Stochastic Projected Gross-Pitaevskii equation for spinor and multi-component condensates

TL;DR

This paper derives a stochastic Gross-Pitaevskii equation for multi-component Bose gases, capturing dissipative dynamics and phase transitions, with applications to spinor condensates and two-component mixtures.

Contribution

It introduces a new classical-field theory for multi-component Bose gases, including novel dissipative processes involving particle interchange between coherent and incoherent regions.

Findings

Derived analytical dissipation rates for systems near equilibrium.

Applied formalism to two-component mixtures and spin-1 condensates.

Identified new dissipative processes involving particle interchange.

Abstract

A stochastic Gross-Pitaevskii equation is derived for partially condensed Bose gas systems subject to binary contact interactions. The theory we present provides a classical-field theory suitable for describing dissipative dynamics and phase transitions of spinor and multi-component Bose gas systems comprised of an arbitrary number of distinct interacting Bose fields. A new class of dissipative processes involving distinguishable particle interchange between coherent and incoherent regions of phase-space is identified. The formalism and its implications are illustrated for two-component mixtures and spin-1 Bose-Einstein condensates. For systems comprised of atoms of equal mass, with thermal reservoirs that are close to equilibrium, the dissipation rates of the theory are reduced to analytical expressions that may be readily evaluated. The unified treatment of binary contact interactions presented here provides a theory with broad relevance for quasi-equilibrium and far-from-equilibrium Bose-Einstein condensates.