CHSH Bell tests for optical hybrid entanglement

Optical hybrid entanglement can be created between two qubits, one encoded in a single photon and another one in coherent states with opposite phases. It opens the path to a variety of quantum technologies, such as heterogeneous quantum networks, merging continuous- and discrete-variable encoding, a...

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Bibliographic Details
Published in:New journal of physics 2024-03, Vol.26 (3), p.33019
Main Authors: Moradi, Morteza, Camilo López Carreño, Juan, Buraczewski, Adam, McDermott, Thomas, Elisabeth Asenbeck, Beate, Laurat, Julien, Stobińska, Magdalena
Format: Article
Language:English
Subjects:
Bell inequalities
Bell's inequality
Continuity (mathematics)
Efficiency
entanglement testing
hybrid quantum entanglement
Informatics
Parity
Photons
Physics
Quantum entanglement
quantum information
quantum optics
Quantum Physics
Quantum theory
Qubits (quantum computing)
Tomography
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Summary:Optical hybrid entanglement can be created between two qubits, one encoded in a single photon and another one in coherent states with opposite phases. It opens the path to a variety of quantum technologies, such as heterogeneous quantum networks, merging continuous- and discrete-variable encoding, and enabling the transport and interconversion of information. However, reliable characterization of the non-local nature of this quantum state is limited so far to full quantum state tomography. Here, we perform a thorough study of Clauser–Horne–Shimony–Holt Bell inequality tests, enabling practical verification of quantum nonlocality for optical hybrid entanglement. We show that a practical violation of this inequality is possible with simple photon number on/off measurements if detection efficiencies stay above 82%. Another approach, based on photon-number parity measurements, requires 94% efficiency but works well in the limit of higher photon populations. Both tests use no postselection of the measurement outcomes and they are free of the fair-sampling hypothesis. Our proposal paves the way to performing loophole-free tests using feasible experimental tasks such as coherent state interference and photon counting.
ISSN:1367-2630
1367-2630
DOI:10.1088/1367-2630/ad2d40