Quantum correlations and dissipative blockade of polaritons in a tunable fiber cavity

TL;DR

This study investigates quantum correlations in cavity exciton-polaritons, revealing how detuning affects interactions and demonstrating a dissipative blockade mechanism that could enable strong polariton blockade.

Contribution

The paper provides experimental evidence of quantum correlations in cavity polaritons and introduces a dissipative blockade mechanism linked to biexciton broadening.

Findings

Polariton interactions strongly depend on cavity--exciton detuning.

A transition from photon antibunching to bunching occurs near the polariton resonance.

Dissipative blockade arises from large biexciton broadening, independent of laser detuning.

Abstract

Cavity exciton--polaritons are quasiparticles that form when quantum well excitons hybridize with a cavity mode. Here, we carry out photon correlation measurements under continuous wave resonant laser excitation to demonstrate quantum correlations between cavity--polaritons. Our experiments reveal an unexpectedly strong dependence of polariton interactions on cavity--exciton detuning. When the polaritons are predominantly exciton-like, we observe a transition from photon antibunching to bunching as the laser is tuned across the polariton resonance, in agreement with a simple Kerr-nonlinearity model. When the lower-branch polariton energy is tuned to induce a two-polariton Feshbach resonance with the biexciton mode, the degree of polariton antibunching becomes independent of the laser detuning: we explain our finding by invoking a dissipative blockade mechanism arising from large biexciton broadening. Our experiments demonstrate that the strong polariton blockade regime would be achieved by reducing the polariton decay rate by a factor of 10.