Observation of Nonlocality Sharing among Three Observers with One Entangled Pair via Optimal Weak Measurement

Hu, Meng-Jun; Zhou, Zhiyuan; Hu, Xiaomin; Li, Chuan‐Feng; Guo, Guang‐Can; Zhang, Yongsheng

doi:10.48550/arxiv.1609.01863

Cited by 11 publications

(16 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is then unclear whether with present or near future technology sequential protocols will provide a significant practical advantage over simpler protocols based on standard Bell tests. However, the first experimental works observing non-local correlations in the sequential scenario have recently been reported [23,24]. In any case, the main implications of our work are fundamental: It shows that a single pair of pure entangled qubits is a potentially unbounded source of certifiable random bits when performing sequences of measurements on it.…”

mentioning

confidence: 78%

Unbounded randomness certification using sequences of measurements

et al. 2017

View full text Add to dashboard Cite

Unpredictability, or randomness, of the outcomes of measurements made on an entangled state can be certified provided that the statistics violate a Bell inequality. In the standard Bell scenario where each party performs a single measurement on its share of the system, only a finite amount of randomness, of at most 4 log 2 d bits, can be certified from a pair of entangled particles of dimension d. Our work shows that this fundamental limitation can be overcome using sequences of (nonprojective) measurements on the same system. More precisely, we prove that one can certify any amount of random bits from a pair of qubits in a pure state as the resource, even if it is arbitrarily weakly entangled. In addition, this certification is achieved by near-maximal violation of a particular Bell inequality for each measurement in the sequence.Introduction.-Bell's theorem [1] has shown that the predictions of quantum mechanics demonstrate non-locality. That is, they cannot be described by a theory in which there are objective properties of a system prior to measurement that satisfy the no-signalling principle (sometimes referred to as "local realism"). Thus, if one requires the no-signalling principle to be satisfied at the operational level then the outcomes of measurements demonstrating non-locality must be unpredictable [1][2][3]. This unpredictability, or randomness, is not the result of ignorance about the system preparation but is intrinsic to the theory.Although the connection between quantum non-locality (via Bell's theorem) and the existence of intrinsic randomness is well known [1][2][3][4] it was analyzed in a quantitative way only recently [5,6]. It was shown how to use nonlocality (probability distributions that violate a Bell inequality) to certify the unpredictability of the outcomes of certain physical processes. This was termed device-independent randomness certification, because the certification only relies on the statistical properties of the outcomes and not on how they were produced. The development of information protocols exploiting this certified form of randomness, such as deviceindependent randomness expansion [5][6][7] and amplification protocols [8,9], followed.Entanglement is a necessary resource for quantum nonlocality, which in turn is required for randomness certification. It is thus crucial to understand qualitatively and quantitatively how these three fundamental quantities relate to one another. In our work, we focus on asking how much certifiable randomness can be obtained from a single entangled state as a resource. Progress has been made in this direction for entangled states shared between two parties, Alice (A) and Bob (B), in the standard scenario where each party makes a single measurement on his share of the system and then discards it. An argument adapted from Ref. [10] shows that either of the two parties, A or B can certify at most 2log 2 d bits of randomness [11], where d is the dimension of the local Hilbert space the state lives in, which in turn implies a bound of 4log 2 d b...

show abstract

mentioning

confidence: 78%

Unbounded randomness certification using sequences of measurements

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Note added -While we were completing our work we became aware that a similar manuscript, showing the experimental violation a double Bell inequality, was recently posted on arXiv [17]. particular, for small angle θ of the thin glass plate we can omit the refraction and consider the following model for φ φ…”

Section: Introduction -mentioning

confidence: 99%

Three-observer Bell inequality violation on a two-qubit entangled state

Schiavon

Calderaro

Pittaluga

et al. 2017

Quantum Sci. Technol.

View full text Add to dashboard Cite

Bipartite Bell inequalities can be simultaneously violated by two different pairs of observers when weak measurements and signaling is employed. Here we experimentally demonstrate the violation of two simultaneous CHSH inequalities by exploiting a two-photon polarization maximally entangled state. Our results demonstrate that large double violation is experimentally achievable. Our demonstration may have impact for Quantum Key Distribution or certification of Quantum Random Number generators based on weak measurements.

show abstract

“…In particular, no-signalling cannot be enforced in scenarios such as the case when half of an entangled pair of two particles is shared by one observer and another half is shared among several observers who measure their particle sequentially and independently of each other [17]. It has been shown in [18] that if a maximally entangled state is shared between a Bob at one end and several Alices at the other, a maximum of two Alices can exhibit QM violation of the Bell-CHSH inequality [19], a result that was conjectured numerically earlier [17], and later on also demonstrated experimentally [20,21]. In case of quantum steering, it has been recently shown [22] that at most two Alices can demonstrate quantum steering in the same scenario using the CHSH-analogous steering inequality which is a necessary and sufficient crite-rion for steering [23] in such cases.…”

Section: Introductionmentioning

confidence: 82%

“…Our results indicate a qualitative difference between the l 1 -norm of coherence with the other two measures, i.e., the relative entropy and skew information, when coherence is employed as a resource for generating nonlocal advantage in information processing tasks. It is known from earlier results that Bell-CHSH non-locality can be shared between at most two observers at one end [17,18,20,21], whereas quantum steering has been conjectured to be demonstrated with at most n number of observers at one end when a steering inequality with nmeasurement settings per party is employed [22]. Based on these results it might be expected that the bound on the number of observers is inherently connected to the strength of the nonlocal correlation, with increase in the strength of the correlation causing the number of observers being able to share it to be decreased.…”

Section: Discussionmentioning

confidence: 99%

Sharing of nonlocal advantage of quantum coherence by sequential observers

Datta

Majumdar

2018

Phys. Rev. A

View full text Add to dashboard Cite

Non-local Advantage of Quantum Coherence(NAQC) or steerability of local quantum coherence is a strong non-local resource based on coherence complementarity relations. In this work, we provide an upper bound on the number of observers who can independently steer the coherence of the observer in the other wing in a scenario where half of an entangled pair of spin-1 2 particles is shared between a single observer (Bob) in one wing and several observers (Alices) on the other, who can act sequentially and independently of each other. We consider one-parameter dichotomic POVMs for the Alices and mutually unbiased basis in which Bob measures coherence in case of the maximally entangled bipartite qubit state. We show that not more than two Alices can exhibit NAQC when l1-norm of coherence measure is probed, whereas for two other measures of coherence, only one Alice can reveal NAQC within the same framework.

show abstract

Observation of Nonlocality Sharing among Three Observers with One Entangled Pair via Optimal Weak Measurement

Cited by 11 publications

References 35 publications

Unbounded randomness certification using sequences of measurements

Unbounded randomness certification using sequences of measurements

Three-observer Bell inequality violation on a two-qubit entangled state

Sharing of nonlocal advantage of quantum coherence by sequential observers

Contact Info

Product

Resources

About