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arXiv · 1804.10150

Postselection-loophole-free Bell violation with genuine time-bin entanglement

Francesco Vedovato·Costantino Agnesi·Marco Tomasin·Marco Avesani·Jan-Åke Larsson·Giuseppe Vallone·Paolo Villoresi
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Abstract

Entanglement is an invaluable resource for fundamental tests of physics and the implementation of quantum information protocols such as device-independent secure communications. In particular, time-bin entanglement is widely exploited to reach these purposes both in free-space and optical fiber propagation, due to the robustness and simplicity of its implementation. However, all existing realizations of time-bin entanglement suffer from an intrinsic postselection loophole, which undermines their usefulness. Here, we report the first experimental violation of Bell's inequality with "genuine" time-bin entanglement, free of the postselection loophole. We introduced a novel function of the interferometers at the two measurement stations, that operate as fast synchronized optical switches. This scheme allowed to obtain a postselection-loophole-free Bell violation of more than nine standard deviations. Since our scheme is fully implementable using standard fiber-based components and is compatible with modern integrated photonics, our results pave the way for the distribution of genuine time-bin entanglement over long distances.

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Francesco Vedovato, Costantino Agnesi, Marco Tomasin, Marco Avesani, Jan-Åke Larsson, Giuseppe Vallone, Paolo Villoresi. 2018-11-09. Postselection-loophole-free Bell violation with genuine time-bin entanglement. https://doi.org/10.1103/physrevlett.121.190401

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