Experimental Passive Decoy-State Quantum Key Distribution

TL;DR

This paper experimentally demonstrates a passive decoy-state quantum key distribution over 50 km fiber, showing it as a practical and secure method with a key rate of 100 bits/sec, reducing side channel risks.

Contribution

It introduces and experimentally validates a passive decoy-state QKD method using built-in decoy states with low dark count detectors, enhancing security and practicality.

Findings

Successfully demonstrated over 50 km fiber

Achieved a key rate of about 100 bits/sec

Reduced side channel information leakage

Abstract

The decoy-state method is widely used in practical quantum key distribution systems to replace ideal single photon sources with realistic light sources by varying intensities. Instead of active modulation, the passive decoy-state method employs built-in decoy states in a parametric down-conversion photon source, which can decrease the side channel information leakage in decoy state preparation and hence increase the security. By employing low dark count up-conversion single photon detectors, we have experimentally demonstrated the passive decoy-state method over a 50-km-long optical fiber and have obtained a key rate of about 100 bit/s. Our result suggests that the passive decoy-state source is a practical candidate for future quantum communication implementation.