Postselection-Loophole-Free Bell Test Over an Installed Optical Fiber Network

Abstract

Device-independent (DI) quantum communication will require a loophole-free violation of Bell inequalities. In typical scenarios where line-of-sight between the communicating parties is not available, it is convenient to use energy-time entangled photons due to intrinsic robustness while propagating over optical fibers. Here we show an energy-time Clauser-Horne-Shimony-Holt Bell inequality violation with two parties separated by 3.7 km over the deployed optical fiber network belonging to the University of Concepción in Chile. Remarkably, this is the first Bell violation with spatially separated parties that is free of the post-selection loophole, which affected all previous in-field long-distance energy-time experiments. Our work takes a further step towards a fiber-based loophole-free Bell test, which is highly desired for secure quantum communication due to the widespread existing telecommunication infrastructure.

5 pages, 3 figures. Matches published version

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• Device-independent security of quantum cryptography against collective attacks
• Bell inequality violation with two remote atomic qubits
• Testing spooky action at a distance
• Loopholes in Bell Inequality Tests of Local Realism
• Phase noise measurements in long fiber interferometers for quantum repeaters applications
• Proposed Bell experiment with genuine energy-time entanglement
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Cited by in corpus (1)

• High-Visibility Time-Bin Entanglement for Testing Chained Bell Inequalities