The first quantum memory of a single photon polarization state in a solid-state system by Chinese scientists

12th from Hkust, the University of Guo Guangzhan, led by the Chinese Academy of Sciences, the key laboratory of quantum information, in solid-state systems for the first time to achieve a single photon polarization state of quantum memory, refresh the world record.

Quantum memory is one of the core devices in the field of quantum information, and it is a necessary component of the basic quantum information process such as quantum teleportation and quantum dense coding. At the same time, it can solve the problem of information loss in the remote quantum communication, as well as the distributed quantum computation and quantum precision measurement.

The commonly used quantum memory, such as cold Atom, Bose-Einstein condensation and so on, has the disadvantage of narrow band and expansibility, and it is difficult to apply to practical quantum networks. In recent years, the solid state quantum memory based on rare earth ions doped crystals it has the advantages of long life, high stability, wide bandwidth and strong expansibility, but because the crystal has birefringence effect, can not light the polarization state to load information, and all kinds of polarization state is the most convenient vector of quantum information. Therefore, how to realize the photon polarization state of solid-state quantum memory is a big problem in the international academia.

The Chuanfeng group, a key laboratory of quantum information in the Chinese Academy of Sciences, uses two 1.4-mm-doped neodymium-vanadium-yttrium crystals, two orthogonal polarization states of light are dealt with, while a specially designed optical element is placed between two crystals, and the entire quantum memory is like a small "sandwich", compact and stable, extensible and integrated.

In the experiment, the "collinear" optical path used in the traditional solid-state quantum storage scheme was discarded, the cross type light path is designed so that the pumped light of pretreatment is no longer coincident with the light to be stored, thus reducing the noise caused by the pump, thereby greatly improving the fidelity of the memory, up to 99.9%, Far higher than the previous single photon polarization storage 95% of the maximum fidelity, reviewers praised as "a novel solution in solid-state devices to store the polarization bit of the important problem."

Chuanfeng, the results are of great significance to further improve the miniaturization and integration of practical quantum communication network components. At the same time, the high fidelity quantum storage can be applied to the research fields of fault-tolerant quantum computation and so on.

The results of the study, published 11th in the United States "Physical Review Letters", and by the American Physical Science website "Physics Summary" column as a highlight of the report.