![The Time Machine Factory [unspeakable, speakable] on Time Travel - TMF2024](/event/751/logo-2372865151.png){kind=logo}
Speaker
Description
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. 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 $M$ can induce a coherent dynamical evolution of a quantum system $Q$, in the presence of a conservation law, then $M$ must be non-classical. We shall explore the possibility of interpreting this temporal witness of non-classicality as the equivalent of generating entanglement in time between the single probe $Q$ before and after the evolution mediated by $M$, provided that a global quantity is conserved in the evolution. This creates a temporal parallel to the previously proposed entanglement-based witness of non-classicality, offering intriguing perspectives on locality in time and the connections between quantum correlation in space and time. Moreover, this argument supports witnesses of non-classicality relying on a single quantum probe, which can be applied to several open issues, notably in quantum gravity or quantum biology.
