Witnessing Opto-Mechanical Entanglement with Photon-Counting

TL;DR

This paper proposes a photon-counting based witness to detect opto-mechanical entanglement without efficiency constraints, enabling Bell tests in current nanobeam resonator experiments for quantum information applications.

Contribution

It introduces a new entanglement witness that does not depend on detection efficiency and can be applied with minimal system knowledge, facilitating experimental verification of opto-mechanical entanglement.

Findings

The witness can detect entanglement despite noise and losses.

Feasibility analysis shows applicability in current nanobeam resonator setups.

The method does not require detailed system modeling.

Abstract

The ability to coherently control mechanical systems with optical fields has made great strides over the past decade, and now includes the use of photon counting techniques to detect the non-classical nature of mechanical states. These techniques may soon be used to perform an opto-mechanical Bell test, hence highlighting the potential of cavity opto-mechanics for device-independent quantum information processing. Here, we propose a witness which reveals opto-mechanical entanglement without any constraint on the global detection efficiencies in a setup allowing one to test a Bell inequality. While our witness relies on a well-defined description and correct experimental calibration of the measurements, it does not need a detailed knowledge of the functioning of the opto-mechanical system. A feasibility study including dominant sources of noise and loss shows that it can readily be used to reveal opto-mechanical entanglement in present-day experiments with photonic crystal nanobeam resonators.