QOSST: A Highly-Modular Open Source Platform for Experimental Continuous-Variable Quantum Key Distribution

TL;DR

QOSST is an open-source, modular platform designed to simplify experimental continuous-variable quantum key distribution, achieving high secret key rates and encouraging community-driven advancements.

Contribution

This work introduces QOSST, a hardware-agnostic, highly modular open-source software platform for CV-QKD experiments, lowering barriers to entry and enabling diverse configurations.

Findings

Achieved secret key rates of several Mbit/s over metropolitan distances.

Demonstrated state-of-the-art performance with RF-heterodyne detection.

Validated software through experimental benchmarking with a local oscillator.

Abstract

Quantum Key Distribution (QKD) enables secret key exchange between two remote parties with information-theoretic security rooted in the laws of quantum physics. Encoding key information in continuous variables (CV), such as the values of quadrature components of coherent states of light, brings implementations much closer to standard optical communication systems, but this comes at the price of significant complexity in the digital signal processing techniques required for operation at low signal-to-noise ratios. In this work, we wish to lower the barriers to entry for CV-QKD experiments associated to this difficulty by providing a highly modular, open source software that is in principle hardware agnostic and can be used in multiple configurations. We benchmarked this software, called QOSST, using an experimental setup with a locally generated local oscillator, frequency multiplexed pilots and RF-heterodyne detection, and obtained state-of-the-art secret key rates of the order of Mbit/s over metropolitan distances at the asymptotic limit. We hope that QOSST can be used to stimulate further experimental advances in CV-QKD and be improved and extended by the community to achieve high performance in a wide variety of configurations.