How post-selection affects device-independent claims under the fair sampling assumption

Orsucci, Davide; Bancal, Jean-Daniel; Sangouard, Nicolas; Sekatski, Pavel

doi:10.22331/q-2020-03-02-238

Cited by 13 publications

(23 citation statements)

References 58 publications

(102 reference statements)

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“…In addition, the FGS inequality still exhibits the sensitivity to witness the Bell diagonal states. More importantly, the fair sampling condition in steering inequalities needs to be invoked only on the untrusted subsystem [39], the detection efficiency in the measurement setting is required only to be 50% to close the detection loophole [40,41] (the detection efficiency is about 62% in our experiment). Compared to the fully device-independent protocol of an analog of the Bell-CHSH-type steering inequalities, in which the detection efficiency required is up to 83% [42], our approach needs less detector efficiency to certificate the steerablity of mixed states.…”

Section: Experimental Demonstration and Resultsmentioning

confidence: 99%

Experimental Demonstration of Fine-Grained Steering Inequality of Two-Qubit Mixed States

Bian

Yin²

2021

Photonics

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Quantum steering, as a cornerstone of quantum information, is usually used to witness the quantum correlation of bipartite and multi-partite states. Here, we experimentally demonstrate the quantum steering inequality of two-qubit mixed states based on the fine-grained uncertainty relation. Our experimental results show that the steering inequality has potent sensitivity to Werner states and Bell diagonal states. The steering strategy exhibits a strong ability to identify that Werner states are steerable when the decoherence coefficient a>12. Compared to the steering inequality obtained by another stratagem, the steering witness criteria of mixed states based on the fine-grained uncertainty relation demonstrated in our experiment has better precision and accuracy. Moreover, the detection efficiency in our measurement setup is only required to be 50% to close the detection loophole, which means our approach needs less detector efficiency to certificate the steerability of mixed states.

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Section: Experimental Demonstration and Resultsmentioning

confidence: 99%

Experimental Demonstration of Fine-Grained Steering Inequality of Two-Qubit Mixed States

Bian

Yin²

2021

Photonics

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“…A way to circumvent this difficulty is to introduce some minimal well-justified assumptions on the internal function of the detectors, which greatly simplifies the detection of GME states in practice but keeps some of the robusteness proper to the fully DI approach. In particular, this can be achieved with the help of the fair-sampling type assumptions [49,50]. A measurement device satisfies the weak fair-sampling assumption [49], if the process responsible for the occurrence of no-click events is independent of the choice of the measurement setting.…”

Section: Discussionmentioning

confidence: 99%

“…In particular, this can be achieved with the help of the fair-sampling type assumptions [49,50]. A measurement device satisfies the weak fair-sampling assumption [49], if the process responsible for the occurrence of no-click events is independent of the choice of the measurement setting. For our purpose this can be formalized in two equivalent ways.…”

Section: Discussionmentioning

confidence: 99%

“…If all the measurement devices in the experiment satisfy this assumption, it can be shown (see [49]), that the post-selected statistics on the produced state ρ is identical to the statistics produced by the filtered state…”

Section: Discussionmentioning

confidence: 99%

“…Simply rejecting these events (post-selection) opens the infamous detection loophole, and forbids the DI analysis of the post-selected measurement data. This problem is overcome here by introducing a minimal assumption on the internal functioning of the measurement devices, the so-called weak fair-sampling assumption [49], which is well justified in our setup, see methods.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Certification of Genuine Multipartite Entanglement with General and Robust Device-independent Witnesses

Zhang¹,

Zhang²,

Sekatski³

et al. 2021

Preprint

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Genuine multipartite entanglement represents the strongest type of entanglement, which is an essential resource for quantum information processing. Standard methods to detect genuine multipartite entanglement, e.g., entanglement witnesses, state tomography, or quantum state verification, require full knowledge of the Hilbert space dimension and precise calibration of measurement devices, which are usually difficult to acquire in an experiment. The most radical way to overcome these problems is to detect entanglement solely based on the Bell-like correlations of measurement outcomes collected in the experiment, namely, device-independently (DI). However, it is difficult to certify genuine entanglement of practical multipartite states in this way, and even more difficult to quantify it, due to the difficulty to identify optimal multipartite Bell inequalities and protocols tolerant to state impurity. In this work, we explore a general and robust DI method which can be applied to various realistic multipartite quantum state in arbitrary finite dimension, while merely relying on bipartite Bell inequalities. Our method allows us both to certify the presence of genuine multipartite entanglement and to quantify it. Several important classes of entangled states are tested with this method, leading to the detection of genuinely entangled states. We also certify genuine multipartite entanglement in weakly-entangled GHZ states, thus showing that the method applies equally well to less standard states.

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Calibration-independent bound on the unitarity of a quantum channel with application to a frequency converter

Bock,

Sekatski,

Bancal

et al. 2024

npj Quantum Inf

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We report on a method to certify a unitary operation with the help of source and measurement apparatuses whose calibration throughout the certification process needs not be trusted. As in the device-independent paradigm our certification method relies on a Bell test and requires no assumption on the underlying Hilbert space dimension, but it removes the need for high detection efficiencies by including the single additional assumption that non-detected events are independent of the measurement settings. The relevance of the proposed method is demonstrated experimentally by bounding the unitarity of a quantum frequency converter. The experiment starts with the heralded creation of a maximally entangled two-qubit state between a single 40Ca+ ion and a 854 nm photon. Entanglement preserving frequency conversion to the telecom band is then realized with a non-linear waveguide embedded in a Sagnac interferometer. The resulting ion-telecom photon entangled state is assessed by means of a Bell-CHSH test from which the quality of the frequency conversion is quantified. We demonstrate frequency conversion with an average certified fidelity of ≥84% and an efficiency ≥3.1 × 10−6 at a confidence level of 99%. This ensures the suitability of the converter for integration in quantum networks from a trustful characterization procedure.

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How post-selection affects device-independent claims under the fair sampling assumption

Cited by 13 publications

References 58 publications

Experimental Demonstration of Fine-Grained Steering Inequality of Two-Qubit Mixed States

Experimental Demonstration of Fine-Grained Steering Inequality of Two-Qubit Mixed States

Certification of Genuine Multipartite Entanglement with General and Robust Device-independent Witnesses

Calibration-independent bound on the unitarity of a quantum channel with application to a frequency converter

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