Temporal witnesses of non-classicality and conservation laws

Author: Giuseppe Di Pietra, Chiara Marletto
Date: 3 May 2022
Affiliations: Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, Italy // Clarendon Laboratory, University of Oxford, UK // Centre for Quantum Technologies, National University of Singapore, Singapore
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A general entanglement-based witness of non-classicality has recently been proposed, which can be applied to testing quantum effects in gravity. This witness is based on generating entanglement between two quantum probes via a mediator. In this paper we provide a “temporal” variant of this witness, using a single quantum probe to assess the non-classicality of the mediator. Within the formalism of quantum theory, we show that if a system M is capable of inducing a coherent dynamical evolution of a quantum system Q, in the presence of a conservation law, then M must be non-classical. This argument supports witnesses of non-classicality relying on a single quantum probe, which can be applied to a number of open issues, notably in quantum gravity or quantum biology.