Tunable exciton-polaritons emerging from WS2 monolayer excitons in a photonic lattice at room temperature

L Lackner,S Tongay,C Schneider,S Schröder,C Anton-Solanas,T Taniguchi,O A Egorov,B Han,H Knopf,S Höfling,M Dusel,K Watanabe,F Eilenberger

doi:10.1038/s41467-021-24925-9

Abstract

Engineering non-linear hybrid light-matter states in tailored lattices is a central research strategy for the simulation of complex Hamiltonians. Excitons in atomically thin crystals are an ideal active medium for such purposes, since they couple strongly with light and bear the potential to harness giant non-linearities and interactions while presenting a simple sample-processing and room temperature operability. We demonstrate lattice polaritons, based on an open, high-quality optical cavity, with an imprinted photonic lattice strongly coupled to excitons in a WS2 monolayer. We experimentally observe the emergence of the canonical band-structure of particles in a one-dimensional lattice at room temperature, and demonstrate frequency reconfigurability over a spectral window exceeding 85 meV, as well as the systematic variation of the nearest-neighbour coupling, reflected by a tunability in the bandwidth of the p-band polaritons by 7 meV. The technology presented in this work is a critical demonstration towards reconfigurable photonic emulators operated with non-linear photonic fluids, offering a simple experimental implementation and working at ambient conditions.

Highlights

Engineering non-linear hybrid light-matter states in tailored lattices is a central research strategy for the simulation of complex Hamiltonians
With the emergence of atomically thin crystals and the observation of giant light-matter coupling of excitons hosted in transition metal dichalcogenide (TMDC) monolayers, the research field on exciton-polaritons has experienced a paradigmatic shift on the material side: excitons in TMDC monolayers present a very large oscillator strength[12] and their large binding energies routinely facilitate the observation of exciton-polaritons from cryogenic up to room temperature[13,14,15,16]
We significantly expand the versatility of TMDC exciton-polaritons, by demonstrating their formation in a onedimensional photonic lattice imprinted in a so-called open cavity

Summary

Introduction

Exciton-polaritons in lattices have matured to a very promising and versatile platform in applied information technology[1,2,3,4] Their bosonic character enables ultra-fast condensation processes[5,6,7,8], which are already exploited in classical emulation applications[1,2], and can be harnessed in ultrafast quantum annealing architectures[9]. There is a sizeable polariton interaction[18,19] which can be engineered via injecting electrons or combining various monolayers in a van-der-Waals heterostructure[20] Those advantages, very recently, led to the first observations of polariton condensation in hybrid TMDC-III-V and in pure TMDC microcavity architectures[21,22]. The structure clearly forms the canonical gapped spectrum of Bloch-polaritons[23,24,25], and its “on-the-fly” cavity reconfigurability allows us to demonstrate the emergence of frequency tunable Bloch polaritons, with the advantage of operating at room temperature

Methods

Results

Conclusion