design of composite pulse sequences for high-fidelity quantum control in atom interferometry
The Schrödinger equation is entirely deterministic. Provided that timescales are short compared with spontaneous emission,
it is therefore in principle possible to drive quantum systems between different states or superpositions with exquisite
precision. In practice, unfortunately, inhomogeneities tend to cause dephasing between different atoms of an ensemble.
Fortunately, as long as the inhomogeneities are repeatable, more complex quantum manipulations can be designed in which the
dephasing is cancelled. A range of such 'composite pulse' sequences has been developed for NMR applications, but they have
yet to be tailored to applications of atom interferometry.
Where to look out: strategies for visual collision avoidance in aviation
The service inquiry into the 2009 mid-air collision between two Air Cadet aircraft considered that the visual scan
recommended by the US FAA could take nearly a minute: "Not only is this an impracticable task but the scene would have
changed before the scan was finished." This analytical and computational project will apply models based upon the measured
performance of the eye to the problem of lookout, to evaluate the FAA technique and compare it with alternative strategies. Previous projectsAnalysis, design and construction of a Stirling engine heat pump
Hot air rises, and tall buildings thus tend to be warm at the top and cooler on lower floors that are also inconveniently distant from solar
heating of the roof. Energy bills could therefore often be reduced if heat could be transported downwards.
Investigating turbulence from wind turbines
Wind turbines are an attractive source of renewable energy on this windy island, but they are not without their complications.
Like any obstruction – and perhaps more so because they are not stationary – they cause turbulence in the air behind them, and
this is regarded as a potential hazard for both aircraft and wildlife. Although there have been many studies of the
turbine-generated turbulence, not least to determine the spacing required between different turbines within a wind farm, the
scale of the hazard to flight is still regarded as unknown.
Characterizing and optimizing the tin can telephone
The classic childhood telephone, comprising two tin cans and a length of string, provides an excellent demonstration
of wave transmission and transduction, and as such is open to straightforward but illuminating characterization and
subsequent optimization. The project will involve the production and systematic characterization of such a telephone,
its analysis in terms of wave propagation and impedance matching, and the subsequent design and manufacture of an
optimized device. If time permits, the same analysis may be extended to the mechanical gramophone. Mammalian hearing
This theoretical and literature-based project will seek to identify, compare and rank the mechanisms by which the mammalian ear distinguishes
between different frequencies, and by which it distinguishes between different times.
Analysis, design and construction of a Stirling engine heat pump
Hot air rises, and tall buildings thus tend to be warm at the top and cooler on lower floors that are also inconveniently distant from solar
heating of the roof. Energy bills could therefore often be reduced if heat could be transported downwards.
Laser spectroscopy and quantum effects in atomic rubidium
This project will involve assembling an external-cavity diode laser and using it to investigate the spectroscopy of atomic rubidium in a vapour
cell. Initial experiments with simple absorption spectroscopy will be refined by examining the interaction of counter-propagating laser beams
in a configuration known as saturated-absorption spectroscopy; this may then be further adapted to explore the curious quantum effects of induced
transparency, which are behind the 'slowing' of light to bicycle speed and, conversely, the possiblity of pulses that travel faster than the speed
of light. Absolute electronic determination of the speed of light
According to Maxwell's well-tested theories, the resonant frequency of a simple L-C circuit depends only upon the
component dimensions and the speed of light. By constructing from scratch a range of air-spaced capacitors and
inductors, measuring the resonant frequencies of their combinations, and carefully accounting for measurement and
end effects, this project allows the speed of light to be determined absolutely in a benchtop experiment. Enhanced laser stabilization, monitoring and control for cold atom experiments
Studies of ultracold atoms and quantum degenerate gases almost inevitably rely upon stabilized semiconductor lasers in the production
and manipulation of the ultracold species. Semiconductor lasers are electrically tunable, making them ideal for active stabilization,
but they are susceptible to 'mode-hopping' between longitudinal modes of the short semiconductor cavity; and the spectroscopic stabilization
is usually incapable of identifying without manual intervention the desired spectroscopic feature to which the wavelength should be stabilized.
This project will explore a range of possible techniques to address these shortcomings. The Grunt for the Red October
The silent underwater propulsion system given by Tom Clancy to the Russian submarine of his novel is far from
fiction: magneto-hydrodynamic propulsion has been an area of active research in recent years, but at a model
scale. Based upon the Lorentz force upon moving charges in a magnetic field, it generates thrust by passing
an electrical current through sea water. Holographic stereograms
Holographic stereograms are holograms that as well as re-creating 3D images are able to contain information from several frames,
such that when the hologram is tilted the image appears to move through a sequence of frames. They are created by careful exposure
of the holographic plate to a sequence of frames, restricting the field of exposure for each frame. The restricted exposure area
of each frame on the holographic plate causes a reduced amount of information to be stored on each frame and this causes restrictions
on the hologram’s properties (such as viewing angle and depth of field). This project aims to investigate the optical properties
associated with the production and viewing of holographic stereograms and optimise the production of a holographic stereogram using a
CW laser (which also presents interference troubles of its own in recording moving images). Where to find the English thermal
Rising columns of warm air provide the lift for cross-country glider pilots, and are well known to be associated
with particular ground features. Rocky outcrops, factories and car parks are all classic sources; but others may
be less obvious. This project will develop procedures for the automated analysis of satellite photographs to
identify and chart the predominant sources of thermals under various wind conditions, resulting in a map of
practical use to glider pilots. Cooking eggs in a sling
"The shepherds of Egypt," according to Mrs Beeton's Book of Household Management, "had a singular manner of cooking
eggs without the aid of fire. They placed them in a sling, which they turned so rapidly that the friction of the air
heated them to the exact point required for use." This project will examine, both experimentally and theoretically,
the potential effectiveness of such a method. Teaching computing to undergraduate physicists
Students typically arrive at university with computing skills sufficient to use the World-Wide Web, send emails, process documents
using Word, and use Excel and Powerpoint for basic analysis and presentations. The average student is not interested in computers beyond
the above, as this is all they need to do in ‘normal life’. It can be argued that teaching the students why we write a program in a given
way is important, giving the students more transferable skills; however from a small survey conducted the majority of the students asked
didn't want to learn how to program, and found the course turned them off doing any more programming or, in a couple of cases, of using
computers. This project will explore the variety of possible methods for teaching computing to undergraduate physicists, and will attempt
to apply proven rationales from academic literature to determine the most promising of these approaches. The Feynman reverse garden sprinkler
The ever-playful Richard Feynman derived great amusement by asking his colleagues which way a garden sprinkler
would turn if run backwards under water, so that water was drawn into the tube from which the jet normally emerges.
