Fair-sampling assumption is not necessary for testing local realism

Berry, Dominic W.; Jeong, Hyunseok; Stobińska, Magdalena; Ralph, T. C.

doi:10.1103/physreva.81.012109

Cited by 28 publications

(45 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For instance, Eq. (2) does not require the so-called fair-sampling condition [24,26], which is typically assumed in standard Bell experiments involving postselection to ensure that the conclusive/detected events are representative of the underlying quantum system. Most interestingly, Fig.…”

Section: Connection To Quantum State Discriminationmentioning

confidence: 99%

“…For our purposes, we de- * limc@ornl.gov fine such quantum inputs as quantum states that are indistinguishable at the level of local operations and shared randomness (LOSR) [10], but distinguishable at the level of local quantum measurements assisted with shared entanglement (henceforth referred to as quantum strategies). In particular, our theoretical contribution recognizes that semi-quantum Bell inequalities using locally-indistinguishable quantum inputs can acquire the following two interesting properties: (1) the ability to safely perform postselection and (2) the ability to achieve higher Bell violations with decreasing measurement efficiencies [21].The first property is based on the fact that postselection strategies due to the detection loophole [22][23][24] are local filtering processes assisted with shared randomness. Thus by the above definition, it is impossible for LOSR models to produce postselected correlations that are semi-quantum nonlocal-even if arbitrarily low measurement efficiencies are allowed.…”

mentioning

confidence: 99%

“…The first property is based on the fact that postselection strategies due to the detection loophole [22][23][24] are local filtering processes assisted with shared randomness. Thus by the above definition, it is impossible for LOSR models to produce postselected correlations that are semi-quantum nonlocal-even if arbitrarily low measurement efficiencies are allowed.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Optimality of semiquantum nonlocality in the presence of high inconclusive rates

Lim

2016

Phys. Rev. A

View full text Add to dashboard Cite

Quantum nonlocality is a counterintuitive phenomenon that lies beyond the purview of causal influences. Recently, Bell inequalities have been generalized to the case of quantum inputs, leading to a powerful family of semi-quantum Bell inequalities that are capable of detecting any entangled state. Here, we focus on a different problem and investigate how the local-indistinguishability of quantum inputs and postselection may affect the requirements to detect semi-quantum nonlocality. To this end, we consider a semi-quantum nonlocal game based on locally-indistinguishable qubit inputs and derive its postselected local and quantum bounds by using a novel connection to the local-distinguishability of quantum states. Interestingly, we find that the postselected local bound is independent of the measurement efficiency and that the Bell violation increases with lower measurement efficiencies.It is known that in quantum physics, there exist experiments in which correlations from measurements on entangled systems are at odds with our causal world views. These correlations may be verified by using a family of statistical tests called Bell inequalities [1, 2], which are linear constraints on the set of correlations that are compatible with the principle of local causes [3]. In other words, if the correlations violate a Bell inequality, then the underlying physics must be nonlocal in nature. Remarkably, apart from their foundational significance, Bell inequalities have also found practical applications in quantum cryptography and quantum state estimation [4][5][6][7][8][9]. For these reasons, quantum nonlocality is one of the most widely studied topics in quantum information science.Recently, a new paradigm called semi-quantum nonlocality has emerged [10], where observers use quantum inputs-instead of classical inputs-to specify their desired measurement settings. Interestingly, by doing so, all entangled states are "nonlocal", in that for any entangled state there is always a semi-quantum Bell inequality with which violation is achieved. This feature suggests that certain semi-quantum Bell inequalities are strong entanglement witnesses and thus could provide an unprecedented level of confidence in detecting entanglement using untrusted measurement devices. For instance, see Ref.[11] for a generic procedure that converts entanglement witnesses into measurement-device-independent entanglement witnesses, and Ref. [12] for the corresponding proof-of-principle experiment. See also Refs. [13,14] for the connection to quantum steering [15].On a more general level, semi-quantum nonlocality admits the possibility of working with locallyindistinguishable quantum inputs, a notion that is central to local quantum state discrimination [16][17][18] and quantum data hiding [19,20]. For our purposes, we de- * limc@ornl.gov fine such quantum inputs as quantum states that are indistinguishable at the level of local operations and shared randomness (LOSR) [10], but distinguishable at the level of local quantum measurements assisted with shar...

show abstract

Section: Connection To Quantum State Discriminationmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Optimality of semiquantum nonlocality in the presence of high inconclusive rates

Lim

2016

Phys. Rev. A

View full text Add to dashboard Cite

show abstract

“…In the experimental scenario where noiseless amplification can only be implemented as a probabilistic heralded process, the implementation of the amplification stage after the local operations makes the detection of the correct amplified ECS state a probabilistic event which, in turns, opens up a loophole in the test to be run. In fact, this implies that only the cases where the amplification operation is successful for both involved parties of the state at hand should then be considered for the nonlocality test [23]. Such postselection step requires us to invoke a fair-sampling assumption, similarly to what is done for the well-known detection loophole in Bell-CHSH inequalities, an assumption that we will maintain throughout the paper.…”

