Tests show that integrated quantum chip operations are possible

Quantum computers capable of solving complex problems, such as drug design or machine learning, will require millions of integrated quantum bits (or qubits) designed to correct the inevitable errors in fragile quantum systems .

Today, a team of Australian researchers has experimented with a crucial combination of these capabilities on a silicon chip, bringing the dream of a universal quantum computer closer together.

They demonstrated an integrated qubit silicon platform that combines both a unique spin addressing capability – the ability to write information on a single spin qubit without disturbing its neighbors – and a process of "reading" of qubit that will be essential for quantum error correction. .

In addition, their new integrated design can be manufactured with the help of a well-established technology used in the existing IT industry.

The team is led by Professor Scientia Andrew Dzurak of the University of New South Wales in Sydney, Program Leader at the Center for Excellence in Quantum Computing and Communication Technology (CQC2T) and Director of the NSW node of the Australian National Manufacturing Facility.

Last year, Dzurak and his colleagues released a new chip architecture project for quantum computation using silicon silicon semiconductor (CMOS) components, the basis of all modern computer chips.

In their new study, published today in the journal Nature Communications, the team combines for the first time two fundamental quantum techniques, confirming the promise of their approach.

The Dzurak team had also previously shown that an integrated silicon qubit platform could work with single-turn addressability, ie the ability to rotate a single turn without disturbing its neighbors.

They have now shown that they could combine this with a special type of quantum reading process called Pauli spin blocking, a key requirement for the quantum error correction codes that will be needed to guarantee accuracy in the big quantum computers spin. This new combination of bit reading and control techniques is a central feature of their quantum chip design.

"We have demonstrated the ability to read Pauli spin in our silicon qubit device but, for the first time, we have also associated it with spin resonance to control spin," says Dzurak.

"This is an important milestone for us on the path to quantum error correction with spin qubits, which will be essential for any universal quantum computer."

"Quantum error correction is a prerequisite for creating quantum computing that is useful on a large scale because all qubits are fragile and you have to correct the errors as they arise," he said. stated lead author Michael Fogarty, who did the experiments as part of his work. PhD research with Professor Dzurak at UNSW.

"But it creates a significant overhead in the number of physical qubits you need to run the system," Fogarty notes.

Dzurak said: "By using silicon CMOS technology, we have the perfect platform to meet the millions of qubits we will need, and our recent results provide us with the tools to get the error correction. spin qubit in the near future. "

"This confirms once again that we are on the right track, and it also shows that the architecture we have developed at UNSW has so far shown no obstacle to development of a functional quantum computer chip. "

"And, what's more, it can be manufactured using well-established industrial processes and components."

The unique approach of CQC2T using silicon

Working in silicon is important not only because the element is cheap and abundant, but also because it has been at the heart of the global computer industry for nearly 60 years. The properties of silicon are well understood and chips containing billions of conventional transistors are systematically manufactured in large production facilities.

Three years ago, the Dzurak team published in the newspaper Nature the first demonstration of quantum logic calculations in a real silicon device with the creation of a two qubit logical gate, the central building block of a quantum computer.

"These were the first steps, the first demonstrations on how to turn this radical quantum computing concept into a practical device using components that underpin all modern computer systems," says Professor Mark Hoffman, Dean of the Engineering of the UNSW.

"Our team now has a plan to significantly scale up this evolution."

"We tested elements of this design in the lab, with very positive results, and we just need to continue to build on that – which remains a challenge, but the groundwork is already done and very encouraging.

"It will still take a lot of engineering to bring quantum computing to commercial reality, but it's clear that the work we see from this extraordinary team at CQC2T places Australia in the driver's seat." ", he added.

Other authors of the new Nature Communications are researchers from UNSW, Kok Wai Chan, Bas Hensen, Wister Huang, Tuomo Tanttu, Henry Yang, Arne Laucht, Fay Hudson and Andrea Morello, as well as Menno Veldhorst from QuTech and TU Delft, Thaddeus Ladd from HRL Laboratories and Kohei Itoh of Japan Keio University.

Commercialize the intellectual property of CQC2T

In 2017, a consortium of Australian governments, businesses and academics created the first Australian quantum computing company to commercialize CQC2T 's leading intellectual property.

Silicon Quantum Computing Pty Ltd (SQC) aims to produce a 10-bit silicon demo device by 2022, a precursor to the creation of a silicon-based quantum computer.

The work of Dzurak and his team will be one of the elements of the SQC that will concretize this ambition. Scientists and engineers at UNSW at CQC2T are developing patented parallel approaches using single-atom qubit and quantum dot qubits.

In May 2018, then-Australian Prime Minister Malcolm Turnbull and French President Emmanuel Macron announced the signing of a Memorandum of Understanding regarding a new collaboration between the SQC and the largest French organization for research and development. Office of the Atomic Energy and Alternative Energies (CEA).

The memorandum of understanding provided for the creation of a joint venture in the field of silicon-CMOS quantum computing in order to accelerate and target technology development, as well as seize opportunities for marketing, bringing together French and Australian efforts to develop a quantum computer.

The proposed Franco-Australian joint venture would bring together the UNSW-based Dzurak team and a team led by CEA's Dr. Maud Vinet, experts in advanced CMOS manufacturing technology, who recently introduced a silicon qubit manufactured center. of industrial prototyping in Grenoble.

It is estimated that quantum computing could have a significant impact on industries accounting for about 40% of the current economy in Australia.

Possible applications include software design, machine learning, logistical planning and planning, financial analysis, stock market modeling, software and hardware auditing, climate modeling, design and development. rapid drug testing as well as early detection and prevention of disease.

Explore further:
Quantum Accord: Scientists Unlock Frequency Control of Precision Signals of Atomic Qubits

More information:
M. A. Fogarty et al., Integrated platform with silicon qubits with lattice addressing, exchange control and simple triplet-singlet readout, Nature Communications (2018). DOI: 10.1038 / s41467-018-06039-x