Ultra fast quantum key distribution over a 97 km installed telecom fiber with wavelength-division multiplexing clock synchronization

TL;DR

This paper demonstrates ultra-fast quantum key distribution over 97 km of telecom fiber at 625 MHz using wavelength-division multiplexing for clock synchronization, achieving stable high-rate secure keys with low error rates.

Contribution

It introduces a practical method for high-speed QKD over long distances using WDM-based clock synchronization, enabling stable operation at 625 MHz.

Findings

Stable key generation for over an hour at 2.4 kbps

Low quantum bit error rate of 2.9%

Secure key rate of approximately 0.8 kbps

Abstract

We demonstrated ultra fast BB84 quantum key distribution (QKD) transmission at 625 MHz clock rate through a 97 km field-installed fiber using practical clock synchronization based on wavelength-division multiplexing (WDM). We succeeded in over-one-hour stable key generation at a high sifted key rate of 2.4 kbps and a low quantum bit error rate (QBER) of 2.9%. The asymptotic secure key rate was estimated to be 0.78-0.82 kbps from the transmission data with the decoy method of average photon numbers 0, 0.15, and 0.4 photons/pulse.