Germanium superconductor could help build reliable quantum computers

A superconductor made from germanium, a material commonly used to make computer chips, could one day create more advanced and reliable quantum computers.

Superconductors are materials that conduct electricity without resistance, which is useful in making any electrical devices. They also maintain quantum coherencewhich is useful if you are trying to create a useful quantum computer.

But for now previous superconductors were typically unusual materials that would not be easy to incorporate into computer chips, Peter Jacobson from the University of Queensland, Australia, and his colleagues created one from germanium, which is already widely used in the computer industry.

The researchers created their superconductor by impregnating a film of germanium with gallium, a process known as doping. Previous research in this direction showed that this combination eventually became unstable. To avoid this, the team used X-rays to introduce more gallium into the material and thus create uniform and stable patterns.

However, like other known superconductors, this new material does not work at room temperature. It must be cooled to 3.5 Kelvin (-270°C/-453°F).

David Cardwell The University of Cambridge says the superconductor's need for extremely low temperatures precludes its use in consumer devices, but it could be ideal for quantum computing, which also typically requires supercooling.

“This could change quantum technology,” Cardwell says. “It gives a whole new level of functionality because you have a very cold environment anyway. I think that would be an obvious starting point.”

Jacobson says previous work that placed superconductors on top of semiconductors, a key component of computing devices, caused defects in the crystal structure that caused problems in applications. “Disorder is actually a parasitic effect in quantum technology,” he says. “This causes absorption of your signals.”

But the new material allows layers of gallium-doped germanium and layers of silicon to stack on top of each other with a uniform crystal structure, potentially allowing for the production of chips that combine the best properties of semiconductors and superconductors.