Physicists have created the first prototype of a quantum signal repeater

Physicists have created the first prototype of a quantum signal repeater. The device is based on diamond quantum memory cells, according to a study by scientists from Harvard University, published in the journal Nature.

One of the main limitations in the operation of modern quantum systems is that the light passing through the optical fiber gradually fades. Therefore, communication nodes have to be located quite close – at a distance of 200-300 km.

There are two potential solutions to this problem: the first is to abandon terrestrial fiber and transmit signals via satellite – the creation of the so-called quantum Internet. The second method involves the creation of repeaters of quantum signals – a device that reads and amplifies an incoming signal without violating data integrity.

Now, engineers for the first time managed to create a prototype of such a device. It was based on defective diamonds or SiV centers – compounds that are inclusions of nitrogen, silicon or other elements inside semiconductors.

The researchers created quantum memory cells based on SiV centers and learned how to control their behavior and speed. When cooled to absolute zero, they can store information for 0.2 milliseconds – this is enough to use quantum signals as a repeater.

“Now we are working on expanding our experiment by embedding quantum memory systems in real city fiber-optic communication channels. We plan to create a large network of entangled cells of quantum memory and test the first possible practical applications of quantum Internet”.

Ralph Reading, lead author of the study