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A project led by the University of Melbourne's Dr. Manjith Bose and Professor Jeff McCallum, who are also members of the ARC Center of Excellence for Quantum Computation and Communication Technology, has identified a promising class of superconductors that may potentially avoid the need for high levels of cryogenic cooling. These advanced materials can be manufactured, be integrable and be compatible using standard silicon and superconducting electronics approaches.

To optimize the growth of these silicide superconductors, Dr. Bose and Prof. McCallum are making extensive use of high-temperature neutron reflectometry on the Spatz reflectometer at ANSTO's Australian Center for Neutron Scattering.

Neutrons are an ideal tool for exploring extreme sample environments, such as the high pressure, temperatures or fields that are present when manufacturing circuit elements. This is because neutrons can penetrate through most common metals, allowing one to see reflective thin films deep inside furnaces, magnets and cryo-chambers.

"We were able to observe the growth rate on the nanometer-per-minute time scales at high temperatures of 800°C," Dr. Bose explained. Subsequently we were able to deploy cryogenic magnetometry measurements at ANSTO down to 3 K to detect superconducting properties."

Some of the initial work was recently in Applied Surface Science.

The work was made possible by collaboration with ANSTO scientists Dr. Anton Le Brun and Dr. David Cortie, the team who previously achieved what is believed to be for the highest temperature neutron reflectometry in 2024.

Dr. Le Brun commissioned and designed the Spatz reflectometer, which was transferred to ANSTO from Helmholtz Zentrum Berlin (HZB). Dr. Cortie established a high-temperature furnace capability on Spatz, working with the sample environment team at the Center. He also performed the low temperature cryogenic measurements, which involved working at both extremes of the temperature scale.

"While ANSTO has dilution refrigerators that go to about 20 mK to enable work on quantum material, the great thing is we didn't even need them for this study," explained Dr. Cortie. "The material developed at Melbourne University operates to about 16 K, so I was able to use a standard commercial cryo to measure the susceptibility, which was much easier."

The team also involved long-term neutron expert Emeritus Professor Trevor Finlayson, the recipient of the lifetime award of ANBUG Career Award in 2021.

"Trevor kindly provided a wealth of advice, and he had worked on similar compounds in the 1960s–1970s, albeit as bulk crystals rather than films. He provided original silicide samples from his Ph.D. thesis in 1960, which were used as some of the calibration reference standards for our superconducting measurements," explained Dr. Cortie.

"I think it speaks highly of the resilience of this family of silicide compounds. Using samples that were a half-century old also shows that true scientists never throw things away, even if our partners and family accuse us of being hoarders, because you just never know! "

The joint Melbourne-ANSTO project to perfect the growth of the superconducting layers is ongoing. The ANSTO group is also making the high-temperature thin film capability available to other university and industry groups facing similar challenges optimizing thin films and surfaces.

Quantum computers promise to revolutionize aspects of society by 2050. These tools are expected to influence every aspect of society, from how drugs are designed, your personal data security, through to how macroscale business logistics are implemented. With 2025 being the UNESCO International Year of Quantum Science and Technology, there is a widespread recognition of the untapped potential of quantum technology and computing to be unlocked in the coming century.

Among the different pathways, superconducting quantum computers have, so far, led to the largest available quantum processing units (QPUs) with 50–1,000 qubits. While encouraging, the drawbacks of these circuits are their noise, the need for error-correction and a large amount of cooling power to operate at the necessary temperatures, typically below 1 kelvin.