Title

Superfluidity in a quasi-1D atomic Bose-Einstein condensate

Date of Completion

January 2004

Keywords

Physics, Condensed Matter|Physics, Atomic

Degree

Ph.D.

Abstract

Several aspects of superfluidity in an atomic Bose-Einstein Condensate are studied in a torus-type quasi-1D model. The critical velocity of the superfluid in this quasi-1D model is found to differ from the conventional concept of the limit of velocity for frictionless flow. This result is one of the unique features of the quasi-1D system. For a generalized discrete quasi-1D model, the stability of Bloch oscillations is studied. The quasi-particle spectrum of small oscillations is analyzed, which in turn gives the phase diagram of the stable-unstable region. The results are in good agreement with a recent experimental observation. Last, we consider an experiment proposal where a phase-imprinting technique is used to generate superfluid flow with fixed momentum or a vortex in atomic BEC. Our study shows that because of backflow generated by part of the imprinting potential, phase imprinting is not an ideal tool to generate a single-momentum superflow or single vortex. ^