Friday, February 23, 2007
Ultracold bosons in an optical lattice
Dilute atomic gases at a very low temperature exhibit an exotic quantum phenomenon known as Bose-Einstein condensation (BEC), which is now the subject of intense theoretical and experimental study. It is now possible to trap these Bose-condensed atoms in optical lattices -- a series of potential wells created by laser beams. In this system a zero-temperature quantum phase transition from a superfluid to a Mott insulator has been observed experimentally. This has opened up the possibility to experimentally study fundamental questions of modern solid state physics, atomic physics, quantum optics, and quantum information.
Recently, we investigated theoretically the zero-temperature phases of bosons trapped in a one-dimensional (1D) optical lattice with an explicit tunnel coupling to a Bose-condensed particle reservoir. Renormalization group analysis of this system has revealed the existence of three phases: a superfluid phase in which the 1D system becomes phase locked with the reservoir, a decoupled phase in which the 1D system behaves like a metal, and a Mott insulating phase. The states may be distinguished both by their low-energy excitation spectra and by their conduction properties.
Refreshments at 4:00 PM. Seminar begins at 4:10 PM.
Building 8 (Science Bldg.) - Room 241
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