scholarly journals Single-copy activation of Bell nonlocality via broadcasting of quantum states

Quantum ◽  
2021 ◽  
Vol 5 ◽  
pp. 499
Author(s):  
Joseph Bowles ◽  
Flavien Hirsch ◽  
Daniel Cavalcanti
Keyword(s):  
Single Copy ◽  
Quantum Correlations ◽  
The State ◽  
Mixed States ◽  
Variable Model ◽  
Variable Theory ◽  
Hidden Variable ◽  
Bell Nonlocality ◽  
Nonlocal Nature ◽  
Local Hidden Variable

Activation of Bell nonlocality refers to the phenomenon that some entangled mixed states that admit a local hidden variable model in the standard Bell scenario nevertheless reveal their nonlocal nature in more exotic measurement scenarios. We present such a scenario that involves broadcasting the local subsystems of a single-copy of a bipartite quantum state to multiple parties, and use the scenario to study the nonlocal properties of the two-qubit isotropic state:ρα=α|Φ+⟩⟨Φ+|+(1−α)14.We present two main results, considering that Nature allows for (i) the most general no-signalling correlations, and (ii) the most general quantum correlations at the level of any hidden variable theory. We show that the state does not admit a local hidden variable description for α>0.559 and α>12, in cases (i) and (ii) respectively, which in both cases provides a device-independent certification of the entanglement of the state. These bounds are significantly lower than the previously best-known bound of 0.697 for both Bell nonlocality and device-independent entanglement certification using a single copy of the state. Our results show that strong examples of non-classicality are possible with a small number of resources.

scholarly journals Review on investigating the possibility of local hidden variable theories-quantum teleportation

2018 ◽  
Vol 6 (1) ◽  
pp. 1
Author(s):  
Dorcas Attuabea Addo ◽  
Steven Abel ◽  
Richard Kwame Ansah ◽  
Isaac Nkrumah
Keyword(s):  
Single Particle ◽  
Quantum Teleportation ◽  
Entangled State ◽  
Bell’S Inequality ◽  
Variable Theory ◽  
Bell's Inequality ◽  
Hidden Variable ◽  
Hidden Variable Theories ◽  
Nonlocal Nature ◽  
Local Hidden Variable

The core of the paper was to investigate the possibility of local hidden variable theory and its application in quantum teleportation. We reviewed literature on the Bell's inequality which is necessary for quantum teleportation. Quantum teleportation utilises a single-particle entangled state which can be successfully achieved by the application of the locality assumption which leads to Bell's inequality. A violation of the Bell's inequality signifies the nonlocal nature of a single particle useful for quantum teleportation.

scholarly journals Bounding the Plausibility of Physical Theories in a Device-Independent Setting via Hypothesis Testing

Entropy ◽  
2019 ◽  
Vol 21 (2) ◽  
pp. 185 ◽  
Author(s):  
Yeong-Cherng Liang ◽  
Yanbao Zhang
Keyword(s):  
Hypothesis Testing ◽  
Hypothesis Test ◽  
Quantum Correlations ◽  
Ratio Method ◽  
Empirical Observation ◽  
Hidden Variable ◽  
Apparent Violation ◽  
Hidden Variable Theories ◽  
Experimental Trials ◽  
Local Hidden Variable

The device-independent approach to physics is one where conclusions about physical systems (and hence of Nature) are drawn directly and solely from the observed correlations between measurement outcomes. This operational approach to physics arose as a byproduct of Bell’s seminal work to distinguish, via a Bell test, quantum correlations from the set of correlations allowed by local-hidden-variable theories. In practice, since one can only perform a finite number of experimental trials, deciding whether an empirical observation is compatible with some class of physical theories will have to be carried out via the task of hypothesis testing. In this paper, we show that the prediction-based-ratio method—initially developed for performing a hypothesis test of local-hidden-variable theories—can equally well be applied to test many other classes of physical theories, such as those constrained only by the nonsignaling principle, and those that are constrained to produce any of the outer approximation to the quantum set of correlations due to Navascués-Pironio-Acín. We numerically simulate Bell tests using hypothetical nonlocal sources of correlations to illustrate the applicability of the method in both the independent and identically distributed (i.i.d.) scenario and the non-i.i.d. scenario. As a further application, we demonstrate how this method allows us to unveil an apparent violation of the nonsignaling conditions in certain experimental data collected in a Bell test. This, in turn, highlights the importance of the randomization of measurement settings, as well as a consistency check of the nonsignaling conditions in a Bell test.

scholarly journals Incompatible quantum measurements admitting a local-hidden-variable model

2016 ◽  
Vol 93 (5) ◽  
Author(s):  
Marco Túlio Quintino ◽  
Joseph Bowles ◽  
Flavien Hirsch ◽  
Nicolas Brunner
Keyword(s):  
Quantum Measurements ◽  
Variable Model ◽  
Hidden Variable ◽  
Local Hidden Variable

scholarly journals Quantum theory cannot violate a causal inequality

2021 ◽  
Author(s):  
Tom Purves ◽  
Anthony Short
Keyword(s):  
Quantum Theory ◽  
Causal Model ◽  
Bell Inequality ◽  
Variable Model ◽  
Hidden Variable ◽  
Non Locality ◽  
Local Hidden Variable

Abstract Within quantum theory, we can create superpositions of different causal orders of events, and observe interference between them. This raises the question of whether quantum theory can produce results that would be impossible to replicate with any classical causal model, thereby violating a causal inequality. This would be a temporal analogue of Bell inequality violation, which proves that no local hidden variable model can replicate quantum results. However, unlike the case of non-locality, we show that quantum experiments can be simulated by a classical causal model, and therefore cannot violate a causal inequality.

scholarly journals A local hidden variable theory for the GHZ experiment

2002 ◽  
Vol 295 (5-6) ◽  
pp. 229-240 ◽  
Author(s):  
László E. Szabó ◽  
Arthur Fine
Keyword(s):  
Variable Theory ◽  
Hidden Variable ◽  
Ghz Experiment ◽  
Local Hidden Variable

scholarly journals QUANTUM TELEPORTATION WITH PAIR-COHERENT STATES

2007 ◽  
Vol 05 (01n02) ◽  
pp. 17-22 ◽  
Author(s):  
AURÉL GÁBRIS ◽  
GIRISH S. AGARWAL
Keyword(s):  
Coherent State ◽  
Quantum Teleportation ◽  
Coherent States ◽  
Continuous Variable ◽  
Quantum Mechanical ◽  
Variable Theory ◽  
Hidden Variable ◽  
Mechanical Explanation ◽  
Pair Coherent State ◽  
Local Hidden Variable

Recently, it has been argued that all presently performed continuous variable quantum teleportation experiments could be explained using a local hidden variable theory. In this paper, we study a modification of the original protocol which requires a fully quantum mechanical explanation even when coherent states are teleported. Our calculations of the fidelity of teleportation using a pair-coherent state under ideal conditions suggest that fidelity above the required limit of 1/2 may be achievable in an experiment also.

Sign in / Sign up

Export Citation Format

Share Document