Detector-decoy quantum key distribution without monitoring signal disturbance

TL;DR

This paper introduces a practical quantum key distribution protocol that uses the detector-decoy method with threshold detectors, eliminating the need for photon number resolving detectors while maintaining security and high noise tolerance.

Contribution

It presents a novel application of the detector-decoy method to round-robin differential phase-shift QKD, enabling secure implementation with simpler threshold detectors.

Findings

Protocol achieves secure key distribution without photon number resolving detectors

Provides bounds on detected single-photon events using the detector-decoy method

Maintains high noise tolerance suitable for practical quantum communication

Abstract

The round-robin differential phase-shift quantum key distribution protocol provides a secure way to exchange private information without monitoring conventional disturbances and still maintains a high tolerance of noise, making it desirable for practical implementations of quantum key distribution. However, photon number resolving detectors are required to ensure that the detected signals are single photons in the original protocol. Here, we adopt the detector-decoy method and give the bounds to the fraction of detected events from single photons. Utilizing the advantages of the protocol, we provide a practical method of performing the protocol with desirable performances requiring only threshold single-photon detectors.