Phase separation and metastability in a mixture of spin-1 and spin-2 Bose-Einstein condensates

TL;DR

This paper studies the ground state and dynamics of a mixture of spin-1 and spin-2 Bose-Einstein condensates, revealing phase separation, metastability, and interface phenomena in such quantum systems.

Contribution

It provides the first detailed analysis of phase separation and metastability in mixed spinor Bose-Einstein condensates with experimentally relevant interactions.

Findings

Ground state shows phase separation between ferromagnetic and nematic states.

Partially polarized spin state appears at the interface.

Uniform mixture is metastable and can phase separate via nucleation.

Abstract

We investigate the ground state and dynamics of a mixture of spin-1 and spin-2 Bose-Einstein condensates of ${}^{87}{\rm{Rb}}$ atoms. For the experimentally measured interaction coefficients, the ground state exhibits phase separation between the spin-1 ferromagnetic state and the spin-2 nematic state. At the interface between them, a partially polarized spin state emerges. The uniformly mixed state of the spin-1 polar state and spin-2 biaxial nematic state is metastable, and the phase separation via nucleation can be triggered by a local perturbation.