Scientists in East China’s Anhui province used Micius, the world’s first quantum communication satellite, to realize long-distance quantum state transfer (QST) between two ground stations 1,200 km apart, marking a major step towards building a global quantum information processing and communication network.
The achievement was made by Pan Jianwei, a quantum physicist from the University of Science and Technology of China (USTC) in Hefei, Anhui and his team members including Peng Chengzhi, Chen Yuao and Yin Juan.
The long-distance QST by quantum teleportation is a major approach for building quantum communication networks. However, the distance and quality of quantum entanglement distribution are affected by factors such as channel loss and decoherence, and how to break the transmission distance limit has always been one of the core issues in international quantum communication research.
China launched the world’s first quantum satellite Micius in 2016, providing a new platform for human to explore long-distance quantum communication. Due to atmospheric turbulence, it is challenging to measure quantum states based on quantum interference after photons propagate in atmospheric channels.
The problem was solved as Pan's team applied optical integration bonding technology to the field of space quantum communication and developed an optical interferometer with ultra-high stability, which can keep stable for a long time without active loop closure.
Under a quantum teleportation scheme based on two-photon path-polarization mixed entangled state, the team realized the long-distance QST between the Lijiang station in Southwest China’s Yunnan province and the Delingha ground station in Northwest China’s Qinghai province, which are 1,200 km apart.
It also verified six typical quantum states during the experiment, with the fidelity of transmission all exceeding the classical limit.
The achievement has been published in the international academic journal of Physical Review Letters recently.
Pan's team set a world record ten years ago by realizing quantum teleportation over a distance of 100 km using a free-space channel in Qinghai province.