Witnessing the nonclassical nature of gravity in the presence of unknown interactions
Hadrien Chevalier, A. J. Paige, M. S. Kim
Abstract
General relativity is a classical field theory and therefore does not predict gravitationally induced entanglement. As such, recent proposals have focused on seeking an empirical demonstration of this feature. We introduce improvements to a spin witness protocol that reduce the highly challenging experimental requirements. After rigorously assessing approximations from the original proposal [S. Bose et al., Phys. Rev. Lett. 119, 240401 (2017)], we focus on entanglement witnessing. We propose a witness which greatly reduces the required interaction time, thereby making the experiment feasible for higher decoherence rates, and we show how statistical analysis can separate the gravitational contribution from other possibly dominant and ill-known interactions. We point out a potential loophole and show how it can be closed using state tomography.