Scientists from China have developed a new cooling technology based on a rare-earth alloy that can reach temperatures close to absolute zero without relying on helium-3, reports South China Morning Post. Such an alloy could enable compact, helium-3-free cooling systems for superconducting quantum chips, advanced electronics used by military equipment, and space applications.
The team built a compact, solid-state refrigeration module with no moving parts that reached 106 millikelvin (mK), which is -273°C, a temperature typically achieved using liquid helium. The cooling module relied on a rare-earth compound consisting of europium, cobalt, and aluminum (EuCo₂Al₉, ECA), which features thermal conductivity comparable to metals, but which can also cool itself and other components efficiently using adiabatic demagnetization (ADR), the method that does all the magic behind the discovery.
The idea behind ADR is relatively straightforward: a magnetic material is placed in a magnetic field, which forces its tiny internal magnetic moments (a tiny magnetic dipole associated with an atom or electron) to align and release heat. Then, once the system is isolated, the magnetic field is removed, the moments fall back into a disordered state, absorb heat, and reduce temperature. Because this method relies on solid materials instead of helium-3, it avoids the need for that scarce isotope, which is essential for traditional sub-kelvin cooling systems. However, there is a catch.
Historically, ADR has had a major weakness: the materials used could get cold themselves, but they were not very good at transferring that cold to other components. This limited their usefulness in real systems. Meanwhile, the EuCo₂Al₉ compound developed by the team of scientists does just that: it can cool itself and other components, making helium-3-free cooling systems capable of cooling components to nearly absolute zero temperatures possible.
In practical terms, the compact and lightweight nature of the new cooling module may enable more portable cryogenic systems, which could be valuable for quantum computers, which are about to become the next frontier of international rivalry. A compact cryogenic cooling system could enable highly scalable quantum computing platforms with performance not achievable today.
The Chinese Academy of Sciences reportedly stated that the alloy has potential for mass production and that a pure-metal refrigeration module based on this material has already been successfully demonstrated.
The development comes amid growing interest in helium-3 alternatives. On January 27, the U.S. Defense Advanced Research Projects Agency (DARPA) issued a call for modular refrigeration systems that do not rely on helium-3 for next-generation quantum and defense applications. Less than two weeks later, Chinese researchers published their results, signalling that they are ahead of DARPA.
