10 GHz Robust polarization modulation towards high-speed satellite-based quantum communication

TL;DR

This paper presents a 10 GHz polarization modulation scheme for satellite quantum communication that overcomes previous speed limitations, achieving low error rates and extending transmission distances.

Contribution

It introduces a novel modulation method leveraging lithium niobate non-reciprocity to surpass 2 GHz speed limits in satellite QKD systems.

Findings

Achieved 10 GHz polarization modulation with 0.53% QBER

Extended transmission distance to over 350 km

Demonstrated robustness in high-loss, high-speed conditions

Abstract

In practical satellite-based quantum key distribution (QKD) systems, the preparation and transmission of polarization-encoding photons suffer from complex environmental effects and high channel-loss. Consequently, the hinge to enhancing the secure key rate (SKR) lies in achieving robust, low-error and high-speed polarization modulation. Although the schemes that realize self-compensation exhibit remarkable robustness. Their modulation speed is constrained to approximately 2 GHz to avoid the interaction between the electrical signal and the reverse optical pulses. Here we utilize the non-reciprocity of the lithium niobate modulators and eliminate the modulation on the reverse optical pulses. As this characteristic is widely available in the radio-frequency band, the modulation speed is no longer limited by the self-compensating optics and can be further increased. The measured average intrinsic QBER of the different polarization states at 10 GHz system repetition frequency is as low as 0.53% over 10 min without any compensation. And the experiment simulation shows that the proposed scheme extends the transmission distance to more than 350 km. Our work can be be efficient performed to the high-speed and high-loss satellite-based quantum communication scenario.