High-speed and high-performance polarization-based quantum key distribution system without side channel effects caused by multiple lasers

TL;DR

This paper investigates the impact of spontaneous emission on high-speed polarization-based QKD systems and demonstrates performance improvements using real-time FPGA-based temporal filtering to eliminate side channel effects.

Contribution

It is the first study to analyze spontaneous emission effects at 400 MHz and proposes a real-time FPGA filtering method to enhance system security and performance.

Findings

Spontaneous emission degrades QKD performance at high speeds.

Temporal filtering with FPGA improves key distribution quality.

Side channel effects can be effectively eliminated with proposed methods.

Abstract

Side channel effects such as temporal disparity and intensity fluctuation of photon pulses caused by random bit generation with multiple laser diodes in high-speed polarization-based BB84 quantum key distribution (QKD) systems can be eliminated by increasing DC bias current condition. However, background photons caused by the spontaneous emission process under high DC bias current degrade the performance of the QKD systems. In this study, we investigated, for the first time, the effects of spontaneously emitted photons on the system performance in a high-speed QKD system at a clock rate of 400 MHz. Also, we further show improvements of system performance without side channel effects by utilizing temporal filtering technique with real-time FPGA signal processing.