Research collaboration between UNSW and the University of Sydney has overcome a fundamental hurdle to building quantum computers in silicon, opening the way to further develop the machines at scale.

The two groups, led by Professor David Reilly at the University of Sydney and Professor Andrew Dzurak at UNSW, have demonstrated that the state, or value, of a quantum bit (qubit) in silicon can be read out in a way that removes the need to have readout sensors alongside the qubits.

Underpinning this research is the support of ANFF-NSW, where almost the entire fabrication process for these devices took place. The researchers were able to work with a batch of a few hundred template qubit devices, fabricated by the ANFF team at UNSW using a variety of thermal deposition, photolithography, and silicon etching.

Then, Anderson West, a PhD student working with Professor Dzurak and lead author of the research, further built on these stock devices using ANFF-NSW’s electron beam lithography capabilities to create features that were spaced ~30nm apart, atomic layer deposition to lay down nanometre-thick layers of aluminium oxide, in combination with the associated lift-off stages to remove unwanted material and create an intricate pattern of metal that enables the device to work.

The result is published in Nature Nanotechnology.

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