Dynamical effects of exchange symmetry breaking in mixtures of interacting bosons

TL;DR

This paper investigates how exchange symmetry breaking affects the dynamics of mixed Bose-Einstein condensates in double-well potentials, revealing tunable oscillation behaviors and effective single-species descriptions in mean-field and many-body frameworks.

Contribution

It introduces an effective single-species model for mixed bosonic systems with exchange symmetry breaking, applicable to Bose-Hubbard and mean-field systems, enhancing understanding of multicomponent Bose gases.

Findings

Oscillation behavior can be tuned by populating the second species.

Single-species description approximates full counting statistics well.

Method extends to Bose-Hubbard systems and classical mean-field limits.

Abstract

In a double-well potential, a Bose-Einstein condensate exhibits Josephson oscillations or self-trapping, depending on its initial preparation and on the ratio of inter-particle interaction to inter-well tunneling. Here, we elucidate the role of the exchange symmetry for the dynamics with a mixture of two distinguishable species with identical physical properties, i.e. which are governed by an isospecific interaction and external potential. In the mean-field limit, the spatial population imbalance of the mixture can be described by the dynamics of a single species in an effective potential with modified properties or, equivalently, with an effective total particle number. The oscillation behavior can be tuned by populating the second species while maintaining the spatial population imbalance and all other parameters constant. In the corresponding many-body approach, the single-species description approximates the full counting statistics well also outside the realm of spin-coherent states. The method is extended to general Bose-Hubbard systems and to their classical mean-field limits, which suggests an effective single-species description of multicomponent Bose gases with weakly an-isospecific interactions.