Resource-efficient energy test and parameter estimation in continuous-variable quantum key distribution

TL;DR

This paper enhances the efficiency of energy testing and parameter estimation in continuous-variable quantum key distribution by leveraging symmetry, enabling better resource use and higher key rates in practical quantum communication.

Contribution

It introduces methods to improve energy test and parameter estimation routines in CV QKD, making them more resource-efficient and practical.

Findings

Improved energy test efficiency increases key rate.

Resource-efficient parameter estimation in MDI QKD.

All raw data can be used for key and routine processes.

Abstract

Symmetry plays a fundamental role in the security analysis of quantum key distribution (QKD). Here we review how symmetry is exploited in continuous-variable (CV) QKD to prove the optimality of Gaussian attacks in the finite-size regime. We then apply these results to improve the efficiency, and thus the key rate, of these protocols. First we show how to improve the efficiency of the energy test, which is one important routine in a CV QKD protocol aimed at establishing an upper bound on the effective dimensions of the otherwise infinite-dimensional Hilbert space of CV systems. Second, we show how the routine of parameter estimation can be made resource efficient in measurement-device independent (MDI) QKD. These results show that all the raw data can be used both for key extraction and for the routines of energy test and parameter estimation.