Quantum Technology New Alloy Cools Quantum Chips Without Helium-3

Quantum computers need to be colder than outer space. Only just above absolute zero can qubits maintain their fragile quantum state. Until now, helium-3, a rare and expensive isotope, has been necessary for this purpose. Chinese scientists now claim to have found an alternative.

A team of researchers from the Institute of Theoretical Physics and the Institute of Physical Sciences in Hefei, both under the umbrella of the Chinese Academy of Sciences (CAS), and Jiao Tong University in Shanghai has found a material and a method that enables quantum cooling without helium-3, writes CAS on its website.

Cooling Module Reaches Minus 273 Degrees Celsius

The compound of europium, cobalt, and aluminum is represented by the formula EuCo₂Al₉, abbreviated as ECA. A cooling module built with it has reached a temperature of 106 millikelvin, reports the South China Morning Post. That's minus 273 degrees Celsius (−459 °F), just above absolute zero—a record. In a paper published in the journal Nature on February 11, the Chinese researchers described their rare-earth alloy in more detail.

One of the most important properties of the new material is its ability to transfer its temperature to its surroundings. "At such extreme temperatures, the thermal conductivity of ECA is one to two orders of magnitude higher than that of conventional magnetic refrigerants. This overcomes the critical bottleneck in extracting cooling power," writes the Chinese Academy of Sciences in Beijing.

Up to a million tons of helium-3 are believed to be stored on the Moon, which partly explains the interest of spacefaring nations in the Earth's satellite.

Helium-3 Rare and Expensive

Until now, helium-3 was the only way to achieve such temperatures. The rare isotope is the refrigerant in so-called dilution refrigerators, those room-sized cooling devices used to operate quantum chips today. The global annual production is only 15,000 to 20,000 liters, mainly as a byproduct of nuclear weapon maintenance. Every kilogram costs a great deal of money. Up to a million tons of helium-3 are believed to be stored on the Moon, which partly explains the interest of spacefaring nations in the Earth's satellite.

Novelty from China

Researchers Develop Supercomputer in Refrigerator Format

How Adiabatic Demagnetization Refrigeration Works

The cooling principle behind this is called adiabatic demagnetization refrigeration (ADR). A magnetic material is exposed to a strong magnetic field, forcing its internal magnetic moments to align in one direction. Heat is released and dissipated in this process.

When the material is then thermally isolated from the cooling bath and the field is turned off, the magnetic moments return to their disordered state. Since no external heat can flow during this adiabatic process, thermal energy is extracted from the material itself, causing it to cool significantly. Although previous materials could bring themselves to extreme temperatures, they could not transfer the cold to surrounding components. A refrigerator that only cools itself is of little use.

Advantages and Potentials of ECA

According to Chinese researchers, ECA is one of the few known "metallic spin super-solids." It conducts heat as well as an ordinary metal, even near absolute zero.

In practice, this could lead to the construction of compact, portable cooling modules without moving parts. No wear and tear, no vibrations. IBM's Goldeneye, one of the largest dilution refrigerators in the world, costs several million euros and weighs almost seven tons. An ADR module based on ECA, on the other hand, could fit into a control cabinet, according to Chinese reports on the invention.

The cooling module could provide quantum chips with a stable, portable cooling source and also support space research projects.

Advancing Quantum Technology

"The alloy has the potential for mass production. The team recently developed a pure metal cooling module based on this material," writes the Academy on its website. The cooling module could provide quantum chips with a stable, portable cooling source and also "support space research projects with an autonomous cooling system," it states. In addition to quantum research, ultra-sensitive measuring devices in other areas and military electronics are considered potential application fields.

Chinese Research a Step Ahead

The technology magazine Tom's Hardware reports on an interesting temporal coincidence. "On January 27, the U.S. Defense Advanced Research Projects Agency (DARPA) issued a call for modular cooling systems that do not rely on helium-3 for next-generation applications in quantum research and defense," the magazine writes. "Less than two weeks later, Chinese researchers published their results, signalling that they are ahead of DARPA," reports Tom's Hardware.

Peking University already built two cooling devices based on the ADR principle in 2024, which are reportedly being used stably in quantum research since then, reports the South China Morning Post. In this year's work report of the Chinese government, quantum technology is named as a strategic development goal.