### Secure Coherent-state Quantum Key Distribution Protocols with Efficient Reconciliation

Authors: G. Van Assche, S. Iblisdir, N. J. Cerf

Comments: REVTeX, 11 pages, 2 figures

We study the equivalence between a realistic quantum key distribution protocol using coherent states and homodyne detection and a formal entanglement purification protocol. Maximally-entangled qubit pairs that one can extract in the formal protocol correspond to secret key bits in the realistic protocol. More specifically, we define a qubit encoding scheme that allows the formal protocol to produce more than one entangled qubit pair per coherent state, or equivalently for the realistic protocol, more than one secret key bit. The entanglement parameters are estimated using quantum tomography. We analyze the properties of the encoding scheme and investigate its application to the important case of the attenuation channel.

http://uk.arxiv.org/abs/quant-ph/0410031

## 1 Comments:

It took for a while to realise what was the work they did. It looks that they estabilished equivalence between the reconciliation and the purification protocol for the coherent state key distribution scheme. Problem in this study is for me that it is not clear whether there exist any original progress or not. Hard to evaluate.... Hummm.

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