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MM: Metall- und Materialphysik
MM 19: Electronic Properties I
MM 19.2: Talk
Tuesday, March 28, 2006, 16:45–17:00, IFW B
Cold-atom systems as solid-state simulators: the issue of trapping — •Chris Hooley1 and Jorge Quintanilla2 — 1School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, U.K. — 2ISIS facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, U.K.
Since the achievement of Bose-Einstein condensation in cold trapped gases in 1995, much attention has been devoted to experiments on such systems. Some of this work has involved the imposition of laser standing waves (so-called ‘optical lattices’) on the atom gas. It has been proposed that such set-ups could be used as simulators — or, more accurately, analogue computers — of the solid state, with the atoms playing the role of electrons and the laser standing wave playing the role of the periodic ionic potential. Immanuel Bloch poetically called these “artificial crystals of light”.
In this talk, we critically assess this proposal, concentrating in particular on one important difference between the atom-gas system and the solid state: in the solid state, electrons are confined by hard-wall boundaries, whereas in the atom-gas, they are more usually trapped by a smooth (often harmonic) effective potential. We demonstrate that this can make a qualitative difference to the behaviour of such systems, and explore how the ‘simulator’ proposal needs to be modified accordingly. We compare our results with recent experimental and numerical work.