On Berezinskii-Kosterlitz-Thouless Phase Transition in Quasi-One Dimensional Bose-Einstein Condensate

TL;DR

This paper demonstrates that under certain conditions, a quasi-one dimensional Bose-Einstein condensate can undergo a Berezinskii-Kosterlitz-Thouless phase transition, with dark solitons playing a role similar to vortices in 2D.

Contribution

It introduces the possibility of BKT transition in quasi-1D BECs and identifies dark solitons as the key excitations involved in this transition.

Findings

Critical temperature in nano Kelvin range for the transition.

Disordered phase shows loss of phase coherence.

Ordered phase exhibits phase coherence detectable experimentally.

Abstract

We show that quasi-one dimensional Bose-Einstein condensate under suitable conditions can exhibit a Berezinskii-Kosterlitz-Thouless phase transition. The role played by quantized vortices in two dimensional case, is played in this case by dark solitons. We find that the critical temperature for this transition lies in nano Kelvin range and below, for a wide range of experimentally accessible parameters. It is seen that the high temperature (disordered) phase differs from low temperature (ordered) phase in terms of phase coherence, which can be used as an experimental signature for observing this transition.