Realistic limits on the nonlocality of an N-partite single-photon superposition

Abstract

A recent paper [L. Heaney, A. Cabello, M. F. Santos, and V. Vedral, New Journal of Physics, 13, 053054 (2011)] revealed that a single quantum symmetrically delocalized over N modes, namely a W state, effectively allows for all-versus-nothing proofs of nonlocality in the limit of large N. Ideally, this finding opens up the possibility of using the robustness of the W states while realizing the nonlocal behavior previously thought to be exclusive to the more complex class of Greenberger-Horne-Zeilinger (GHZ) states. We show that in practice, however, the slightest decoherence or inefficiency of the Bell measurements on W states will degrade any violation margin gained by scaling to higher N. The non-statistical demonstration of nonlocality is thus proved to be impossible in any realistic experiment.

6 pages, 6 figures

References in corpus (4)

• A Hybrid Long-Distance Entanglement Distribution Protocol
• Extreme nonlocality with one photon
• Robustness of Entanglement as a Resource
• Large violation of Bell inequalities using both particle and wave measurements

Cited by in corpus (6)

• Hybrid quantum information processing
• High Fidelity Teleportation of Continuous Variable Quantum States using Delocalized Single Photons
• Decoherence Effects on the Non-locality of Symmetric States
• Long Distance Nonlocality Test with Entanglement Swapping and Displacement-Based Measurements
• Algebraic and algorithmic frameworks for optimized quantum measurements
• Experimental Approach to Demonstrating Contextuality for Qudits