UNSW researchers at the Centre of Excellence for Quantum Computation and Communication Technology (CQC2T) have shown for the first time that they can build atomic precision qubits in a 3-D device—another major step towards a universal quantum computer.
The team of researchers, led by 2018 Australian of the Year and Director of CQC2T Professor Michelle Simmons, have demonstrated that they can extend their atomic qubit fabrication technique to multiple layers of a silicon crystal—achieving a critical component of the 3-D chip architecture that they introduced to the world in 2015. This new research was published today in Nature Nanotechnology.\
The group is the first to demonstrate the feasibility of an architecture that uses atomic-scale qubits aligned to control lines—which are essentially very narrow wires—inside a 3-D design.
What's more, the team was able to align the different layers in their 3-D device with nanometer precision—and showed they could read out qubit states single shot, i.e. within one single measurement, with very high fidelity.
"This 3-D device architecture is a significant advancement for atomic qubits in silicon," says Professor 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 3-D 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. Withthisresult we have now shown that engineering our approach in 3-D is possible in the way we envisioned it a few years ago."