Enhancing practical security of quantum key distribution with a few decoy states

TL;DR

This paper improves the security and efficiency of quantum key distribution by developing rigorous finite-statistics security proofs using only a few decoy states, supported by simulations of practical setups.

Contribution

It provides new security proofs for decoy state quantum key distribution with finite statistics and minimal decoy states, facilitating practical implementation.

Findings

Security can be rigorously guaranteed with few decoy states.

Simulations show feasible implementation with current technology.

High secret key rates are achievable with the proposed method.

Abstract

Quantum key distribution establishes a secret string of bits between two distant parties. Of concern in weak laser pulse schemes is the especially strong photon number splitting attack by an eavesdropper, but the decoy state method can detect this attack with current technology, yielding a high rate of secret bits. In this Letter, we develop rigorous security statements in the case of finite statistics with only a few decoy states, and we present the results of simulations of an experimental setup of a decoy state protocol that can be simply realized with current technology.