Exciton-polariton ring Josephson junction

TL;DR

This paper demonstrates a Josephson junction in an exciton-polariton ring condensate, enabling control of superfluid circulation and tunneling, with implications for integrated quantum devices and room-temperature applications.

Contribution

The authors realize and control a Josephson junction in a polariton ring condensate using optical barriers, a novel approach in this system.

Findings

Observation of superfluid-hydrodynamic and Josephson regimes

Sinusoidal tunneling current demonstrated

Theoretical explanation via free-energy landscapes

Abstract

Macroscopic coherence in quantum fluids allows the observation of interference effects in their wavefunctions, and enables applications such as superconducting quantum interference devices based on Josephson tunneling. The Josephson effect manifests in both fermionic and bosonic systems, and has been well studied in superfluid helium and atomic Bose-Einstein condensates. In exciton-polariton condensates - that offer a path to integrated semiconductor platforms - creating weak links in ring geometries has so far remained challenging. In this work, we realize a Josephson junction in a polariton ring condensate. Using optical control of the barrier, we induce net circulation around the ring and demonstrate both superfluid-hydrodynamic and the Josephson regime characterized by a sinusoidal tunneling current. Our theory in terms of the free-energy landscapes explains the appearance of these regimes using experimental values. These results show that weak links in ring condensates can be explored in optical integrated circuits and hold potential for room-temperature applications.