Gaussian trajectory description of fragmentation in an isolated spinor condensate

TL;DR

This paper introduces a Gaussian trajectory method with dissipation to model the formation of fragmentation in spinor Bose gases, capturing dynamics beyond traditional Gaussian approximations.

Contribution

It develops a dissipative Gaussian variational approach to simulate fragmentation dynamics in spinor condensates, accounting for entanglement effects.

Findings

The method accurately reproduces the formation of fragmented condensates.

Optimal dissipation levels can prevent fragmentation in single experimental realizations.

The approach extends Gaussian variational techniques to include dissipation effects.

Abstract

Spin-1 Bose gases quenched to spin degeneracy exhibit fragmentation: the appearance of a condensate in more than one single-particle state. Due to its highly entangled nature, the dynamics leading to this collective state are beyond the scope of a Gaussian variational approximation of the many-body wave function. Here, we improve the performance of the Gaussian variational Ansatz by considering dissipation into a fictitious environment, effectively suppressing entanglement within individual quantum trajectories at the expense of introducing a classical mixture of states. We find that this quantum trajectory approach captures the dynamical formation of a fragmented condensate, and analyze how much dissipation should be added to the experiment in order to keep a single realization in a non-fragmented state.