Experimental quantum key distribution with finite-key security analysis for noisy channels

TL;DR

This paper demonstrates experimentally that secure quantum keys can be generated in noisy channels with finite-key analysis, making quantum cryptography feasible in practical, time-constrained scenarios like satellite communications.

Contribution

It provides the first experimental validation of finite-key security bounds in noisy quantum channels, optimizing prepare-and-measure schemes for real-world conditions.

Findings

Secure keys can be extracted under various channel conditions.

Finite-key bounds determine the required number of qubits for security.

Effective quantum cryptography is feasible in practical, limited-time scenarios.

Abstract

In quantum key distribution implementations, each session is typically chosen long enough so that the secret key rate approaches its asymptotic limit. However, this choice may be constrained by the physical scenario, as in the perspective use with satellites, where the passage of one terminal over the other is restricted to a few minutes. Here we demonstrate experimentally the extraction of secure keys leveraging an optimal design of the prepare-and-measure scheme, according to recent finite-key theoretical tight-bounds. The experiment is performed in different channel conditions, and assuming two distinct attack models: individual attacks, or general quantum attacks. The request on the number of exchanged qubits is then obtained as a function of the key size and of the ambient quantum bit error rate. The results indicate that viable conditions for effective symmetric, and even one-time-pad, cryptography are achievable.