UNSW claims demonstration of 3D atomic-scale quantum chip architecture

The 3D architecture is touted as a major step in the development of a blueprint to build a large-scale quantum computer.

Scientists from the University of New South Wales (UNSW) have announced another step in the race to develop the first quantum computer, touting the ability to build 3D atomic-scale quantum chips.

The researchers from the Centre of Excellence for Quantum Computation and Communication Technology (CQC2T) at UNSW said they have demonstrated that atomic precision qubits can be built in a 3D device by using an atomic quantum bit (qubit) fabrication technique to multiply layers of a silicon crystal.

Led by Professor Michelle Simmons, the researchers are the first to go public with the ability to demonstrate the feasibility of an architecture that uses atomic-scale qubits aligned to control lines -- which UNSW said are essentially very narrow wires -- inside a 3D design.

Additionally, the team said it is able to align the different layers in their 3D device with nanometre precision, and also showed they can read out qubit states within one single measurement -- rather than having to rely on averaging out millions of experiments -- with very high fidelity.

"This 3D device architecture is a significant advancement for atomic qubits in silicon. 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," Simmons said.

"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."

More from UNSW: UNSW has found a way to access information stored within atoms UNSW unlocks qubit signal frequency control in quantum advancement | UNSW unveils complete design of a silicon quantum computer chip | Flip-flop qubits: UNSW conceives 'radical' quantum computing design | UNSW unlocks key to quantum coding in silicon

The team also demonstrated how to build a second control plane on top of the first layer of qubits.

In simple terms, CQC2T researcher and co-author of the research that was published in Nature Nanotechnology Dr Joris Keizer explained the team built the first plane, and then optimised a technique to grow the second layer without impacting the structures in the first layer.

"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," Keizer added.

Simmons said the teams are working towards a large-scale architecture that will lead to the eventual commercialisation of the technology.

"While we are still at least a decade away from a large-scale quantum computer, the work of CQC2T remains at the forefront of innovation in this space. Concrete results such as these reaffirm our strong position internationally."


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