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AS A RESULT of the spectacular advances made in
state-of-the-art semiconductor growth and
fabrication technologies, it is now possible to
study billiards devices where the host material is so pure that electrons
travel along classical trajectories determined by the shape of the device cavity
rather than by material-induced scattering events.
This project investigates cavity shapes designed to induce chaos
(an exponential sensitivity to initial conditions) in the classical
electron trajectories. At milli-Kelvin temperatures, the quantum
wave properties of electrons becomes important, allowing the study
of 'quantum chaos' the quantum behaviour of classically
chaotic
systems. Not only does this work use a controlled physical system to
examine fundamental aspects of chaos and fractals, it also serves as
a demonstration of the precision with which semiconductor technology
can tune electronic properties of small devices.
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A collaboration with Nottingham University models the classical
and quantum behaviour of the electrical billiards. These studies are
being extended to, and compared with, wave chaos in light. Recent work
indicates that an analogous chaotic effect can occur in optical billiards (shaped
glass cavities). This phenomenon is being pursued both in terms of
fundamental research and potential applications.
Richard Newbury
& Richard Taylor
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