Superflow of resonantly driven polaritons against a defect

TL;DR

This paper non-perturbatively analyzes resonantly driven polariton fluids, revealing that they always experience residual drag when flowing through a defect, challenging the traditional superfluidity criteria based on the Landau criterion.

Contribution

It demonstrates that even at high densities, polariton fluids exhibit residual drag due to finite lifetime effects, showing a smooth crossover rather than a sharp superfluid transition.

Findings

Residual drag persists at high densities due to finite polariton lifetime.

The zero-drag limit is only achievable in perfect microcavities.

Crossover behavior replaces sharp superfluid threshold.

Abstract

In the linear response approximation, coherently driven microcavity polaritons in the pump-only configuration are expected to satisfy the Landau criterion for superfluidity at either strong enough pump powers or small flow velocities. Here, we solve non-perturbatively the time dependent Gross-Pitaevskii equation describing the resonantly-driven polariton system. We show that, even in the limit of asymptotically large densities, where in linear response approximation the system satisfies the Landau criterion, the fluid always experiences a residual drag force when flowing through the defect. We illustrate the result in terms of the polariton lifetime being finite, finding that the equilibrium limit of zero drag can only be recovered in the case of perfect microcavities. In general, both the drag force exerted by the defect on the fluid, as well as the height of Cerenkov radiation, and the percentage of particles scattered by the defect, show a smooth crossover rather than a sharp threshold-like behaviour typical of superfluids which obey the Landau criterion.