Gaussian Post-selection for Continuous Variable Quantum Cryptography

TL;DR

This paper develops a security proof for continuous variable quantum key distribution using Gaussian post-selection, enabling security assessment against arbitrary attacks with improved performance over existing protocols.

Contribution

It introduces a Gaussian post-selection method that simplifies security calculations and enhances protocol performance in realistic noisy channels.

Findings

Security can be calculated using accessible quantities.

The protocol outperforms existing methods in noisy Gaussian channels.

Improvements are significant in practical regimes.

Abstract

We extend the security proof for continuous variable quantum key distribution protocols using post selection to account for arbitrary eavesdropping attacks by employing the concept of an equivalent protocol where the post-selection is implemented as a series of quantum operations including a virtual distillation. We introduce a particular `Gaussian' post selection and demonstrate that the security can be calculated using only experimentally accessible quantities. Finally we explicitly evaluate the performance for the case of a noisy Gaussian channel in the limit of unbounded key length and find improvements over all pre-existing continuous variable protocols in realistic regimes.