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arXiv · 1702.00333

All entangled pure quantum states violate the bilocality inequality

Nicolas Gisin·Quanxin Mei·Armin Tavakoli·Marc-Olivier Renou·Nicolas Brunner
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Abstract

The nature of quantum correlations in networks featuring independent sources of entanglement remains poorly understood. Here, focusing on the simplest network of entanglement swapping, we start a systematic characterization of the set of quantum states leading to violation of the so-called "bilocality" inequality. First, we show that all possible pairs of entangled pure states can violate the inequality. Next, we derive a general criterion for violation for arbitrary pairs of mixed two-qubit states. Notably, this reveals a strong connection between the CHSH Bell inequality and the bilocality inequality, namely that any entangled state violating CHSH also violates the bilocality inequality. We conclude with a list of open questions.

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Nicolas Gisin, Quanxin Mei, Armin Tavakoli, Marc-Olivier Renou, Nicolas Brunner. 2017-02-01. All entangled pure quantum states violate the bilocality inequality. https://doi.org/10.1103/physreva.96.020304

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