Self-Induced Valley Bosonic Stimulation of Exciton-Polaritons in a Monolayer Semiconductor

TL;DR

This paper demonstrates self-induced valley bosonic stimulation of exciton-polaritons in a WS2 monolayer, revealing nonlinear effects and paving the way for spin-based quantum phenomena in 2D materials.

Contribution

It reports the first observation of valley-dependent bosonic stimulation of exciton-polaritons via spin-valley locking in a monolayer TMD microcavity.

Findings

Observation of nonlinear self-amplification of polariton emission.

Efficient population of ground state polaritons in specific valleys.

Potential for exploring spin ordering and phase transitions in TMD polariton BECs.

Abstract

The newly discovered valley degree of freedom in atomically thin two-dimensional transition metal dichalcogenides (TMD) offers a promising platform to explore rich nonlinear physics, such as spinor Bose-Einstein condensate (BEC) and novel valleytronics applications. However, the critical nonlinear effect, such as valley polariton bosonic stimulation, has long remained an unresolved challenge due to the generation of limited polariton ground state densities necessary to induce the stimulated scattering of polaritons in specific valleys. Here, we report the self-induced valley bosonic stimulation of exciton-polaritons via spin-valley locking in a WS2 monolayer microcavity. This is achieved by the resonant injection of valley polaritons at specific energy and wavevector, which allows spin-polarized polaritons to efficiently populate their ground state and induce a valley-dependent bosonic stimulation. As a result, we observe the nonlinear self-amplification of polariton emission from the valley-dependent ground state. Our finding paves the way for the investigation of spin ordering and phase transitions in TMD polariton BEC, offering a promising route for the realization of polariton spin lattices in moir\'e polariton systems and spin-lasers.