Digital synchronization for continuous-variable quantum key distribution

• Published in: arXiv.org
• Main Authors: Hou-Man, Chin, Jain, Nitin, Andersen, Ulrik L, Gehring, Tobias
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 17.03.2022
• Subjects: Commercial off-the-shelf technology; Continuity (mathematics); New technology; Physics - Quantum Physics; Quantum cryptography; Synchronism
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2203.08486

Continuous variable quantum key distribution (CV-QKD) is a promising emerging technology for the distribution of secure keys for symmetric encryption. It can be readily implemented using commercial off-the-shelf optical telecommunications components. A key requirement of the CV-QKD receiver is the ability to measure the quantum states at the correct time instance and rate using the correct orthogonal observables, referred to as synchronization. We propose a digital synchronization procedure for a modern CV-QKD system with locally generated local oscillator for coherent reception. Our proposed method is modulation format independent allowing it to be used in a variety of CV-QKD systems. We experimentally investigate its performance with a Gaussian modulated CV-QKD system operating over a 10-20 km span of standard single mode fibre. Since the procedure does not require hardware modifications it paves the way for cost-effective QKD solutions that can adapt rapidly to changing environmental conditions.