Chaos signatures of current phase transition in a toroidal trap

Abstract

In this work we demonstrate how the current phase transition of atomic Bose–Einstein condensates in a toroidal trap can be controlled by applying a zero-mean oscillatory driving field. Here, the current phase transition means that the long-time averaged current undergoes a transition from a zero value to a nonzero value (or the transition from a nonzero value to a zero value). We show that due to the self-trapping effect in momentum space, the oscillatory amplitude of the current can be significantly suppressed and a nearly constant directed current can be obtained preserving the initial current values, by decreasing the driving amplitude, even when the atomic interactions are relatively small. We also reveal numerically the mean-field chaos can serve as an indicator of a quantum phase transition between the vanishing current regime and nonvanishing current regime. Our results are corroborated by an effective three-mode model, which provides an excellent account of the current dynamics of the system.

Keywords

• Self-trapping effect
• Quantum transport
• Directed current
• Mean-field chaos