Spontaneous symmetry breaking in linearly coupled disk-shaped Bose-Einstein condensates

TL;DR

This paper investigates how tunnel coupling influences the phase transitions and symmetry breaking in a system of two parallel disk-shaped Bose-Einstein condensates with attractive interactions, revealing multiple stable states and vortex effects.

Contribution

It introduces a detailed phase diagram for coupled BECs including symmetry-breaking and collapse, with analysis of vortex presence and dynamic properties.

Findings

Identification of phase transition between symmetric, asymmetric, and collapsing states.

Modification of phase diagram due to vortex inclusion.

Dynamic properties depend strongly on the symmetry of the stationary states.

Abstract

We study effects of tunnel coupling on a pair of parallel disk-shaped Bose-Einstein condensates with the self-attractive intrinsic nonlinearity. Each condensate is trapped in a combination of in-plane and transverse harmonic-oscillator potentials. It is shown that, depending on the self-interaction strength and tunneling coupling, the ground state of the system exhibits a phase transition which links three configurations: a symmetric one with equal numbers of atoms in the coupled condensates, an asymmetric configuration with a population imbalance (a manifestation of the macroscopic quantum self-trapping), and the collapsing state. A modification of the phase diagram of the system in the presence of vortices in the disk-shaped condensates is reported too. The study of dynamics around the stationary configurations reveals properties which strongly depend on the symmetry of the configuration.