Quantum cryptography with photon-added then subtracted coherent states

What is it about?

We introduce a protocol of quantum key distribution using photon-added then subtracted coherent states, rather than coherent states. Our scheme is baed on homodyne detection (uses ordinary photomutipliers) and post-selection (simplifies reconciliation). We analyse the key rate generation under two attacks: the simultaneous quadrature measurement and the beam-splitter attack.

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Why is it important?

We show that it is possible to generate the secret key (under Eve's attacks) for longer distances compared to the coherent state based protocol. Besides, the (non-Gaussian) photon-added then subtracted coherent states may allow the use of quantum repeaters.