Witnessing Trustworthy Single-Photon Entanglement with Local Homodyne Measurements

Article Article scientifique Article Witnessing Trustworthy Single-Photon Entanglement with Local Homodyne Measurements eng 2013 author Morin Olivier Jacques 503989 author Bancal Jean-Daniel 556632 author Ho Melvyn author Sekatski Pavel 679778 author D'Auria Virginia author Gisin Nicolas 23716 author Laurat Julien author Sangouard Nicolas Bruno 649865 10.1103/PhysRevLett.110.130401 0031-9007 Single-photon entangled states, i.e., states describing two optical paths sharing a single photon, constitute the simplest form of entanglement. Yet they provide a valuable resource in quantum information science. Specifically, they lie at the heart of quantum networks, as they can be used for quantum teleportation, swapped, and purified with linear optics. The main drawback of such entanglement is the difficulty in measuring it. Here, we present and experimentally test an entanglement witness allowing one to say whether a given state is path entangled and also that entanglement lies in the subspace, where the optical paths are each filled with one photon at most, i.e., refers to single-photon entanglement. It uses local homodyning only and relies on no assumption about the Hilbert space dimension of the measured system. Our work provides a simple and trustworthy method for verifying the proper functioning of future quantum networks. Dewey 500.2 35 Groupe de physique appliquée 135 false Physical review letters 110 13 d1863c65-c40e-4560-b03e-ac3ffd04fef9 Article (Published version) Public Zbinden18_morin2013a.pdf 376325 application/pdf openAccess Faculté des sciences / Section de physique / Groupe de physique appliquée

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Witnessing Trustworthy Single-Photon Entanglement with Local Homodyne Measurements	Physical review letters			2013	733	683

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Morin, Olivier Jacques