Demonstration of Femtosecond Phase Stabilization in 2 km Optical Fiber

Jun Tan, Ben Stein, Benjamin Sprenger +2 more

Huibo Hong, Runai Quan, Xiao Xiang +8 more

Fiber-optic Quantum clock synchronization has been proposed and experimentally demonstrated for its potential enhancements in precision and better guarantee of security. To further prove its advantage in practical applications, it is necessary to test its synchronization performance between clocks apart for at least intracity optical fiber distance. In this paper, we report a fiber-optic two-way quantum clock synchronization experiment with the distance reaching 50 km. With the common reference clock, a synchronization stability of 54.6 fs at 57300 s and an accuracy of 1.3 ps±36.6 ps have been achieved. With independent reference clocks, comparable performance has also been achieved combined with the microwave frequency transfer technology, which shows a stability of 89.5 fs at 57300 s. These results nicely showcase the feasibility of the two-way quantum clock synchronization to provide femtosecond-scale synchronization precision over intracity optical fiber links.

Tatsuya Tomaru

Jun-Bum Park, Sungwon Khym, Kyung-Woon Lee +2 more

We propose a unidirectional quantum key distribution (QKD) system based upon a time-division Mach–Zehnder interferometer (MZ) using phase stabilized optical fibers (PSOFs) for the sake of achieving the phase stability during the key distribution. A simple comparison between MZs constituent with PSOF and normal single mode fiber (SMF) is made. During the key distribution over 25 km of standard optical fiber, the phase drift of 4.6 × 10 -4 π/s is obtained. We discuss the demonstration of the quantum key distribution when the asymmetric MZ (AMZ) of PSOF is applied on the proposed QKD system.

Huibo Hong, Runai Quan, Xiao Xiang +8 more

The two-way quantum time transfer method has been proposed and experimentally demonstrated for its potential enhancements in precision and better guarantee of security. To further testify its advantage in practical applications, the applicable direct transmission distance as well as the achievable synchronization precision between independent time scales is of great interest. In this paper, an experiment on two-way quantum time transfer has been carried out over a 50 km long fiber link. With the common clock reference, a short-term stability of 2.6 ps at an averaging time of 7 s and a long-term stability of 54.6 fs at 57300 s were obtained. With independent clock references, assisted by microwave frequency transfer technology, the achieved synchronization showed almost equal performance and reached a stability of 89.5 fs at 57300 s. Furthermore, the spectral consistency of the utilized entangled photon pair sources has been studied concerning its effect on the transfer accuracy and long-term stability. The results obtained have promised a bright future of the two-way quantum time transfer for realizing high-precision time synchronization on metropolitan area fiber links.

Anand T. N. Kumar