A scaled-up version of quantum computing edges closer with the miniaturization of a vital component, thanks to the collaborative efforts of Microsoft, Stanford University, and the University of Sydney.

Previously, the University of Sydney team developed a microwave circulator, which keeps electrical signals propagating in one direction. However, its structure was too bulky for quantum applications.

Now, the team reports the miniaturization of a circulator device by a factor of 1,000. By proving this process a success, numerous circulators can be integrated into chips, thus solving one piece of the puzzle toward building quantum computers.

"Such compact circulators could be implemented in a variety of quantum hardware platforms, irrespective of the particular quantum system used," says Alice Mahoney, lead author of the paper.

To shrink the circulator tech, the speed of light was slowed down in the material by exploiting the properties of topological insulators, a new phase of matter.

Topological isolators differ from the familiar phases of matter (solid, liquid, and gas). Their surface acts as conductors, while their internal structure takes on an insulator role. This configuration could provide the pathway needed to bridge quantum and classical systems.

To cement its importance, work dedicated to its theoretical foundations earned the 2016 Nobel Prize in Physics.

Although the miniaturized invention holds great promise for quantum systems, electronics, and nanoelectronics, there is still much work ahead until practical applications are a reality.

"It is not just about qubits, the fundamental building blocks for quantum machines. Building a large-scale quantum computer will also need a revolution in classical computing and device engineering," says Professor David Reilly, leader of the Sydney team.

The full details of the report can be found in the journal Nature Communications.