Witnessing non-classicality beyond quantum theory

Author: Chiara Marletto, Vlatko Vedral
Date: 17 March 2020
Affiliations: Clarendon Laboratory, Department of Physics, University of Oxford // Centre for Quantum Technologies, National University of Singapore // Department of Physics, National University of Singapore // ISI Foundation, Turin
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We propose a general argument to show that if a physical system can mediate locally the generation of entanglement between two quantum systems, then it itself must be non-classical. Remarkably, we do not assume any classical or quantum formalism to describe the mediating physical system: our result follows from general information-theoretic principles, drawn from the recently proposed constructor theory of information. This argument provides the indispensable theoretical basis for recently proposed tests of non-classicality in gravity, based on witnessing gravitationally-induced entanglement in quantum probes.