Researchers in Shanghai say they have developed a device to create extremely low temperatures that would make cutting-edge technology such as quantum computers more widely available.
The core components of most quantum machines – from computers to satellites – detect and manipulate subatomic particles that are easily disturbed by heat so must operate in conditions near absolute zero.
Cooling the most advanced quantum hardware requires helium-3, an isotope of helium that can carry heat away with unmatched efficiency.
But helium-3 is extremely rare on Earth and the main supply is from ageing nuclear warheads.
The demand for helium-3 in quantum research and other disruptive technology has soared.
In less than two decades its price has risen more than 40-fold to over US$5,000 per litre in gas form.
But even then not just anybody can buy it. In the United States, for instance, helium-3 is one of the few commodities that are subject to strict government production and distribution controls on military grounds.
In a paper published in domestic peer-reviewed Science Bulletin on Wednesday, Professor Dang Haizheng and his colleagues with the Shanghai Institute of Technical Physics at the Chinese Academy of Sciences, said they had built a powerful chiller for some of the most demanding quantum machines without using any helium-3 at all.
The new cooling device uses helium-4, another helium isotope as its coolant.
Helium-4, the gas that goes into party balloons, is much more plentiful than helium-3 but is less effective as a cooling agent in extreme conditions.
When approaching temperatures as low as 2 kelvin (-271 degrees Celsius), helium-4 turns into a superfluid, climbing walls regardless of gravity and becoming much more difficult to control.
Dang’s team developed a theoretical model that could, to some extent, predict the behaviour of helium-4 flow in a superfluid state.
The chiller they built works in principle similar to a household fridge but has few moving parts. It is driven by a pulse energy source and operates at a high frequency to increase heat-transfer efficiency.
To tame the helium-4’s erratic behaviour, the chiller has a special component to stop the antigravity climb.
Part of the device must also be built with extremely high-quality components with precision twice as high as mainstream products today, according to the researchers.
In their experiment, the new cooling device kept a superconducting nanowire single-photon detector, an optical sensor commonly used in quantum machines, at a temperature of 1.8 kelvin for more than two weeks (15 days).
The results suggested that the helium-4 had the potential to completely replace helium-3 even in some most demanding applications such as space missions, said the researchers.
