Universality and Anomalous Mean-Field Breakdown of Symmetry-Breaking Transitions in A Coupled Two-Component Condensate

TL;DR

This paper investigates symmetry-breaking transitions in a coupled two-component Bose-Einstein condensate, revealing universal scaling laws and an anomalous breakdown of mean-field predictions during dynamical processes.

Contribution

It provides a comprehensive analysis of static and dynamical symmetry-breaking transitions, highlighting the limitations of mean-field theory and the role of quantum effects in such systems.

Findings

Full quantum ground states align with mean-field predictions at static transitions.

Dynamical transitions exhibit Kibble-Zurek scaling laws.

Mean-field and quantum defect modes differ in critical points and oscillation regimes.

Abstract

We study both mean-field and full quantum dynamics of symmetry-breaking transitions (SBTs) in a coupled two-component Bose-Einstein condensate. By controlling s-wave scattering lengths and coupling strength, it is possible to stimulate SBTs between normal and spontaneously polarized ground states. In static transitions, the probability maxima of full quantum ground states correspond to the mean-field ground states. In dynamical transitions, due to the vanishing of excitation gaps, the mean-field dynamics shows universal scalings obeying Kibble-Zurek mechanism. Both mean-field and full quantum defect modes appear as damped oscillations, but they appear at different critical points and undergo different oscillation regimes. The anomalous breakdown of mean-field dynamics induced by SBTs depends on the approaching direction.