mentioning

confidence: 99%

Violation of Bell's inequalities with preamplified homodyne detection

Torlai¹,

McKeown²,

Marek³

et al. 2013

Phys. Rev. A

View full text Add to dashboard Cite

We show that the use of probabilistic noiseless amplification in entangled coherent state-based schemes for the test of quantum nonlocality provides substantial advantages. The threshold amplitude to falsify a Bell-CHSH nonlocality test, in fact, is significantly reduced when amplification is embedded into the test itself. Such a beneficial effect holds also in the presence of detection inefficiency. Our study helps in affirming noiseless amplification as a valuable tool for coherent information processing and the generation of strongly nonclassical states of bosonic systems. [3]. However, Banaszek and Wódkiewicz later devised a phase-space approach based on the statistics gathered from the measurement of photon parity operators [4], demonstrating the key role played by non-Gaussianity in the revelation of the nonlocal feature of entangled two-mode states. This sort of approach finds its complement in nonlocality tests performed using Gaussian operations and measurements on non-Gaussian states, such as entangled coherent states (ECSs) [5], or de-Gaussified two-mode states achieved by resorting to photon subtraction (photon addition) [6][7][8][9][10]. On the other hand, recently it has been shown that the combination of Gaussian and nonGaussian measurements can lead to significant violations of local realistic models using continuous-variable systems [11,12].In particular, the nonlocal nature of an ECS has been extensively studied in past years, addressing tests based on effective pseudospin operators, photon parity operators, effective rotations, and dichotomized homodyne measurements, even in the presence of decoherence [13][14][15][16][17]. The latter approaches have been used for the violation of Bell-CHSH inequality [18] by states having a very large thermal occupation number [19], thus showing the possibility to reveal their nonclassical character, even under mechanisms that, naively, would be expected to wash out any quantumness. A conspicuous feature of ECS-based tests using homodyne measurements is that the violation of a Bell-CHSH inequality occurs only for coherent-state components having amplitude larger than a given threshold. Under realistic conditions, the threshold is typically determined by the operative conditions (detection inefficiencies and purity of the state resource, among other factors) under which the test is run. In light of the experimental difficulties encountered in the generation of ECS of largeamplitude components [20], it is clearly desirable to identify viable strategies for the falsification of local realistic theories with lower amplitude thresholds, so as to ease the experimental efforts required for such an important task.In this paper we report a test of local realism for ECS of light having an arbitrarily small amplitude, supplemented by the application of local noiseless amplification to the components of the system, after the implementation of the necessary local operations that are part of the Bell test [21,22]. By increasing the amplitude of the coherent-state componen...

show abstract

“…In our considerations we took into account experimental imperfections in the form of losses. Further analysis of the possibility of loophole-free violation and the role of fair sampling assumption similar to [30] remains to be addressed.Our approach is very likely to be developed and exploited in several quantum information tasks which are of great technological interest. For example, recently the idea of partial characterization of the devices has been developed and has been expressed in terms of semi-deviceindependent scenarios [31].…”

mentioning

confidence: 99%

Quantum steering inequality with tolerance for measurement-setting-errors: experimentally feasible signature of unbounded violation

Stobińska¹

2017

Quantum Information and Measurement (QIM) 2017

Self Cite

View full text Add to dashboard Cite

Quantum steering is a relatively simple test for quantumness of correlations, proving that the values of quantum-mechanical measurement outcomes come into being only in the act of measurement. By exploiting quantum correlations Alice can influence -steer -Bob's physical system in a way inaccessible in classical world, leading to violation of some inequalities. Demonstrating this and similar quantum effects for systems of increasing size, approaching even the classical limit, is a long-standing challenging problem. Here we provide experimentally feasible signature of unbounded violation of a steering inequality. We derive its universal form where tolerance for measurement-setting-errors is explicitly build-in by means of the Deutsch-Maassen-Uffink uncertainty relation. Then, generalizing the mutual unbiasedness, we apply the inequality to the multi-singlet and multi-particle bipartite Bell-state. However, the method is general and opens the possibility of employing multi-particle bipartite steering for randomness certification and development of quantum technologies, e.g. random access codes.In their famous paper, Einstein, Podolsky and Rosen (EPR) highlighted the phenomenon of entanglement [1]: it is possible to see perfect correlations between measurement outcomes obtained by two observers, Alice and Bob, at distant locations, while for each observer his/her outcomes appear to be statistically random. These are the EPR correlations. Validation of entanglement requires designing a specific experimental scenario where measurements on a quantum state give outcomes which violate a classical inequality. The inequality can be constructed, for example, on the basis of probability distribution satisfying the Kolmogorov axioms. Its unbounded violation is equivalent to observation of the EPR correlations which become more and more pronounced when size of a system increases, reaching even classical limit of macroscopic population. This is very challenging to accomplish in the paradigm of Bell-nonlocality testing: if specific observables with (2 log 2 d ) d settings and d possible outcomes are used, bipartite quantum states with local Hilbert space dimension d can violate a Bell inequality by a factor of O[2], later improved to [3][4][5]. Thus, an unbounded violation of a Bell inequality requires exponentially many observables (or equivalently, settings). According to the monogamy relation [6], this scaling can be improved only up to the linear one (see the Supplementary Information). How- * fizar@ug.edu.pl † aburacze@gmail.com ‡ pawel@mif.pg.gda.pl § magdalena.stobinska@gmail.com; Corresponding author ever, the present results are still far from this limit and this makes them purely academic as far as the experimental perspective is concerned [7]. In case of quantum steering, the task has been found to be less difficult: violation of a steering inequality by a factor of O √ d requires d + 1 observables in the form of mutually unbiased bases (MUBs) [8]. However, this scenario necessitates the complementarity relation among...

show abstract

Fair-sampling assumption is not necessary for testing local realism

Cited by 28 publications

References 53 publications

Optimality of semiquantum nonlocality in the presence of high inconclusive rates

Optimality of semiquantum nonlocality in the presence of high inconclusive rates

Violation of Bell's inequalities with preamplified homodyne detection

Quantum steering inequality with tolerance for measurement-setting-errors: experimentally feasible signature of unbounded violation

Contact Info

Product

Resources

About