Quantum nature of Gaussian discord : experimental evidence and role of system-environment correlations
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We provide experimental evidence of quantum features in bipartite states classified as entirely classical according to a conventional criterion based on the Glauber P function but possessing nonzero Gaussian quantum discord. Their quantum nature is experimentally revealed by acting locally on one part of the discordant state. We experimentally verify and investigate the effect of discord increase under the action of local loss and link it to the entanglement with the environment. Adding an environmental system purifying the state, we unveil the flow of quantum correlations within a global pure system using the Koashi-Winter inequality. For a discordant state generated by splitting a state in which the initial squeezing is destroyed by random displacements, we demonstrate the recovery of entanglement highlighting the role of system-environment correlations.
Chille , V , Quinn , N , Peuntinger , C , Croal , C , Mišta , L , Marquardt , C , Leuchs , G & Korolkova , N 2015 , ' Quantum nature of Gaussian discord : experimental evidence and role of system-environment correlations ' Physical Review. A, Atomic, molecular, and optical physics , vol 91 , no. 5 , 050301(R) . DOI: 10.1103/PhysRevA.91.050301
Physical Review. A, Atomic, molecular, and optical physics
© 2015 American Physical Society. Archived in accordance with the publisher's reuse policy. Originally published by Physical Review A, 91(5), here: http://journals.aps.org/pra/abstract/10.1103/PhysRevA.91.050301
L.M. acknowledges Project No. P205/12/0694 of Czech Science Foundation (GACR). N.K. is grateful for the support provided by the A. von Humboldt Foundation. N.Q. and N.K. acknowledge the support from the Scottish Universities Physics Alliance (SUPA) and the Engineering and Physical Sciences Research Council (EPSRC). The project was supported within the framework of the BMBF grant “QuORep” and in the framework of the International Max Planck Partnership (IMPP) with Scottish Universities.
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