A 24 km fiber-based discretely signaled continuous variable quantum key distribution system

TL;DR

This paper presents a fiber-based continuous variable quantum key distribution system achieving a secure key rate of 3.45 kb/sec over 24 km, utilizing discrete signaling, post-selection, and advanced noise suppression techniques.

Contribution

It introduces a novel implementation of CV-QKD with discrete signaling and polarization multiplexing, enhancing transmission distance and security quantification.

Findings

Secure key rate of 3.45 kb/sec over 24.2 km fiber

Noise suppression of more than 27 dB from guided acoustic wave Brillouin scattering

Use of quantum state tomography for security assessment

Abstract

We report a continuous variable key distribution system that achieves a final secure key rate of 3.45 kb/sec over a distance of 24.2 km of optical fiber. The protocol uses discrete signaling and post-selection to improve reconciliation speed and quantifies security by means of quantum state tomography. Polarization multiplexing and a frequency translation scheme permit transmission of a continuous wave local oscillator and suppression of noise from guided acoustic wave Brillouin scattering by more than 27 dB.