Revealing non-classicality of inaccessible objects

TL;DR

This paper introduces a robust, experimentally friendly scheme to infer the non-classicality of inaccessible objects using entanglement dynamics of probes, applicable to systems like optomechanical setups and potentially to gravity.

Contribution

The authors propose a novel method to assess non-classicality of inaccessible objects via entanglement monitoring, without assumptions on initial states or system details.

Findings

Successfully applied to optomechanical systems to detect non-classicality.

Allows inference of system-environment correlations in open systems.

Potential application in probing the non-classical nature of gravity.

Abstract

Some physical objects are hardly accessible to direct experimentation. It is then desirable to infer their properties based solely on the interactions they have with systems over which we have control. In this spirit, here we introduce schemes for assessing the non-classicality of the inaccessible objects as characterised by quantum discord. We consider two probes individually interacting with the inaccessible object, but not with each other. The schemes are based on monitoring entanglement dynamics between the probes. Our method is robust and experimentally friendly as it allows the probes and the object to be open systems, makes no assumptions about the initial state, dimensionality of involved Hilbert spaces and details of the probe-object Hamiltonian. We apply our scheme to a membrane-in-the-middle optomechanical system, to detect system-environment correlations in open system dynamics as well as non-classicality of the environment, and we foresee potential benefits for the inference of the non-classical nature of gravity.