2024/11/21 by Lai Zhou, Jinping Lin, Zhou, Lai +25
Computer Science · Physics and Astronomy · #Applied Physics (physics.app-ph) #FOS: Physical sciences #Optics (physics.optics) #Quantum Information and Cryptography #Quantum Physics (quant-ph) #Quantum optics and atomic interactions
paper · pdf · doi:10.48550/arxiv.2411.13943
openalex publication_date 2024/11/21 · openalex created_date 2024/11/24 · openalex updated_date 2026/07/28
Owing to its repeater-like rate-loss scaling, twin-field quantum key distribution (TF-QKD) has repeatedly exhibited in laboratory its superiority for secure communication over record fiber lengths. Field trials pose a new set of challenges however, which must be addressed before the technology's roll-out into real-world. Here, we verify in field the viability of using independent optical frequency combs -- installed at sites separated by a straight-line distance of 300~km -- to achieve a versatile TF-QKD setup that has no need for optical frequency dissemination and thus enables an open and network-friendly fiber configuration. Over 546 and 603 km symmetric links, we record a finite-size secure key rate (SKR) of 0.53~bit/s and an asymptotic SKR of 0.12 bit/s, respectively. Of practical importance, the setup is demonstrated to support 44~km fiber asymmetry in the 452 km link. Our work marks an important step towards incorporation of long-haul fiber links into large quantum networks.