Does large quantum Fisher information imply Bell correlations?

Fröwis, Florian; Fadel, Matteo; Treutlein, Philipp; Gisin, Nicolas; Brunner, Nicolás

doi:10.1103/physreva.99.040101

Cited by 27 publications

(15 citation statements)

References 38 publications

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“…Besides its fundamental relevance for quantum-enhanced precision measurements, the QFI is of great interest for the characterisation of quantum many-body systems 14 , 15 and gives rise to an efficient and experimentally accessible witness for multipartite entanglement 12 , 13 , 16 , but so far, its relation to steering has remained elusive. It has been a long-standing open problem to determine if quantum correlations stronger than entanglement, such as steering or Bell correlations, play a role in metrology 17 .…”

Section: Introductionmentioning

confidence: 99%

Metrological complementarity reveals the Einstein-Podolsky-Rosen paradox

2021

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The Einstein-Podolsky-Rosen (EPR) paradox plays a fundamental role in our understanding of quantum mechanics, and is associated with the possibility of predicting the results of non-commuting measurements with a precision that seems to violate the uncertainty principle. This apparent contradiction to complementarity is made possible by nonclassical correlations stronger than entanglement, called steering. Quantum information recognises steering as an essential resource for a number of tasks but, contrary to entanglement, its role for metrology has so far remained unclear. Here, we formulate the EPR paradox in the framework of quantum metrology, showing that it enables the precise estimation of a local phase shift and of its generating observable. Employing a stricter formulation of quantum complementarity, we derive a criterion based on the quantum Fisher information that detects steering in a larger class of states than well-known uncertainty-based criteria. Our result identifies useful steering for quantum-enhanced precision measurements and allows one to uncover steering of non-Gaussian states in state-of-the-art experiments.

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Section: Introductionmentioning

confidence: 99%

Metrological complementarity reveals the Einstein-Podolsky-Rosen paradox

2021

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“…In future works, it would be interesting to investigate how the spin-squeezing matrix could give a quantification of entanglement through a connection with entanglement monotones [40,55], and the metrological advantage provided by correlations stronger than entanglement [56][57][58][59].…”

Section: Discussionmentioning

confidence: 99%

Multiparameter quantum metrology and mode entanglement with spatially split nonclassical spin states

Fadel¹,

Yadin²,

Mao³

et al. 2022

Preprint

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We identify the multiparameter sensitivity of split nonclassical spin states, such as spin-squeezed and Dicke states spatially distributed into several addressable modes. Analytical expressions for the spin-squeezing matrix of a family of states that are accessible by current atomic experiments reveal the quantum gain in multiparameter metrology, as well as the optimal strategies to maximize the sensitivity. We further study the mode entanglement of these states by deriving a witness for genuine k-partite mode entanglement from the spin-squeezing matrix. Our results highlight the advantage of mode entanglement for distributed sensing, and outline optimal protocols for multiparameter estimation with nonclassical spatially-distributed spin ensembles.

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“…For this reason, states with ξ 2 < 1 can achieve a quantum enhancement beyond the standard quantum limit in metrology measurements [16] and the entanglement revealed by this condition is metrologically useful. This approach can be extended to multipartite entanglement [4,35], Bell nonlocality [36], and to analyze the multimode entanglement structure in addressable systems of arbitrary dimension [24,25].…”

Section: B Spin Squeezing Particle-entanglement Criterionmentioning

confidence: 99%

Relating spin squeezing to multipartite entanglement criteria for particles and modes

Fadel,

Gessner

2020

Preprint

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Entanglement witnesses based on first and second moments exist in the form of spin-squeezing criteria for the detection of particle entanglement from collective measurements, and in form of modified uncertainty relations for the detection of mode entanglement or steering. By revealing a correspondence between them, we show that metrologically useful spin squeezing reveals multimode entanglement in symmetric spin states that are distributed into addressable modes. We further derive tight state-independent multipartite entanglement bounds on the spin-squeezing coefficient and point out their connection to widely-used entanglement criteria that depend on the state's polarization. Our results are relevant for state-of-the-art experiments where symmetric entangled states are distributed into a number of addressable modes, such as split spin-squeezed Bose-Einstein condensates.

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Does large quantum Fisher information imply Bell correlations?

Cited by 27 publications

References 38 publications

Metrological complementarity reveals the Einstein-Podolsky-Rosen paradox

Metrological complementarity reveals the Einstein-Podolsky-Rosen paradox

Multiparameter quantum metrology and mode entanglement with spatially split nonclassical spin states

Relating spin squeezing to multipartite entanglement criteria for particles and modes

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