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arXiv · 0806.1153

Quantum Repeaters using Coherent-State Communication

Peter van Loock·Norbert Lütkenhaus·W. J. Munro·Kae Nemoto
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Abstract

We investigate quantum repeater protocols based upon atomic qubit-entanglement distribution through optical coherent-state communication. Various measurement schemes for an optical mode entangled with two spatially separated atomic qubits are considered in order to nonlocally prepare conditional two-qubit entangled states. In particular, generalized measurements for unambiguous state discrimination enable one to completely eliminate spin-flip errors in the resulting qubit states, as they would occur in a homodyne-based scheme due to the finite overlap of the optical states in phase space. As a result, by using weaker coherent states, high initial fidelities can still be achieved for larger repeater spacing, at the expense of lower entanglement generation rates. In this regime, the coherent-state-based protocols start resembling single-photon-based repeater schemes.

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Peter van Loock, Norbert Lütkenhaus, W. J. Munro, Kae Nemoto. 2008-06-06. Quantum Repeaters using Coherent-State Communication. https://doi.org/10.1103/physreva.78.062319

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