(MENAFN- Asia Times) China is going to produce its own dilution refrigerators to chill superconducting chips in quantum computers, aiming to reduce its reliance on foreign cryogenic devices.
Earlier this year, two physical scientists at Anhui University developed a dilution fridge that can create and maintain an absolute zero environment at as low as 8.5 milli-Kelvin (mK), meeting the international standard that Western firms have achieved.
The two scientists are Shan Lei, a professor at Anhui University's institutes of physical science and information technology, and Wang Shaoliang, a cryogenic engineer at the same university.
On Tuesday, the duo secured seed funding from the state-owned Hefei Technology and Innovation Group to start a project that aims at commercializing their fridge from a base in the Hefei High Technology Development Zone. They said that, if the project succeeds, China will no longer have to import dilution fridges from overseas.
Currently, major dilution fridge suppliers include the United Kingdom's Oxford Instruments, Finland's BlueFors and the United States' Lake Shore Cryotronics. Last September, IBM, which operates the world's fastest quantum computer known as Osprey, launched a super-fridge project, dubbed goldeneye , to build the world's biggest dilution fridge for cooling quantum computing experiments.
IBM is building the world's largest dilution refrigerator in a program called Goldeneye. Photo: IBM
Wang, also the president of Hefei Zhileng Low Temperature Technology Group, said his company will receive the first tranche of seed funding from the Hefei Technology and Innovation Group to begin the commercialization of its dilution fridge.
He said his company chose to move into the Hefei High-Technology Development Zone as many other quantum firms have formed an ecosystem in the area. He did not disclose a timetable for the company's development, but said his company targets becoming the top dilution fridge supplier in China.
Cryogenic technology
There are three main types of quantum computers: electron-based (superconducting), atom-based (cold atom or trapped ion) and photon-based.
Superconducting quantum computers are more common than the other two but they can only operate at absolute zero temperatures, ideally below 10mK.
Such an ultra-low temperature can be achieved by a helium dilution fridge, which creates cooling power by mixing helium-3 and helium-4 isotopes. The first dilution fridge was realized in the laboratory at Leiden University in the Netherlands in 1964, reaching as low as 0.22k .
As of now, the lowest temperature that has been achieved by dilution fridges in the laboratory is 2mK.
Proteox5mK is the most powerful dilution refrigerator for commercial use. Photo: Oxford Instruments
In October 2020, Oxford Instruments unveiled a dilution fridge called Proteox5mK, which can reach base temperatures lower than 5mK and has a cooling power of more than 850 microwatts (μW) at 100mK.
In the late 1970s, the Chinese Academy of Sciences (CAS) developed a dilution fridge that achieved a temperature as low as 34mk , Chinese media said. But it later discontinued the research
The decision was followed by the establishment of a diplomatic relationship between China and the US in 1979 and the opening of the Chinese economy in the early 1980s.
At present, all Chinese superconducting quantum computers still use foreign-made dilution fridges.
New breakthroughs
After the US-China trade war broke out in 2018, CAS restarted its research on dilution fridges.
In June 2021, the CAS Institute of Physics said its cryogen-free dilution refrigerator (CFDR) reached a base temperature of around 10.9 mK for continuous circulation and 8.6 mK for single-shot operations.
Ji Zhongqing, an associate researcher at the CAS Institute of Physics, told media that he hoped the tool could be commercialised as soon as possible, so the development of China's quantum computers would not be constrained by the West's possible sanctions.
In late March this year, Ji's team in Beijing saw its dilution fridge reach a base temperature of 7.6mK.
At the same time, Wang announced that his team's dilution fridge achieved 8.5mK with a cooling power of 435 μW at 100mK. Before that, it had already reached 9.2mK on December 31 last year.
Over the past two years, the US has in several moves banned the export of its high-end semiconductors, chip-making equipment and supercomputer parts to China and has called on its allies to follow suit. To date, it has not extended the curbs to quantum computing.
Commentators noted that, even if China can self-supply its dilution fridges, it still needs electron-beam lithography to make superconducting chips. US ally Japan remains dominant in the e-beam lithography market.
read: china's fastest yet quantum computer still way behind us
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