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

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.

12 pages, 12 figures, 2 tables

References in corpus (1)

• Distillation of secret key and entanglement from quantum states

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