Manipulating the quantum steering direction with sequential unsharp measurements

Han, Xin-Hong; Qu, Hui-Chao; Fan, Xuan; Xiao, Ya; Gu, Yongjian

doi:10.1103/physreva.106.042416

Cited by 7 publications

(3 citation statements)

References 47 publications

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“…Until now, all researches aimed at improving the efficiency of EPR steering has been restricted to local measurements [25][26][27][28][29] , In the case of local measurements, each observer measures the qubit in the hand. Mathematically, each observer's measurement results can be obtained by measuring his or her respective reduced density matrices.…”

Section: Activationmentioning

confidence: 99%

Activation of Einstein–Podolsky–Rosen steering sharing with unsharp nonlocal measurements

Han,

Qian,

Dong

et al. 2024

Sci Rep

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Einstein–Podolsky–Rosen (EPR) steering is commonly shared among multiple observers by utilizing unsharp measurements. Nevertheless, their usage is restricted to local measurements and does not encompass all nonlocal measurement-based cases. In this work, a method for finding beneficial local measurement settings has been expanded to include nonlocal measurement cases. This method is applicable for any bipartite state and offers benefits even in scenarios with a high number of measurement settings. Using the Greenberger–Horne–Zeilinger state as an illustration, we show that employing unsharp nonlocal measurements can activate the phenomenon of steering sharing in contrast to using local measurements. Furthermore, our findings demonstrate that nonlocal measurements with unequal strength possess a greater activation capability compared to those with equal strength. Our activation method generates fresh concepts for conservation and recycling quantum resources.

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Section: Activationmentioning

confidence: 99%

Activation of Einstein–Podolsky–Rosen steering sharing with unsharp nonlocal measurements

Han,

Qian,

Dong

et al. 2024

Sci Rep

Self Cite

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“…They found that by adjusting the measurement sharpness, the former party can extract sufficient nonlocality and maintain enough entanglement, enabling sequential parties to share Bell nonlocality simultaneously [16]. Since then, unsharp measurement has been widely applied in sharing quantum correlations [17], such as standard Bell nonlocality [18][19][20][21][22][23], network nonlocality [24][25][26][27][28][29], steering [30][31][32][33][34][35][36][37][38][39], entanglement [40][41][42][43][44], coherence [45,46], and contextuality [47,48]. Moreover, it has been observed that these shared quantum correlations are closely connected to numerous quantum information tasks, including quantum random access code [49][50][51][52], randomness certification [53][54][55], self-testing [56,57] and revealing 'hidden' nonlocality [58].…”

Section: Introductionmentioning

confidence: 99%

Experimental sharing of Bell nonlocality with projective measurements

Xiao,

Xin Rong,

Wang

et al. 2024

New J. Phys.

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\textcolor{red}{In the standard Bell experiment, two parties perform local projective measurements on a shared pair of entangled qubits to generate nonlocal correlations. However, these measurements completely destroy the entanglement, rendering the post-measurement state unable for subsequent use. For a long time, it was believed that only unsharp measurements can be used to share quantum correlations. Remarkably, recent research has shown that classical randomness assisted projective measurements are sufficient for sharing nonlocality} [Phys. Rev. Lett. 129, 230402 (2022)]. Here, by stochastically combining no more than two different projective measurement strategies, we report an \textcolor{red}{experimental} observation of \textcolor{red}{double Clauser-Horne-Shimony-Holt (CHSH) inequality violations with two measurements in a sequence made on each pair of maximally and partially entangled} polarization photons. Our results reveal that the double violation achieved by partially entangled states can be 11 standard deviations larger than that achieved by maximally entangled ones. Our scheme eliminates the requirement for entanglement assistance in previous unsharp-measurement-based sharing schemes, making it experimentally easier. Our work provides possibilities for sharing other types of quantum correlations in various physical systems with projective measurements.

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“…Steering is intrinsically a directional form of correlation. The problem of manipulating the quantum steering direction with sequential unsharp measurements has recently been investigated in [46].…”

Section: Introductionmentioning

confidence: 99%

Sharing EPR steering between sequential pairs of observers

Liang

Fei

2023

J. Phys. A: Math. Theor.

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The recycling of quantum correlations has attracted widespread attention both theoretically and experimentally. Previous works show that bilateral sharing of nonlocality is impossible under mild measurement strategy and 2-qubit entangled state can be used to witness entanglement arbitrary many times by sequential and independent pairs of observers. However, less is known about the bilateral sharing of EPR steering yet. Here, we aim at investigating the EPR steering sharing between sequential pairs of observers. We show that an unbounded number of sequential Alice-Bob pairs can share the EPR steering as long as the initially shared state is an entangledtwo-qubit pure state. The claim is also true for particular class of mixed entangled states.

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Manipulating the quantum steering direction with sequential unsharp measurements

Cited by 7 publications

References 47 publications

Activation of Einstein–Podolsky–Rosen steering sharing with unsharp nonlocal measurements

Activation of Einstein–Podolsky–Rosen steering sharing with unsharp nonlocal measurements

Experimental sharing of Bell nonlocality with projective measurements

Sharing EPR steering between sequential pairs of observers

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