Steering a single system sequentially by multiple observers

Sasmal, Souradeep; Das, Debarshi; Mal, Shiladitya; Majumdar, A. S.

doi:10.1103/physreva.98.012305

Cited by 83 publications

(103 citation statements)

References 31 publications

(68 reference statements)

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“…Note that it was conjectured in Ref. [19] that N Bobs can exhibit steering with respect to Alice when steering is probed through an N -settings steering inequality, in the case d = 2. From our results, which are admittedly restricted to the maximally entangled state together with specific measurements, it seems that this conjecture is not true.…”

Section: A All Measurementsmentioning

confidence: 99%

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Unbounded sequence of observers exhibiting Einstein-Podolsky-Rosen steering

Designolle

Hirsch

et al. 2019

Phys. Rev. A

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A sequential steering scenario is investigated, where multiple Bobs aim at demonstrating steering using successively the same half of an entangled quantum state. With isotropic entangled states of local dimension d, the number of Bobs that can steer Alice is found to be N Bob ∼ d/ log d, thus leading to an arbitrary large number of successive instances of steering with independently chosen and unbiased inputs. This scaling is achieved when considering a general class of measurements along orthonormal bases, as well as complete sets of mutually unbiased bases. Moreover, we show that similar results can be obtained in an anonymous sequential scenario, where none of the Bobs know their position in the sequence. Finally, we briefly discuss the implication of our results for sequential tests of Bell nonlocality.

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Section: A All Measurementsmentioning

confidence: 99%

“…This motivated further work exploring the potential of these ideas for randomness generation [13] and their classical communication cost [14], and led to experimental demonstrations [15,16]. More recently, these ideas were extended to other types of quantum correlations [17][18][19]. Specifically, Ref.…”

Section: Introductionmentioning

confidence: 99%

Unbounded sequence of observers exhibiting Einstein-Podolsky-Rosen steering

Designolle

Hirsch

et al. 2019

Phys. Rev. A

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“…Hence, in order to address the aforementioned problem with n Charlies, the measurements of the first (n − 1) Charlies should be weak. In the present study we will follow the unsharp version of the weak measurement formalism discussed in [12,18]. For completeness we briefly recapitulate in the following the weak measurement scheme introduced in [11] and then unsharp version of that considered in [12,18].…”

Section: Setting Up the Scenario Via Weak Measurement Formalismmentioning

confidence: 99%

“…when +1 and −1 outcomes are obtained, respectively. The quality factor F and the precision G defined in the context of aforementioned weak measurement formalism are related to the unsharp measurement formalism through F = √ 1 − λ 2 and G = λ [12,18]. Hence, it is evident that the sharpness parameter λ characterizes the precision of the measurement.…”

Section: Setting Up the Scenario Via Weak Measurement Formalismmentioning

confidence: 99%

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Sharing of tripartite nonlocality by multiple observers measuring sequentially at one side

Saha

Das

Sasmal

et al. 2019

Quantum Inf Process

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Standard tripartite nonlocality and genuine tripartite nonlocality can be detected by the violations of Mermin inequality and Svetlichny inequality, respectively. Since tripartite quantum nonlocality has novel applications in quantum information and quantum computation, it is important to investigate whether more than three observers can share tripartite nonlocality, simultaneously. In the present study we answer this question in the affirmative. In particular, we consider a scenario where three spin-1 2 particles are spatially separated and shared between Alice, Bob and multiple Charlies. Alice performs measurements on the first particle; Bob performs measurements on the second particle and multiple Charlies perform measurements on the third particle sequentially. In this scenario we investigate how many Charlies can simultaneously demonstrate standard tripartite nonlocality and genuine tripartite nonlocality with single Alice and single Bob. The interesting result revealed by the present study is that at most six Charlies can simultaneously demonstrate standard tripartite nonlocality with single Alice and single Bob. On the other hand, at most two Charlies can simultaneously demonstrate genuine tripartite nonlocality with single Alice and single Bob. Hence, the present study shows that standard tripartite nonlocality can be simultaneously shared by larger number of Charlies compared to genuine tripartite nonlocality in the aforementioned scenario, which implies that standard tripartite nonlocality is more effective than genuine tripartite nonlocality in the context of simultaneous sharing by multiple observers.

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Sharing quantum steering among multiple Alices and Bobs via a two-qubit Werner state

Han

Xiao

et al. 2021

Quantum Inf Process

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Quantum steering, a type of quantum correlation with unique asymmetry, has important applications in asymmetric quantum information tasks. We consider a new quantum steering scenario in which one half of a two-qubit Werner state is sequentially measured by multiple Alices and the other half by multiple Bobs. We find that the maximum number of Alices who can share steering with a single Bob increases from 2 to 5 when the number of measurement settings N increases from 2 to 16. Furthermore, we find a counterintuitive phenomenon that for a fixed N, at most 2 Alices can share steering with 2 Bobs, while 4 or more Alices are allowed to share steering with a single Bob. We further analyze the robustness of the steering sharing by calculating the required purity of the initial Werner state, the lower bound of which varies from 0.503(1) to 0.979(5). Finally, we show that our both-sides sequential steering sharing scheme can be applied to control the steering ability, even the steering direction, if an initial asymmetric state or asymmetric measurement is adopted. Our work gives insights into the diversity of steering sharing and can be extended to study the problems such as genuine multipartite quantum steering when the sequential unsharp measurement is applied.

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Steering a single system sequentially by multiple observers

Cited by 83 publications

References 31 publications

Unbounded sequence of observers exhibiting Einstein-Podolsky-Rosen steering

Unbounded sequence of observers exhibiting Einstein-Podolsky-Rosen steering

Sharing of tripartite nonlocality by multiple observers measuring sequentially at one side

Sharing quantum steering among multiple Alices and Bobs via a two-qubit Werner state

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