Nonequilibrium quantum dynamics of partial symmetry breaking for ultracold bosons in an optical lattice ring trap

TL;DR

This paper investigates the nonequilibrium quantum dynamics of ultracold bosons in a ring trap, focusing on how partial symmetry breaking affects vortex behavior and system memory after a quantum quench.

Contribution

It introduces the concept of symmetry memory to identify symmetry breaking effects and links it to symmetry energy differences in low-lying excited states.

Findings

Symmetry memory effectively detects the onset of symmetry loss.

Neither current nor fidelity show critical behavior during symmetry breaking.

Symmetry energy differences correlate with symmetry memory trends.

Abstract

A vortex in a Bose-Einstein condensate on a ring undergoes quantum dynamics in response to a quantum quench in terms of partial symmetry breaking from a uniform lattice to a biperiodic one. Neither the current, a macroscopic measure, nor fidelity, a microscopic measure, exhibit critical behavior. Instead, the symmetry memory succeeds in identifying the point at which the system begins to forget its initial symmetry state. We further identify a symmetry energy difference in the low lying excited states which trends with the symmetry memory.