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Witnessing effective entanglement in a continuous variable prepare&measure setup and application to a QKD scheme using postselection

S. Lorenz·J. Rigas·M. Heid·U. L. Andersen·N. Lütkenhaus·G. Leuchs
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Abstract

We report an experimental demonstration of effective entanglement in a prepare&measure type of quantum key distribution protocol. Coherent polarization states and heterodyne measurement to characterize the transmitted quantum states are used, thus enabling us to reconstruct directly their Q-function. By evaluating the excess noise of the states, we experimentally demonstrate that they fulfill a non-separability criterion previously presented by Rigas et al. [J. Rigas, O. Gühne, N. Lütkenhaus, Phys. Rev. A 73, 012341 (2006)]. For a restricted eavesdropping scenario we predict key rates using postselection of the heterodyne measurement results.

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S. Lorenz, J. Rigas, M. Heid, U. L. Andersen, N. Lütkenhaus, G. Leuchs. 2006-03-30. Witnessing effective entanglement in a continuous variable prepare&measure setup and application to a QKD scheme using postselection. https://doi.org/10.1103/physreva.74.042326

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