Vanishing geometric discord in noninertial frames

摘要

We revisit the “field entanglement in noninertial frames” scenario extensively studied in previous literature andndemonstrate that the geometric discord, a proposed measure of generalized quantum correlations, decays to zeronin the infinite acceleration limit. This is in contrast with previous research showing that the acceleration-inducedndegradation of quantum discord was not strong enough to extinguish discord in this limit. We argue that ournfinding has two opposing but noncontradicting implications. On the one hand, the usable quantum correlationsnin the large acceleration regime appear severely limited for any protocols making use of geometric discord as anfigure of merit. On the other hand, our result indicates, in corroboration with other recent work, that the geometricndiscord is not a faithful measure of quantum correlations, especially in the case of continuous-variable systems,ndue to the existence of states which have finite quantum discord but are nevertheless infinitesimally close (in thenHilbert-Schmidt norm) to a zero-discord state.