Witnessing quantumness of a system by observing only its classical features
Abstract
Witnessing non-classicality in the gravitational field has been claimed to be practically impossible. This constitutes a deep problem, which has even lead some researchers to question whether gravity should be quantised, due to the weakness of quantum effects. To counteract these claims, we propose a thought experiment that witnesses non-classicality of a physical system by probing it with a qubit. Remarkably, this experiment does not require any quantum control of the system, involving only measuring a single classical observable on that system. In addition, our scheme does not even assume any specific dynamics. That non-classicality of a system can be established indirectly, by coupling it to a qubit, opens up the possibility that quantum gravitational effects could in fact be witnessed in the lab.
Cite
@article{arxiv.1704.00120,
title = {Witnessing quantumness of a system by observing only its classical features},
author = {Chiara Marletto and Vlatko Vedral},
journal= {arXiv preprint arXiv:1704.00120},
year = {2017}
}