Security bound of continuous-variable quantum key distribution with noisy coherent states and channel

TL;DR

This paper analyzes the security of a continuous-variable quantum key distribution protocol using noisy coherent states and channels, proving its security against Gaussian collective attacks and deriving a lower bound for the secure key rate.

Contribution

It demonstrates the security equivalence of prepare-measurement and entanglement-based schemes and provides a lower bound for the secure key rate in noisy, lossy channels.

Findings

Protocol is secure against Gaussian collective attacks.

Prepare-measurement and entanglement-based schemes are equivalent.

A lower bound for the secure key rate is established.

Abstract

Security of a continuous-variable quantum key distribution protocol based on noisy coherent states and channel is analyzed. Assuming the noise of coherent states is induced by Fred, a neutral party relative to others, we prove that the prepare and measurement scheme and entanglement-based scheme are equivalent. Then, we show that this protocol is secure against Gaussian collective attacks even if the channel is lossy and noisy, and further, a lower bound to the secure key rate is derived.