The heated race to achieve the extreme cold that quantum technologies demand may have a frontrunner. Chinese scientists have developed an alloy that almost reaches absolute zero, the coldest possible temperature, without using the scarce isotope, helium-3.
Harnessing the strange behavior of particles at the tiniest scales, quantum technologies are enabling applications that are borderline science fiction across various industries. A good example is quantum computing. Unlike conventional computers, which store information as 0s and 1s, quantum computers use qubits, fundamental units of information that can exist in multiple states simultaneously, enabling them to perform calculations that would take conventional computers millions of years to complete.
Other examples include quantum sensors that detect the tiniest changes in magnetic or gravitational fields with unprecedented precision, and quantum communication that enables virtually unhackable networks.
Now, the thing about this technology is that it “detests heat.” Atoms are constantly vibrating, giving off energy we perceive as heat. However, quantum technologies require atoms to be nearly motionless, a state achievable only at extremely low temperatures (below 1 kelvin, or -272.15 °C / -457.87 ºF).
Heat may feel abstract when we talk about temperatures close to absolute zero. However, a stray thermal vibration can scramble qubit states in quantum computing or degrade the coherence in quantum sensors. This requirement is why quantum labs mostly comprise advanced cooling technologies.
Right now, the go‑to tool for achieving the deepest chill is the dilution refrigerator, which often relies on a rare isotope, helium‑3. The system uses a carefully controlled mixture of helium‑3 and helium‑4 that can reach millikelvin temperatures, a tiny fraction of a degree above absolute zero.
The trouble is, helium‑3 is very scarce. It’s a lightweight isotope produced mainly as a by‑product of tritium decay in nuclear reactors, and global supplies are tiny compared with demand. High costs and limited availability make it a bottleneck for scaling up quantum computing and other technologies that rely on deep cryogenics.
In addition to this scarcity, helium-3 dilution refrigerators are complex and bulky, consuming significant lab space and infrastructure. These characteristics create significant barriers to making quantum technology more compact, practical, or widespread.
To overcome these barriers, researchers from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences (CAS), the Institute of Theoretical Physics of CAS, and Shanghai Jiao Tong University have developed a solid material that can reach temperatures within a whisker of absolute zero. The material, EuCo₂Al₉, is a rare‑earth alloy comprising europium, cobalt, and aluminum.
This alloy achieves cooling via adiabatic demagnetization refrigeration (ADR). In ADR, a magnetic material is exposed to a strong magnetic field. The internal magnetic moments align, releasing heat. Then, once isolated from the environment, the magnetic field is removed. When the moments disorder again, they absorb heat from the environment, dropping the temperature.
Now, adiabatic demagnetization refrigeration technology already exists. The researchers' innovation lies in the material itself. ADR materials often pose conductivity challenges. The material itself cools, but cannot extend this cooling effect outward. A good analogy would be a frozen wooden block.
The Chinese prototype alloy combines ADR’s low‑temperature potential with good thermal conductivity, forming a compact, solid‑state refrigeration module with no moving parts. It is lightweight, potentially easier to mass‑produce, and sidesteps the helium‑3 shortage entirely. In lab tests, the new material achieved around 106 millikelvin, a temperature comparable to traditional helium‑3 systems and firmly within the range needed for many cryogenic applications.
Beyond solving helium‑3 dependence, the new alloy offers additional benefits. A compact, solid‑state fridge could enable portable cryogenic systems, making quantum computing hardware more space- and cost‑efficient, and reducing the infrastructure burden on research facilities. It could accelerate the development of modular cold systems for defence, space tech, and advanced electronics.
For example, compact quantum processors could be installed directly on spaceships for deep-space computing. Similarly, secure quantum networks could be integrated into existing military infrastructure, enabling encrypted communications without requiring massive cooling facilities. Even industries such as precision sensors and advanced medical imaging could benefit from smaller, more accessible cryogenic systems.
The researchers' development couldn't be more timely. The paper covering this research was published in Nature just two weeks after the US Defense Advanced Research Projects Agency (DARPA) issued an urgent call for proposals to develop a modular, helium-3-free cooling system.
Source: Chinese Academy of Sciences
