Figure LB-1: Experimental scheme diagram [IMAGE: CAS]

A Chinese research team has realized entanglement of two quantum memories by fiber over 50 km, a breakthrough in the field of quantum communication.

Quantum entanglement is a quantum mechanical phenomenon in which the quantum states of two or more objects are described with reference to each other, even though the individual objects may be spatially separated.

The successful experiment has laid the foundation for the development of a quantum internet that should enable a number of revolutionary applications such as distributed quantum computing.

The experiment was jointly conducted by researchers with the University of Science and Technology of China (USTC), the Jinan Institute of Quantum Technology, and the Shanghai Institute of Microsystem and Information Technology of the Chinese Academy of Sciences.

The USTC researchers involved in the experiment included Pan Jianwei, often dubbed the "Father of Quantum" in China, Bao Xiaohui, and Zhang Qiang.

"Despite enormous progress, at present the maximal physical separation achieved between two nodes is 1.3 km, and challenges for longer distances remain," the researchers wrote in a paper published on February 12 in the journal Nature. "Our experiment could be extended to nodes physically separated by similar distances, which would thus form a functional segment of the atomic quantum network, paving the way towards establishing atomic entanglement over many nodes and over much longer distances."

The researchers succeeded in the experiment by using cavity enhancement to efficiently create atom-photon entanglement and quantum frequency conversion to shift the atomic wavelength to telecommunication wavelengths, according to the paper.

"These are certainly outstanding results, and steps forward for the work that needs to be carried out to implement quantum repeaters," said a reviewer of Nature of the research results. "Bringing the operation of these systems to metropolitan distances is a major advance in the field."

Source: Xinhua