High-visibility time-bin entanglement for testing chained Bell inequalities

Tomasin, Marco; Mantoan, Elia; Jogenfors, Jonathan; Vallone, Giuseppe; Larsson, Jan‐Åke; Villoresi, Paolo

doi:10.1103/physreva.95.032107

Cited by 8 publications

(9 citation statements)

References 22 publications

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“…It is easily computed that leapfrog emission would break the Franson limit, but in the light of the Franson configuration’s loophole 63 , the new challenge is to turn to stricter conditions of Bell violations such as Chained Bell’s inequalities. While this has been recently demonstrated 64 , the tunable statistics from the Mollow triplet and its windows of strong correlations make it a promising platform to further test and advance this line of research. Finally, the combinatoric aspects that quickly make such simple problems numerically forbidding also suggest that a two-level system could be used in the laboratory for tests of quantum supremacy directly from photon detections, without a complex system of beam splitters intervening to bring in the quantum complexity 65 , 66 .…”

Section: Discussionmentioning

confidence: 99%

Frequency-resolved Monte Carlo

Carreño

Valle

Laussy

2018

Sci Rep

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We adapt the Quantum Monte Carlo method to the cascaded formalism of quantum optics, allowing us to simulate the emission of photons of known energy. Statistical processing of the photon clicks thus collected agrees with the theory of frequency-resolved photon correlations, extending the range of applications based on correlations of photons of prescribed energy, in particular those of a photon-counting character. We apply the technique to autocorrelations of photon streams from a two-level system under coherent and incoherent pumping, including the Mollow triplet regime where we demonstrate the direct manifestation of leapfrog processes in producing an increased rate of two-photon emission events.

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Section: Discussionmentioning

confidence: 99%

Frequency-resolved Monte Carlo

Carreño

Valle

Laussy

2018

Sci Rep

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“…An important application is Quantum Key Distribution (QKD) based on the Franson interferometer [5] where it is known [6][7][8] that the CHSH inequality is insufficient as a security test. If the switch to the full PBC is made, full security can be re-established [7,9].…”

Section: Introductionmentioning

confidence: 99%

“…Specifically, such an experiment requires a very high visibility, and until recently it was believed [7] that these requirements were too impractical to achieve. Recent works [9], however, showed it possible to meet these requirements by reaching a full violation of the PBC inequality for N = 3, 4, and 5 with visibility in excess of 94.63 %.…”

Section: Introductionmentioning

confidence: 99%

Tight bounds for the Pearle-Braunstein-Caves chained inequality without the fair-coincidence assumption

Jogenfors

Larsson

2017

Phys. Rev. A

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In any Bell test, loopholes can cause issues in the interpretation of the results, since an apparent violation of the inequality may not correspond to a violation of local realism. An important example is the coincidence-time loophole that arises when detector settings might influence the time when detection will occur. This effect can be observed in many experiments where measurement outcomes are to be compared between remote stations because the interpretation of an ostensible Bell violation strongly depends on the method used to decide coincidence. The coincidence-time loophole has previously been studied for the Clauser-Horne-Shimony-Holt and Clauser-Horne inequalities, but recent experiments have shown the need for a generalization. Here, we study the generalized "chained" inequality by Pearle, Braunstein, and Caves (PBC) with N 2 settings per observer. This inequality has applications in, for instance, quantum key distribution where it has been used to reestablish security. In this paper we give the minimum coincidence probability for the PBC inequality for all N 2 and show that this bound is tight for a violation free of the fair-coincidence assumption. Thus, if an experiment has a coincidence probability exceeding the critical value derived here, the coincidence-time loophole is eliminated.

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“…Another possible way to overcome it requires to violate the "chained" Bellinequalities [48], but the needed visibility ( 0.94 [25]) is considerably higher than the one of the Bell-CHSH inequality ( 0.71). Even if such a high visibility is achievable [49], our scheme strongly relaxes this requirement, since the Bell-CHSH inequality is directly applicable.…”

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confidence: 99%

Postselection-Loophole-Free Bell Violation with Genuine Time-Bin Entanglement

et al. 2018

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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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High-visibility time-bin entanglement for testing chained Bell inequalities

Cited by 8 publications

References 22 publications

Frequency-resolved Monte Carlo

Frequency-resolved Monte Carlo

Tight bounds for the Pearle-Braunstein-Caves chained inequality without the fair-coincidence assumption

Postselection-Loophole-Free Bell Violation with Genuine Time-Bin Entanglement

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