New QKD scheme for satellite-based Quantum-Secure Time Transfer

Figure outlining the researchers’ experimental setup. Credit: Dai et al.

Researchers at the University of Science and Technology of China have recently introduced a new satellite-based Quantum-Secure Time Transfer (QSTT) protocol that could enable more secure communications between different satellites or other technology in space.

Their protocol is based on two-way Quantum Key Distribution (QKD) in free space, a technique to encrypt communications between different devices.

The team demonstrated their QSTT protocol by applying it to the Micius quantum satellite. The Micius, named after ancient Chinese philosopher Micius Mozi, is the world’s first satellite capable of quantum communications, which was launched into space back in August 2016.

They performed a satellite-to-ground time synchronization using single-photon-level signals and achieved a quantum bit error rate of less than 1%, a time data rate of 9 kHz and a time-transfer precision of 30 ps.

This team of researchers is the first to demonstrate satellite based QSTT using single photons. Remarkably, the time precision achieved by their proposed protocol is comparable to that of T2L2, a state-of-the-art technique to achieve time transfer that was applied on the Jason-2 satellite, which is based on the use of strong classical laser pulses. (

The study has been published in Nature Physics.

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