Van der Waals Heterostructure Polaritons with moir\'e-Induced Nonlinearity

TL;DR

This paper demonstrates strong, cooperative coupling of moiré lattice excitons with microcavity photons in van der Waals heterostructures, revealing significant nonlinearity and quantum effects at liquid-nitrogen temperatures, enabling advanced control of light-matter interactions.

Contribution

It introduces a platform integrating moiré lattice excitons with microcavity photons, showing strong nonlinearity and cooperative coupling at accessible temperatures, which was previously elusive.

Findings

Observation of strong moiré polariton coupling at liquid-nitrogen temperature

Detection of exciton blockade and suppressed dephasing effects

Evidence of quantum-confined exciton behavior in moiré lattices

Abstract

Controlling matter-light interactions with cavities is of fundamental importance in modern science and technology. It is exemplified in the strong-coupling regime, where matter-light hybrid modes form, with properties controllable via the photon component on the optical-wavelength scale. In contrast, matter excitations on the nanometer scale are harder to access. In two-dimensional van der Waals heterostructures, a tunable moir\'e lattice potential for electronic excitations may form, enabling correlated electron gases in lattice potentials. Excitons confined in moir\'e lattices have also been reported, but cooperative effects have been elusive and interactions with light have remained perturbative. Here, integrating MoSe$_{2}$-WS$_{2}$ heterobilayers in a microcavity, we establish cooperative coupling between moir\'e-lattice excitons and microcavity photons up to liquid-nitrogen temperature, thereby integrating into one platform versatile control over both matter and light. The density dependence of the moir\'e polaritons reveals strong nonlinearity due to exciton blockade, suppressed exciton energy shift, and suppressed excitation-induced dephasing, all of which are consistent with the quantum-confined nature of the moir\'e excitons. Such a moir\'e polariton system combines strong nonlinearity and microscopic-scale tuning of matter excitations with the power of cavity engineering and long range coherence of light, providing a new platform for collective phenomena from tunable arrays of quantum emitters.