Squeezed-state quantum key distribution upon imperfect reconciliation

TL;DR

This paper investigates the security of continuous-variable quantum key distribution using squeezed states under realistic noisy, lossy conditions with limited reconciliation efficiency, showing limited squeezing can still ensure security.

Contribution

It demonstrates that feasible limited squeezing enhances security in Gaussian QKD over long distances with untrusted noise, considering practical imperfections.

Findings

Limited squeezing suffices for security under high noise conditions

Squeezed states minimize information leakage as described by the Holevo quantity

Security is maintained despite low reconciliation efficiency in lossy channels

Abstract

We address the security of continuous-variable quantum key distribution with squeezed states upon realistic conditions of noisy and lossy environment and limited reconciliation efficiency. Considering the generalized preparation scheme and clearly distinguishing between classical and quantum resources, we investigate the effect of finite squeezing on the tolerance of the protocol to untrusted channel noise. For a long-distance strongly attenuating channel and the consequent low reconciliation efficiency, we show that feasible limited squeezing is surprisingly sufficient to provide the security of Gaussian quantum key distribution in the presence of untrusted noise. We explain the effect by behaviour of the Holevo quantity, which describes the information leakage, and is effectively minimized by the squeezed states.