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arXiv · 1310.5640

Entanglement witnessing and quantum cryptography with non-ideal ferromagnetic detectors

Waldemar Kłobus·Andrzej Grudka·Andreas Baumgartner·Damian Tomaszewski·Christian Schönenberger·Jan Martinek
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Abstract

We investigate theoretically the use of non-ideal ferromagnetic contacts as a mean to detect quantum entanglement of electron spins in transport experiments. We use a designated entanglement witness and find a minimal spin polarization of $η> 1/\sqrt{3} \approx 58 %$ required to demonstrate spin entanglement. This is significantly less stringent than the ubiquitous tests of Bell's inequality with $η> 1/\sqrt[4]{2}\approx 84%$. In addition, we discuss the impact of decoherence and noise on entanglement detection and apply the presented framework to a simple quantum cryptography protocol. Our results are directly applicable to a large variety of experiments.

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Waldemar Kłobus, Andrzej Grudka, Andreas Baumgartner, Damian Tomaszewski, Christian Schönenberger, Jan Martinek. 2014-03-05. Entanglement witnessing and quantum cryptography with non-ideal ferromagnetic detectors. https://doi.org/10.1103/physrevb.89.125404

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