Quantum coherence of a long-lifetime exciton-polariton condensate

TL;DR

This paper demonstrates how to enhance quantum coherence in long-lifetime exciton-polariton condensates by spatially separating the condensate from the reservoir, with implications for quantum device integration.

Contribution

It introduces a method to optimize quantum coherence in polariton condensates by minimizing reservoir interactions, combining experimental data with a thermal state model.

Findings

Quantum coherence increases above the condensation threshold.

Spatial separation enhances maximum quantum coherence.

Reservoir interaction minimization improves coherence quality.

Abstract

In recent years, quantum information science has made significant progress, leading to a multitude of quantum protocols for the most diverse applications. States carrying resources such as quantum coherence are a key component for these protocols. In this study, we optimize the quantum coherence of a nonresonantly excited exciton-polariton condensate of long living polaritons by minimizing the condensate's interaction with the surrounding reservoir of excitons and free carriers. By combining experimental phase space data with a displaced thermal state model, we observe how quantum coherence builds up as the system is driven above the condensation threshold. Our findings demonstrate that a spatial separation between the condensate and the reservoir enhances the state's maximum quantum coherence directly beyond the threshold. These insights pave the way for integrating polariton systems into hybrid quantum devices and advancing applications in quantum technologies.