Space station device to aid quantum physics

By Zhao Lei | China Daily | Updated: 2017-11-29 07:09

China plans to install a cutting-edge scientific instrument on its future space station, a move likely to revolutionize research into quantum mechanics, one of the most sophisticated and complex areas of physics.

The device, called a high-accuracy time-frequency cabinet, is being developed by Chinese scientists and will be used in experiments "related to the fundamentals of physics", according to Gao Lianshan, a senior researcher of atomic clocks at the Beijing Institute of Radio Metrology and Measurement, a major participant in the program.

It will be carried by the country's first manned space station, which is expected to be assembled starting in 2019 and enter service around 2022. The 60-metric-ton station will have three parts-a core module attached to two space labs-and will operate for at least 10 years, according to space authorities.

"The cabinet will be one of the most accurate chronometers ever built by man. It will have three components-a hydrogen maser, a rubidium atomic fountain and a strontium atomic light clock. The hydrogen maser will keep operating in space, while the other two will be activated by ground control or preset programs to calibrate the hydrogen maser," Gao said in an exclusive interview, adding that the International Space Station and previous stations like Russia's Mir have had no such equipment.

The device will be tasked with performing a series of scientific experiments in the space station, including one that will enable scientists to refine their knowledge about quantum mechanics.

"Among its scientific applications, our device will act as an advanced frequency reference to measure the Rydberg constant, one of the pillars of quantum mechanics. If everything goes well, Chinese scientists will be able to use the measurement results to improve the constant," Gao said.

The Rydberg constant, named after the Swedish physicist Johannes Rydberg, is a physical constant pertaining to atomic spectra and is crucial to the research of quantum mechanics. Compared with measuring the accuracy of the constant on the ground, it is better when done in space because there is less interference, the scientist said.

Quantum mechanics, also known as quantum physics, is a physical theory that describes nature at the smallest scales of energy levels of atoms and subatomic particles. Without quantum mechanics, there would be neither modern computers and mobile phones nor the internet, and therefore the modern history of humanity would be different from what it is now.

In addition to scientific purposes, the high-accuracy time-frequency cabinet also will be used to calibrate atomic clocks used in the Beidou Navigation Satellite System, Gao said.

Atomic clocks are widely considered to be the most important apparatus used in a navigation satellite because they determine the precision of its navigation and positioning service. In addition, a lot of fields such as communication networks, electrical power grids and financial systems all depend on precision timing for synchronization and operational efficiency.

Gao's institute is part of the China Aerospace Science and Industry Corp's Second Academy and is the largest developer of atomic clocks in the country, he said, explaining that it designs and produces all three major atomic clocks-based on the hydrogen atom, cesium atom and rubidium atom-while other domestic institutes research one or two types of them.

"Some of our atomic clocks have become the world's best in terms of accuracy and stability. We are also developing the next-generation microwave mercury ion clock to prepare for future Beidou satellites," he said.

So far, 29 satellites have been launched for the Beidou network, the first in 2000 and the most recent one this month. Most have atomic clocks designed and made by Gao's institute, he said.

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