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Effect of noise and enhancement of nonlocality in on/off photodetection

Carmen Invernizzi·Stefano Olivares·Matteo G. A. Paris·Konrad Banaszek
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Abstract

Nonlocality of two-mode states of light is addressed by means of CHSH inequality based on displaced on/off photodetection. Effects due to non-unit quantum efficiency and nonzero dark counts are taken into account. Nonlocality of both balanced and unbalanced superpositions of few photon-number states, as well as that of multiphoton twin beams, is investigated. We find that unbalanced superpositions show larger nonlocality than balanced one when noise affects the photodetection process. De-Gaussification by means of (inconclusive) photon subtraction is shown to enhance nonlocality of twin beams in the low energy regime. We also show that when the measurement is described by a POVM, rather than a set of projectors, the maximum achievable value of the Bell parameter in the CHSH inequality is decreased, and is no longer given by the Cirel'son bound.

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Carmen Invernizzi, Stefano Olivares, Matteo G. A. Paris, Konrad Banaszek. 2005-07-06. Effect of noise and enhancement of nonlocality in on/off photodetection. https://doi.org/10.1103/physreva.72.042105

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