Temperature driven false vacuum decay in coherently coupled Bose superfluids

TL;DR

This paper investigates how temperature influences false vacuum decay in a coherently coupled Bose superfluid, demonstrating exponential decay rate dependence on temperature and exploring phase dynamics using the stochastic Gross-Pitaevskii equation.

Contribution

It introduces the use of the SGPE to study temperature-driven false vacuum decay and phase dynamics in a two-dimensional Bose-Bose mixture, extending previous one-dimensional experiments.

Findings

Decay rates depend exponentially on temperature.

Phase dynamics become significant during decay.

SGPE effectively models coupled magnetization and phase behavior.

Abstract

The relaxation of a quantum field from a metastable state (false vacuum) to a stable one (true vacuum), also known as false vacuum decay, is a fundamental problem in quantum field theory and cosmology. We study this phenomenon using a two-dimensional interacting and coherently coupled Bose-Bose mixture, a platform that has already been employed experimentally to investigate false vacuum decay in one dimension. In such a mixture, it is possible to define an effective magnetization that acts as a quantum field variable. Using the Stochastic Gross-Pitaevskii equation (SGPE), we prepare thermal equilibrium states in the false vacuum and extract decay rates from the magnetization dynamics. The decay rates show an exponential dependence on temperature, in line with the thermal theory of instantons. Since the SGPE is based on complex scalar fields, it also allows us to explore the behavior of the phase, which turns out to become dynamic during decay. Our results confirm the SGPE as an effective tool for studying coupled magnetization and phase dynamics and the associated instanton physics in ultracold quantum gases.