Anisotropic dissipation of superfluid flow in a periodically-dressed Bose-Einstein condensate

TL;DR

This paper investigates how a periodically-dressed Bose-Einstein condensate exhibits anisotropic superfluid dissipation, with a tunable dispersion relation caused by Raman coupling, and characterizes the transition from isotropic to anisotropic superfluid behavior.

Contribution

It introduces a method to control superfluid anisotropy via Raman coupling and quantifies the resulting anisotropic dissipation in a dressed Bose-Einstein condensate.

Findings

Superfluid critical velocity becomes anisotropic due to Raman coupling.

Dissipation varies with impurity flow direction, showing anisotropic behavior.

Transition from isotropic to anisotropic superfluid occurs as coupling strength increases.

Abstract

The introduction of a steady-state spatially-periodic Raman coupling between two components of an ultracold atomic gas produces a dressed-state gas with an anisotropic and tunable dispersion relation. A Bose-Einstein condensate formed in such a gas is consequently characterized by an anisotropic superfluid critical velocity. The anisotropic dissipation of superfluid flow is quantified by considering the scattering of impurities flowing through this superfluid. A gradual transition from the isotropic nature of an uncoupled Bose-Einstein condensate to the anisotropic periodically-dressed condensate is obtained as the strength of the Raman coupling is varied. These results present a clear signature for future experiemental realizations of this novel superfluid.