Generating nonequilibrium stationary state from ground state condensate through an almost-adiabatic cycle

TL;DR

This paper demonstrates how a weakly interacting Bose condensate in a quasi-1D trap can be transformed into a nonequilibrium stationary state with population inversion through an almost-adiabatic cycle involving an impurity quench, robust against cycle details.

Contribution

It introduces a method to generate nonequilibrium stationary states from ground states using a cyclic impurity quench, highlighting robustness and conditions for population inversion.

Findings

Successful conversion to nonequilibrium states with population inversion.

Robustness of the process against cycle details.

Failure of inversion under strong interactions.

Abstract

It is shown that the ground state of weakly interacting Bose particles in a quasi one-dimensional box trap can be converted into an excited stationary state by an adiabatic cyclic operation that involves a quench of interaction strength: A sharp impurity potential is applied and its strength is varied during the cycle, which induces a nonequilibrium stationary state exhibiting the inversion of population. This process is robust in the sense that the resultant stationary state is almost independent of the details of the cycle, such as the position of the impurity as long as the cycle is far enough from critical regions. The case of the failure of the population inversion due to the strong interparticle interactions is also examined.