Ultracold quantum matter

Abstract:

We investigated the tunnelling dynamics of a zero-temperature Bose-Einstein condensate in configuration of four potential wells arranged in a loop. We found three interesting dynamic regimes: (a) flows of matter with small amplitude, (b) steady flow, and (c) forced flow of matter for large amplitudes. The regime of quantum self-confinement has been studied and a new variant of it has been found for this system. © 2006 The American Physical Society.

Abstract:

We have added an optical potential to a conventional time-averaged orbiting potential (TOP) trap to create a highly anisotropic hybrid trap for ultracold atoms. Axial confinement is provided by the optical potential; the maximum frequency currently obtainable in this direction is 2.2 kHz for rubidium. The radial confinement is independently controlled by the magnetic trap and can be a factor of 700 times smaller than in the axial direction. This large anisotropy is more than sufficient to confine condensates with ∼105 atoms in a quasi-2D (Q2D) regime, and we have verified this by measuring a change in the free expansion of the condensate; our results agree with a variational model. © 2005 IOP Publishing Ltd.

Abstract:

We theoretically investigate some of the observable properties of quasi-two-dimensional condensates. Using a variational model based on a Gaussian-parabolic trial wave function we calculate chemical potential, condensate size in time-of-flight, release energy, and collective excitation spectrum for varying trap geometries and atom numbers and find good agreement with recent published experimental results. © 2005 The American Physical Society.