Optomechanical Bell test

TL;DR

This paper demonstrates the violation of Bell inequalities using photon pairs generated in an optomechanical system, showcasing non-local correlations between light and mechanical states, and paving the way for device-independent quantum optomechanics.

Contribution

It introduces a method to detect non-local light-mechanical correlations via Bell inequality violation in an optomechanical setup, enabling device-independent quantum certification.

Findings

Photon-phonon pairs can violate Bell inequalities.

Non-local correlations between light and mechanical states are detectable.

Method enables device-independent quantum optomechanics.

Abstract

Photons of a laser beam driving the upper motional sideband of an optomechanical cavity can decay into photon-phonon pairs by means of an optomechanical parametric process. The phononic state can subsequently be mapped to a photonic state by exciting the lower sideband, hence creating photon-photon pairs out of an optomechanical system. We here demonstrate that these pairs can violate a Bell inequality when they are measured with photon counting techniques preceded by small displacement operations in the phase space. Our results show how to detect non-local light-mechanical correlations and open the way for device-independent quantum optomechanics where non-classical light-mechanical correlations can be certified without assumptions on the state structure or on the measurement devices.