Researchers at the Center for Excellence in Quantum Computing Technology and Communication (CQC2T) researchers have shown for the first time that they can build atomic precision qubits on a 3D device – another big step toward a universal quantum computer.
The team of researchers, led by Australian 2018 and CQC2T director Michelle Simmons, demonstrated that they can extend their qubit atomic manufacturing technique to multiple layers of a silicon crystal – reaching a critical component of the 3D chip architecture that they presented to the in 2015. This new research was published today in Natural 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 – within a 3D design.
In addition, the team was able to align the different layers on their 3D device with nanoscale precision – and showed that they could read single-shot qub states, that is, within a single measurement, with very high fidelity.
"This 3D device architecture is a significant breakthrough for silicon atomic qubits," says Professor Simmons. "In order to be able to constantly correct 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 cross-architecture. However, there were still a number of challenges related to the fabrication of this multi-layer device. With this result, we now show that engineering our 3D approach is possible in the way we imagined it a few years ago. "
In this document, the team demonstrated how to build a background or control layer at the top of the first layer of qubits.
"It's a highly complicated process, but in very simple terms, we build the foreground and optimize a technique to increase the second layer without affecting the structures in the first layer," explains researcher and co-author of the CQC2T, Dr. Joris Keizer.
"In the past, critics would say that this is not possible because the surface of the second layer gets too hard, and you would not be able to use our precision technique anymore – however, in this article we show that we can do this, expectations. "
The team also demonstrated that they can align these multiple layers with nanoscale precision.
"If you write something on the first layer of silicon and then put a layer of silicon on top, you still need to identify its location to align the components in the two layers. We've shown a technique that can achieve alignment in less than 5 nanometers, which is extraordinary, "says Keizer.
Finally, the researchers were able to measure the qubit output of the 3D device with what is called a single trigger – that is, with a single precise measurement, rather than depending on the average of millions of experiments. "This will help us grow faster," says Keizer.
Professor Simmons says this research is an important milestone in the field.
"We are working systematically towards a large-scale architecture that will lead us to the eventual commercialization of the technology.
"This is an important development in the field of quantum computing, but it's also very interesting for SQC," says Professor Simmons, who is also the founder and director of SQC.
Since May 2017, Australia's first quantum computing company, Silicon Quantum Computing Pty Limited (SQC), has been working to create and commercialize a quantum computer based on a set of intellectual property developed in the CQC2T and its proprietary intellectual property.
"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 like these reaffirm our strong international position, "he concludes.