Quantum Entanglement Was Created For The First Time On Board A Microsatellite
Scientists are already developing the next version of such a satellite, which could exchange quantum communication signals with ground stations or other spacecraft.
On Board The CubeSat microsatellite, scientists have created pairs of entangled light particles that can be used to transmit data in secure quantum communication systems. The results of the first experiments with this device were published in the scientific journal Optica.
"Miniaturized particle entanglement systems can work well in space while consuming a minimum of energy. The success of Our SpooQy-1 device was an important step towards creating fleets of satellites that will serve the global quantum Internet," said Eitor Villard, a physicist from the National University of Singapore.
One of the main problems with modern quantum communication systems is that light gradually fades as it moves through the fiber. Therefore, when using ground-based data transmission systems, the distance between quantum network nodes is usually several hundred kilometers. A quantum communication channel over a thousand kilometers long, which was recently created in China, is rather an exception to the rule.
Physicists try to solve this problem in two ways. On the one hand, it can be circumvented by so-called quantum signal repeaters. These devices can read incoming quantum signals, amplify them, and send them to the recipient without compromising the integrity of the data.
On the other hand, it is possible to increase the transmission distance of quantum information by exchanging data via communication satellites rather than ground-based fiber-optic cables. In particular, back in September 2016, Chinese scientists led by Professor Jian-Wei pan of Shanghai University (China) launched a similar device – the Mo-Tzu orbital probe. In addition, they successfully used it for the first "Intercontinental" sessions of quantum information transmission.
The creation of a quantum Internet
The problem, as Willard points out, is that the Mo-Tzu and other devices of this kind under construction are quite large, expensive, and consume too much energy. Because of this, they cannot be quickly and massively launched into space to create a quantum network similar to the normal Internet.
Singapore physicists have been trying to solve this problem for four years, creating a set of lasers and other optical components needed to form pairs of entangled photons. When developing this system, they gave priority to compactness, as well as the ability to work in space.
The first prototype of such a system, scientists say, was successfully tested on Board the SpooQy- microsatellite. It was delivered to the ISS in April last year by a Cygnus cargo ship, and in June 2019, the satellite was launched into space. In addition to the source of entangled particles and a set of photosensors, the satellite has a communication system that scientists used to control the experiments.
As shown by subsequent observations, SpooQy-1 successfully produced pairs of entangled particles, despite the severe operating conditions and loads that its optical components experienced during the ship's takeoff and independent movements of the microsatellite in orbit around the Earth.
Now Singaporean scientists and the British Corporation RAL Space are working on creating a new version of quantum microprobes. It will be equipped with lasers and optical signal receivers that will allow the "heir " of SpooQy-1 to exchange pairs of entangled photons with ground stations or other spacecraft. The first launch of such a probe is scheduled for 2022, scientists say.