Superfluid density of an open dissipative condensate

TL;DR

This paper calculates the superfluid density in a non-equilibrium condensate with finite particle lifetime, showing superfluid response persists despite dissipation, and proposes a measurement method for microcavity polaritons.

Contribution

It provides a theoretical calculation of superfluid density in dissipative condensates and suggests an experimental measurement approach for microcavity polaritons.

Findings

Superfluid response exists despite absence of Landau critical velocity.

Dissipation reduces the superfluid fraction.

Proposes a measurement method for superfluid density in microcavity polaritons.

Abstract

I calculate the superfluid density of a non-equilibrium steady state condensate of particles with finite lifetime. Despite the absence of a simple Landau critical velocity, a superfluid response survives, but dissipation reduces the superfluid fraction. I also suggest an idea for how the superfluid density of an example of such a system, i.e. microcavity polaritons, might be measured.