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arXiv:2603.15747

Ising criticality can drive vortex deconfinement in a spin-orbit coupled Bose gas

Stuart Thomas, David M. Long, Jay Deep Sau

Published Mar 16, 2026• 0 citations
arXivHTMLPDF

Abstract

Spin-orbit coupling in Bose gases is known to lead to an Ising-symmetry-broken phase where the bosons condense at one of two nonzero momenta. In two dimensions, the finite momentum of the order parameter allows vortex-antivortex pairs that are typically bound in the superfluid phase to freely separate along Ising domain walls. This non-trivial interaction between the superfluid and the Ising order suggests that the critical fluctuations near an Ising transition could drive a Berezinskii-Kosterlitz-Thouless transition of the superfluid. We present numerical evidence of this phenomenon using a Monte Carlo simulation that shows the disappearance of superfluid stiffness near an Ising transition. Additionally, we find numerical evidence that the Ising phase transition becomes first order and we justify this claim with a variational approximation.

DOI
10.48550/arxiv.2603.15747

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We determine the finite-temperature phase diagram of two-dimensional bosons with two hyperfine (pseudospin) states coupled via a Rashba-Dresselhaus spin-orbit interaction using classical field Monte Carlo calculations. For anisotropic spin-orbit coupling, we find a transition to a Berezinskii-Kosterlitz-Thouless superfluid phase with quasi-long-range order. We show that the spin order of the quasicondensate is driven by the anisotropy of the interparticle interaction, favoring either a homogeneous plane-wave state or stripe phase with broken translational symmetry. Both phases show characteristic behavior in the algebraically decaying spin-density correlation function. For a fully isotropic interparticle interaction, our calculations indicate a fractionalized quasicondensate where the mean-field degeneracy of the plane-wave and stripe phase remains robust against critical fluctuations. In the case of fully isotropic spin-orbit coupling, the circular degeneracy of the single-particle ground state destroys the algebraic ordered phase in the thermodynamic limit, but a crossover remains for finite-size systems.