Secure Key Rate of the BB84 Protocol using Finite Sample Bits

TL;DR

This paper enhances the finite-key analysis of the BB84 quantum key distribution protocol by developing tighter confidence intervals for phase error rates and demonstrating improved key rates through accurate channel estimation.

Contribution

It introduces methods for constructing tighter confidence intervals and shows that accurate channel estimation increases key rates non-asymptotically.

Findings

Tighter conservative confidence intervals improve key rate estimates.

Accurate channel estimation enhances key rates over amplitude damping channels.

Non-asymptotic analysis confirms increased key rates with proposed methods.

Abstract

We improve the non-asymptotic key rate shown by Scarani and Renner by proposing several methods to construct tighter conservative confidence intervals of the phase error rate than one shown by them. In addition, we show that the accurate channel estimation method non-asymptotically increases the key rate over the amplitude damping channel as well as the asymptotic case in the BB84 protocol.