Entanglement without hidden nonlocality

Abstract

We consider Bell tests in which the distant observers can perform local filtering before testing a Bell inequality. Notably, in this setup, certain entangled states admitting a local hidden variable model in the standard Bell scenario can nevertheless violate a Bell inequality after filtering, displaying so-called hidden nonlocality. Here we ask whether all entangled states can violate a Bell inequality after well-chosen local filtering. We answer this question in the negative by showing that there exist entangled states without hidden nonlocality. Specifically, we prove that some two-qubit Werner states still admit a local hidden variable model after any possible local filtering on a single copy of the state.

16 pages, 2 figures

References in corpus (10)

• Device-independent security of quantum cryptography against collective attacks
• Steering, Entanglement, Nonlocality, and the EPR Paradox
• Grothendieck's constant and local models for noisy entangled quantum states
• More efficient Bell inequalities for Werner states
• All bipartite entangled states display some hidden nonlocality
• Noise robustness of the nonlocality of entangled quantum states
• Einstein-Podolsky-Rosen steering and the steering ellipsoid
• Local hidden--variable models for entangled quantum states
• All quantum states useful for teleportation are nonlocal resources
• Necessary and sufficient condition for steerability of two-qubit states by the geometry of steering outcomes

Cited by in corpus (18)

• Quantum Steering
• Self-testing of quantum systems: a review
• Measurement incompatibility does not give rise to Bell violation in general
• Unbounded sequence of observers exhibiting Einstein-Podolsky-Rosen steering
• Geometry of two-qubit states with negative conditional entropy
• Measurement-device-independent entanglement and randomness estimation in quantum networks
• Algorithmic construction of local models for entangled quantum states: optimization for two-qubit states
• Activation of nonlocality in bound entanglement
• Single-copy activation of Bell nonlocality via broadcasting of quantum states
• Optimal tests of genuine multipartite nonlocality
• Measure-independent anomaly of nonlocality
• Nonlocality activation in a photonic quantum network
• Quantum Bell Nonlocality is Entanglement
• Device-independent and semi-device-independent entanglement certification in broadcast Bell scenarios
• Locally inaccessible hidden quantum correlations
• Catalytic Activation of Bell Nonlocality
• Signaling between time steps does not allow for nonlocality beyond hidden nonlocality
• Violation of Bell Monogamy Relations