Many of those questioned felt that the sprinkler would rotate in the opposite direction, because the pressure
gradient at the open end would be reversed; others argued that the rotation would be unchanged, because the forces
acting on the inside of the curved pipe would be independent of the direction of flow. Feynman, of course, always
responded with the opposite argument to that expressed, thus ensuring that all were left in a quandry. Recreating the Logie Baird television
John Logie Baird's first television was a mechanical device, in which the image was scanned and subsequently
recreated by a system of suitably perforated spinning discs. Modern photodetectors and Fresnel lenses render the
original device's shortcoming of low optical throughput rather less serious. This project involves recreating
Logie Baird's first television system, taking the general scheme from contemporary material but leaving the
detailed design and analysis to the students' own creative innovation. Developing a sonic screwdriver
The acoustic gradient force - the equivalent of the optical dipole force used
for optical tweezers but with sound waves in place of light - has already been
used to levitate objects as large as steel balls. This project will explore the use
of ultrasound not only to trap but also to manipulate small particles and objects,
using tailored acoustic fields that are designed using the same techniques - cavity
mode analysis and holography - that are used in the optical analogue. In principle, it
should be possible to use ultrasound both to rotate trapped species and to form them
into acoustically-bonded structures. The Indian rope trick
It is a remarkable result of classical dynamics that a rod can be balanced on one end
simply by moving the point of contact up and down at an appropriate frequency. This theory
of parametric oscillation of the inverted pendulum predicts that a compound
pendulum, comprising a chain of connected rods, can also be balanced, and the principle
can ultimately be extended even to a flexible wire - although the precision needed in
the driving motion increases with the mechanical complexity. This project will involve
both experimental investigation and some theoretical analysis. Future possibilitiesPhase and frequency locking of diode lasers
The wavelength of a diode laser can be adjusted by varying the supply current. We aim with this project to take two similar diode
lasers and to adjust the current of the second ('slave') to bring the optical waveform into step with the first ('master'). Making
the two waveforms move at the same speed (frequency locking) is relatively straightforward, but the relative phase is then indeterminate.
Locking the waveforms in phase is trickier, partly because any appreciable frequency difference must first be overcome. By combining a
frequency and a phase 'error signal', using a cunning but straightforward detector arrangement, we shall develop make a simple and robust
way of locking the two lasers in phase. Once locked, interference fringes will be visible when the beams from the lasers are overlapped. Noise-cancellation for musical instruments
A boon to those wishing to practice at home! Active noise cancellation is used in expensive headsets and cars; this project will explore
its use, through an active device fitted to the end of a wind instrument, to reduce the sound produced without affecting the instrument
itself. As with most other active control problems, the trick is to measure the signal from a suitably placed microphone and apply it with
an appropriate amplitude and phase to a loudspeaker at the end of the instrument so as to cancel the sound of the instrument and reduce
the measured signal to zero. Digital stereo processing
Each of our ears hears sounds from both loudspeakers of a stereo music system; only with headphones is the true stereo of the original
recording properly reproduced. This project will apply digital signal processing to arrange for the 'left' signal to cancel at the right
ear and vice-versa - the principle behind the 'wideness' function on some ghetto-blasters. Although relatively straightforward for a fixed
geometry, some careful compromises must be made, for example, if the effect isn't to be critically dependent upon the position of the listener. Adiabatic pendulaThe pendulum is often a good classical model for the quantum oscillator. This project will investigate the process of adiabatic rapid passage, which is used in quantum manipulation schemes to invert an atomic population. Here, two pendula with different natural frequencies will be coupled by an electromagnet. Varying the magnet current in the right way should transfer the motion of one pendulum to the other; repeating the procedure transfers the motion back again. Stress analysis of a strapless evening gown
Scientific analysis and lateral thinking can bring remarkable innovations in even
the most day-to-day applications, allowing revolutionary designs ranging from the
use of Goretex and Lycra in technical clothing, to Howard Hughes' special cantilever
constructions - recorded memorably for posterity in Hitchcock's Vertigo - for
Jane Russell. This project will explore the structural requirements of fashion clothing,
the constraints upon how it is tailored, and the new possibilities offered by modern
fabrics and materials from Lycra and Kevlar to laid scrim laminates. |
School of Physics and Astronomy, University of Southampton
Highfield, Southampton, SO17 1BJ, United Kingdom
Tel: +44 (0)23 8059 2094, Fax: +44 (0)23 8059 3910