Observation of bosonic condensation in a hybrid monolayer MoSe2-GaAs microcavity

TL;DR

This paper reports the first observation of bosonic condensation in a hybrid monolayer MoSe2-GaAs microcavity, demonstrating exciton-polariton condensation with spin-polarization, opening avenues for valleytronic devices and topological studies.

Contribution

It introduces the experimental realization of polariton condensation in a monolayer MoSe2 integrated with a solid-state resonator, a novel platform for studying quantum fluids in 2D materials.

Findings

Observation of polariton condensation at low excitation powers

Detection of density-dependent blueshift and linewidth collapse

Significant spin-polarization in the condensate

Abstract

Condensation of bosons into a macroscopic quantum state belongs to the most intriguing phenomena in nature. It was first realized in quantum gases of ultra-cold atoms, but more recently became accessible in open-dissipative, exciton-based solid-state systems at elevated temperatures. Semiconducting monolayer crystals have emerged as a new platform for studies of strongly bound excitons in ultimately thin materials. Here, we demonstrate the formation of a bosonic condensate driven by excitons hosted in an atomically thin layer of MoSe2, strongly coupled to light in a solid-state resonator. The structure is operated in the regime of collective strong coupling, giving rise to hybrid exciton-polariton modes composed of a Tamm-plasmon resonance, GaAs quantum well excitons and two-dimensional excitons confined in a monolayer of MoSe2. Polariton condensation in a monolayer crystal manifests by a superlinear increase of emission intensity from the hybrid polariton mode at injection powers as low as 4.8 pJ/pulse, as well as its density-dependent blueshift and a dramatic collapse of the emission linewidth as a hallmark of temporal coherence. Importantly, we observe a significant spin-polarization in the injected polariton condensate, a fingerprint of the core property of monolayer excitons subject to spin-valley locking. The observed effects clearly underpin the perspective of building novel highly non-linear valleytronic devices based on light-matter fluids, coherent bosonic light sources based on atomically thin materials, and paves the way towards studying materials with unconventional topological properties in the framework of bosonic condensation.