Spin-orbit coupled mean-field Bose gas at finite temperature

TL;DR

This paper studies how spin-orbit coupling affects the phase diagram and stability of Bose-Einstein condensates at finite temperature, revealing that spin-orbit interactions stabilize uniform condensates and alter phase transition properties.

Contribution

It provides a detailed analysis of the finite-temperature phase diagram of spin-orbit coupled Bose gases, highlighting the stabilizing effect of spin-orbit coupling on uniform BEC phases and the impact on phase transition characteristics.

Findings

Uniform BEC phases are stable at finite temperature with spin-orbit coupling.

Spin-orbit coupling stabilizes the zero-momentum condensate across dimensions.

Phase boundaries shift significantly with variations in spin-orbit coupling strength.

Abstract

We consider the spin-orbit coupled Bose gas with repulsive mean-field interparticle interactions. We analyze the phase diagram of the system varying the temperature $T>0$, the chemical potentials, as well as interparticle and spin-orbit interaction couplings. Our results indicate that, for Rashba- and Weyl-type spin-orbit couplings, condensates featuring ordering wavevector $\vec{Q}\neq \vec{0}$ are fragile with respect to thermal fluctuations and, at $T>0$, the only stable thermodynamic phases involving the Bose-Einstein condensate (BEC) are those of uniform type with $\vec{Q}=\vec{0}$. On the other hand, presence of the spin-orbit coupling stabilizes the $\vec{Q}=\vec{0}$ BEC state at any dimensionality $d>1$ and modifies either the order or the universality class of the corresponding phase transition. We emphasize the singular nature of the limit of vanishing spin-orbit interaction coupling $v$, sizable shifts of the phase boundaries upon varying $v$, as well as the role of the relative magnitudes of the interparticle interaction couplings for the character of the condensation transition.