Non-classicality tests and entanglement witnesses for macroscopic mechanical superposition states

TL;DR

This paper proposes measurement protocols for testing non-classicality and verifying entangled superposition states in macroscopic mechanical systems, enabling experimental validation of quantum phenomena at large scales.

Contribution

It introduces generalized techniques for detecting non-classical states and entanglement in macroscopic resonators using qubit-based measurements, applicable to current experimental setups.

Findings

Protocols enable detection of non-classical mechanical states

Methods allow preparation and verification of entangled resonator states

Applicable to various qubit-resonator systems in experiments

Abstract

We describe a set of measurement protocols for performing non-classicality tests and the verification of entangled superposition states of macroscopic continuous variable systems, such as nanomechanical resonators. Following earlier works, we first consider a setup where a two-level system is used to indirectly probe the motion of the mechanical system via Ramsey measurements and discuss the application of this methods for detecting non-classical mechanical states. We then show that the generalization of this techniques to multiple resonator modes allows the conditioned preparation and the detection of entangled mechanical superposition states. The proposed measurement protocols can be implemented in various qubit-resonator systems that are currently under experimental investigation and find applications in future tests of quantum mechanics at a macroscopic scale.