Traveling supersolid stripe patterns in spin-orbit-coupled Bose-Einstein condensates

TL;DR

This paper investigates traveling supersolid stripe patterns in spin-orbit-coupled Bose-Einstein condensates, revealing their spin polarization, stability conditions, and transition to uniform phases through analysis of their excitation spectra.

Contribution

It introduces the concept of moving supersolid stripes with spin polarization and analyzes their stability and transition mechanisms in spin-orbit-coupled Bose gases.

Findings

Traveling stripes are spin-polarized and their contrast decreases with population imbalance.

Stripe melting occurs at high imbalance, transitioning to the plane-wave phase.

Instabilities in the excitation spectrum lead to phase transitions and pattern melting.

Abstract

We consider a traveling supersolid stripe pattern in a spin-orbit-coupled Bose gas. This configuration is associated with an unequal population of the two single-particle energy minima, giving rise to a chemical potential difference that sets the fringe velocity. Unlike stationary stripes, the moving pattern is spin-polarized, with decreasing contrast as the population imbalance increases, eventually leading to stripe melting and transition to the uniform plane-wave phase. The Bogoliubov spectrum of the moving stripes exhibits asymmetry under inversion of the excitation quasimomentum. At high population imbalance, we identify energetic and dynamical instabilities in the spin-phonon mode which transforms to the roton mode of the plane-wave phase as the stripe structure vanishes.