Bloch oscillations of a mobile impurity in a one-dimensional Bose gas

TL;DR

This paper investigates how an impurity moves in a one-dimensional Bose gas under a constant force, revealing complex oscillatory behaviors and regimes depending on interaction strengths and external force.

Contribution

It uncovers and characterizes the rich dynamical regimes of impurity motion, including Bloch oscillations and unlimited acceleration, under various interaction and force conditions.

Findings

Impurity velocity oscillates due to emission of shock waves and solitons.

Different dynamical regimes depend on impurity-boson coupling, impurity mass, and force.

At large forces, Bloch oscillations stop and impurity accelerates indefinitely.

Abstract

We study the motion of an impurity under the action of a constant force through a one-dimensional system of weakly-interacting bosons. The interplay of the impurity-boson interaction, the boson-boson interaction, and the driving force gives rise to a rich dynamics. We focus on the influence of a finite external force. Under these far-from-equilibrium conditions, we show that in a wide range of forces, one part of the momentum transferred to the system is periodically channeled into the Bose gas through the emission of dispersive density shock waves, solitons, density waves and the creation of additional phase gradients. As a result, the impurity velocity does not increase indefinitely, but periodically oscillates in time around the drift velocity. We uncover and characterize different dynamical regimes in a wide range of the impurity-boson coupling, the impurity mass and the external force. At a sufficiently large force, the Bloch oscillations cease and the impurity exhibits an unlimited acceleration.