Practical high-dimensional quantum key distribution protocol over deployed multicore fiber

• DOI: 10.1038/s41467-024-45876-x
• Publication Date: 2024-02-23T08:02:41Z
• Authors: Mujtaba Zahidy; Domenico Ribezzo; Claudia De Lazzari; Ilaria Vagniluca; Nicola Biagi; Ronny Müller; Tommaso Occhipinti; Leif K. Oxenløwe; Michael Galili; Tetsuya Hayashi; Dajana Cassioli; Antonio Mecozzi; Cristian Antonelli; Alessandro Zavatta; Davide Bacco
• Keywords: Quantum key distribution; Multi-core processor; Key generation

Abstract Quantum key distribution (QKD) is a secure communication scheme for sharing symmetric cryptographic keys based on the laws of quantum physics, and considered player in realm cyber-security. A critical challenge QKD systems comes from fact that ever-increasing rates at which digital data are transmitted require more performing sources keys, primarily terms secret generation rate. High-dimensional path encoding has been proposed as candidate approach to address this challenge. However, while proof-of-principle demonstrations lab experiments have reported literature, realistic environments still missing. Here we report 4-dimensional hybrid time-path-encoded system over 52-km deployed multicore fiber link forming by looping back two cores 26-km 4-core optical fiber. Our results indicate robust high-dimensional can be implemented environment combining standard telecom equipment with emerging technology.