Periodic quenches across the Berezinskii-Kosterlitz-Thouless phase transition

TL;DR

This paper investigates the non-equilibrium dynamics of a 2D ultracold Bose gas subjected to periodic quenches across the BKT transition, revealing diverse dynamical behaviors and potential for experimental realization.

Contribution

It introduces a numerical study of periodically driven 2D Bose gases across the BKT transition, highlighting novel non-equilibrium states and dynamical phenomena.

Findings

Identification of phase-lagged quasi adiabatic condensate formation

Resonant excitation linked to system relaxation timescales

Emergence of non-thermal, non-condensed, coherent states

Abstract

The quenched dynamics of an ultracold homogeneous atomic two-dimensional Bose gas subjected to periodic quenches across the Berezinskii-Kosterlitz-Thouless (BKT) phase transition are discussed. Specifically, we address the effect of periodic cycling of the effective atomic interaction strength between a thermal disordered state above, and a highly ordered state below the critical BKT interaction strength, by means of numerical simulations of the stochastic projected Gross-Pitaevskii equation. Probing the emerging dynamics as a function of the frequency of sinusoidal driving from low to high frequencies reveals diverse dynamical features, including phase-lagged quasi adiabatic reversible condensate formation, resonant excitation consistent with an intrinsic system relaxation timescale, and gradual establishment of dynamically-recurring or time-averaged non-equilibrium states with enhanced coherence which are neither condensed, nor thermal. Our study paves the way for experimental observation of such driven non-equilibrium ultracold superfluid states.