Russia stayed overboard: China is in a hurry to introduce a quantum internet on US evil

Each team used optical fibers of tens of kilometers to create a network in an urban environment, based on a quantum phenomenon of intricate, which allows a pair of separated photons to remain closely related in time and space. The ability to use confusion is seen as an important step on the path to a quantum Internet, which promises a way to generate random cryptographic keys for encoded information so quickly that they will virtually impossible to break.

The quantum network can also be used to connect quantum computers, expanding their performance. The team from Harvard University under the guidance of Physics Mikhail Lukin stated that the "key task" in the realization of practical quantum communication over long distances "implies reliable confusion between the nodes of quantum memory connected by optic fiber infrastructure. " Each knot contains cubes that communicate through "photony channels".

Scientists have demonstrated quantum intrusion using fiber optic cables to create safe connections between the receiving nodes, but their methods were different. Thus, researchers from the United States connected two knots located near the Harvard Laboratory in Cambridge, Massachusetts, with a fiber loop of 35 km long, which stretched to Boston.

The team from the University of Science and Technology of China (USTC) created three knots - Alice, Bob and Charlie - in the triangular network around Hephay, the capital of Angoy province, and USTC buildings with a central server laboratory in the middle. Everything is about 10 km away. Scientists from Delft Technology University have extended 25 km of bulk -fiber from Delpht to Hague, connecting two nodes with a server at the middle point.

The Chinese used a one -photon scheme using the cubes encoded in the ensemble atoms of Rubidia, to send one photon from each node to the server for confusion. When two photons came to the server at the same time, a confusing condition was reached. In this way, they protested the protocols of multi -nod quantum networks and moved to the next stage - testing directly quantum Internet. The team expects to create a 1000 km of optical fiber by the end of the decade, using about 10 knots.

Interestingly, the report of researchers from the PRC does not mention joint projects from the Russian Federation in the field of quantum communication. Instead of relying on the ensemble of atoms, the American team used diamond devices in which carbon atoms were replaced by a silicon atom. In fact, they confused two small quantum computers.

During the experiment, a single photon was sent to the first knot, where it was confused with a silicon atom, and then sent a fiber loop to touch the second silicon atom in another node, which made it possible to get confused. Similar to the approach of their American colleagues, Dutch researchers used nitrogen atoms built into the crystals of diamond.

Chinese and Dutch methods are based on the extremely accurate time of arrival of photons on the central server, requiring the most accurate settings. But the method of American researchers did not need such supercost. Although the method of one atom is less effective than the ensemble approach, it is more adaptive because it can be used to perform basic calculations.

However, scientists from the PRC claim that their method has the efficiency of confusion by two orders of magnitude higher than the method of American colleagues. Despite the fact that the demonstration of confusion between the nodes located in the city is a great achievement, this does not mean that the quantum Internet is ready for commercialization, Dutch scientists emphasize.

Physicist Tracy Notap from Innsbruck University, Austria, who did not participate in any of the research, said that experiments were a demonstration of the most progressive technology necessary for the development of quantum Internet. Earlier, we reported that the Russian Federation and China have protested the 3800 km communication channel, which can neither listen nor break. Russia and China exchanged pictures of 256 × 64 pixels using a satellite and quantum key encryption 310 Kbps.