Electron entanglement near a superconductor and bell inequalities |
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Authors: | Thierry Martin Chantal Lovarco |
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Institution: | (1) Centre de Physique Théorique et Université de la Mediterranée, Case 907, 13288 Marseille, France |
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Abstract: | Near the interface between a normal metal and a superconductor, Cooper pairs penetrate into the normal side, giving rise to
the proximity effect. The two electrons of these pairs have entangled spin and orbital degrees of freedom. Nonlocal features
of quantum mechanics can be probed by separating these two electrons. This is achieved with a fork geometry with two normal
leads containing either spin- or energy-selective filters. A signature of entanglement can be detected by measuring the positive
noise cross-correlations in this fork. In the case of energy filters, Bell-inequality checks constitute a definite probe of
entanglement. We formulate Bell-type inequalities in terms of current-current cross-correlations associated with contacts
with varying magnetization orientations. We find maximal violation (as in photons) when a superconductor is the particle source. |
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Keywords: | Entanglement Andreev reflection mesoscopic physics |
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