The entanglement of two quantum memory systems 12.5 km apart from each other

Ingrid Fadelli is a writer for the website Phys.org.

There are advantages to quantum computing technology over classical computing technology. A "quantum internet," a network that would allow quantum devices to exchange information, has been explored by some researchers.

There are many quantum technology applications that could be opened by the quantum internet. It could allow for more secure communications, more precise remote sensed and distributed quantum computing networks.

Researchers at the University of Science and Technology of China and Jinan Institute of Quantum Technology have recently demonstrated quantum entanglement between two memory devices. The development of a quantum internet could be a step closer after their paper was published.

In 2020, we published a paper in which we demonstrate the entanglement of two quantum memories via a fiber link of 50 km. The two memories we used in that experiment were located in the same lab. Making the two memories completely independent was the next step in our research.

In their experiment, the two quantum nodes were placed at a distance from each other. Their first quantum memory was entangled with a photon. The photon was sent to the second quantum memory and kept there.

The two quantum memories are entangled. Since the photon emitted from our memory is not suitable for low-loss transmission in fiber, we make use of the quantum frequency conversion technique to shift the photon's wavelength to 1342 nm instead.

Some previous studies had shown quantum connections over long distances, but they mostly involved the transfer of entangled photons. The two atom based quantum memory devices were entangled.

This could help establish reliable quantum computing networks.

The longest distance ofentanglement distribution with quantum memories was realized by us. It's the fundamental resource to build quantumentangle network and quantumrepeaters.

A recent contribution to the area of research focused on the establishment of a quantum internet was made by the group of people. It could be an important step towards enabling secure quantum communications.

The current experiment is limited by the fact that the remote entanglement generated is not heralded yet. We plan to implement a heralded version in the near future, as well as extending the number of nodes.

More information: Xi-Yu Luo et al, Postselected Entanglement between Two Atomic Ensembles Separated by 12.5 km, Physical Review Letters (2022). DOI: 10.1103/PhysRevLett.129.050503

The entangled of two quantum memories via fibres over dozens of kilometres was presented by Yong Yu and his team. There is a DOI titled " 10.1038/s41586-020- 1976-7".

Journal information: Physical Review Letters , Nature

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