Observation of Superfluidity of Polaritons in Semiconductor Microcavities

TL;DR

This paper reports the experimental observation of superfluidity in exciton-polaritons within semiconductor microcavities, demonstrating quantum fluid behavior through suppression of scattering and Cerenkov wake patterns, aligning with theoretical predictions.

Contribution

First direct observation of superfluidity in polaritons in semiconductor microcavities, confirming theoretical models and expanding understanding of non-equilibrium quantum fluids.

Findings

Superfluid flow suppresses defect scattering below the speed of sound.

Cerenkov wake pattern appears when flow exceeds the speed of sound.

Experimental results match generalized Gross-Pitaevskii theory predictions.

Abstract

One of the most striking manifestations of quantum coherence in interacting boson systems is superfluidity. Exciton-polaritons in semiconductor microcavities are two-dimensional composite bosons predicted to behave as particular quantum fluids. We report the observation of superfluid motion of polaritons created by a laser in a semiconductor microcavity. Superfluidity is investigated in terms of the Landau criterion and manifests itself as the suppression of scattering from defects when the flow velocity is slower than the speed of sound in the fluid. On the other hand, a Cerenkov-like wake pattern is clearly observed when the flow velocity exceeds the speed of sound. The experimental findings are in excellent quantitative agreement with the predictions based on a generalized Gross-Pitaevskii theory, showing that polaritons in microcavities constitute a very rich system for exploring the physics of non-equilibrium quantum fluids.