UNSW scientists have developed a new single atom technology for building 3D silicon quantum chips.
UNSW’s 3D architecture is a major step in the development of a blueprint to build a large-scale quantum computer.
For the record, the team has shown for the first time that they can build atomic precision qubits in a 3D device – with precise interlayer alignment and highly accurate measurement of spin states.
What’s more, the researchers were able to align the different layers in their 3D device with nanometer precision – and showed they could read out qubit states within one single measurement, with very high fidelity.
“This 3D device architecture is a significant advancement for atomic qubits in silicon,” says UNSW professor Michelle Simmons. “To be able to constantly correct for errors in quantum calculations – an important milestone in our field – you have to be able to control many qubits in parallel.”
“The only way to do this is to use a 3D architecture, so in 2015 we developed and patented a vertical crisscross architecture. However, there were still a series of challenges related to the fabrication of this multi-layered device. With this result we have now shown that engineering our approach in 3D is possible in the way we envisioned it a few years ago.”
The team also demonstrated how to build a second control plane or layer on top of the first layer of qubits.
“It’s a highly complicated process, but in very simple terms, we built the first plane, and then optimised a technique to grow the second layer without impacting the structures in first layer,” explains researcher and co-author, Dr Joris Keizer.
“In the past, critics would say that that’s not possible because the surface of the second layer gets very rough, and you wouldn’t be able to use our precision technique anymore – however, in this paper, we have shown that we can do it, contrary to expectations.”
Image and content: University of New South Wales (UNSW)