Implementation of a twin-beam state-based clock synchronization system with dispersion-free HOM feedback

Abstract

In the field of clock synchronization, the application of frequency-entangled source is a promising direction to improve accuracy and security. In this paper, we analyze the performance of the twin-beam state and the difference-beam state using a practical second-order interference-based scheme. The advantages of the twin-beam state are pointed out especially for the dispersion-free property of HOM interference in a long-distance clock transfer. With the introduction of dispersion-compensated material, our experimental system based on a twin-beam state achieves a clock accuracy at 4 ps with a time offset precision of 1.8 ps over 10 s acquisition time while the time deviation is 0.15 ps over an averaging time of 5500 s in a 22 km-long transmission. These properties exhibit a leading position compared with the current clock synchronization system using the same theoretical scheme and also competitive among the implementations using other second-order interference-based schemes.

All-fiber telecom band energy-time entangled biphoton source

“…Among them, energy-time entanglement has attracted growing attention due to its strong temporal correlation and robustness to loss and decoherence when propagating through long-distance fiber links [2] . Till now, it has been applied in numerous fiber-based quantum communication and metrology experiments including quantum clock synchronization (QCS) [3][4][5][6][7][8][9] , quantum key distribution (QKD) [10][11][12][13] , quantum nonlocality tests [14,15] , quantum microwave photonics [16] , etc. However, most of the experiments were implemented over fiber spools, implying that the above research is still at the demonstration stage.…”

A clock synchronization method based on quantum entanglement

“…As an important physical resource, quantum entanglement has been applied to quantum secure direct communication (QSDC) 1 – 6 , quantum key distribution (QKD) 7 – 17 , quantum teleportation (QT) 18 , 19 , quantum clock synchronization (QCS) 20 , 21 , renormalization of field theories 22 . It is worth noting that clock synchronization is extremely important in satellite earth quantum communications 23 .…”