Scientists realize a compact and sensitive reading of the qubit

The research, conducted within the Simmons Group at the Center of Excellence in Quantum Computing and Communication Technology (CQC2T) with Ph.D. Prasanna Pakkiam, student as lead author, was published today. in the prestigious journal Physical examination X.

Quantum bits (or qubits) made from electrons hosted on single atoms in semiconductors are a promising platform for quantum computers on a large scale, thanks to their long-lasting stability. The creation of qubits by precisely positioning and encapsulating individual phosphorus atoms in a silicon chip is a unique Australian approach that the Simmons team leads globally.

But adding all the connections and all the doors needed to scale the architecture of the phosphorus atom was a challenge, until now.

"To even monitor a qubit, you have to create multiple connections and gates around individual atoms, where there is not much room," says Professor Simmons. "In addition, you need high quality qubits close to each other so that they can talk to each other, which is only feasible if you have the least possible gateway infrastructure. . "

Compared to other approaches for the fabrication of a quantum computer, the Simmons system already exhibited a relatively low gate density. However, the conventional measurement still required at least 4 gates per qubit: 1 to control it and 3 to read it.

By integrating the reading sensor into one of the control gates, the UNSW team was able to reduce it to just two doors: one for control and one for reading.

"Not only is our system more compact, but by integrating a superconducting circuit attached to the gate, we now have the sensitivity needed to determine the quantum state of the qubit by measuring whether an electron is moving between two neighboring atoms," says the main author Pakkiam.

"And we showed that we could do it in real time with just one measure – just one shot – without it being necessary to repeat the experience and average the results."

"This represents a major step forward in reading the information embedded in our qubits," concludes Simmons. "The result confirms that one-gate qubit reading now has the sensitivity needed to perform the quantum error correction required for an evolving quantum computer."

First Australian company of quantum computing

Since May 2017, Australia's first quantum computing company, Silicon Quantum Computing Pty Limited (SQC), has been developing and marketing a quantum computer based on a set of intellectual property rights developed by the Australian Center for Disease Control. excellence for quantum computing and communication technologies (CQC2T).

Co-located with CQC2T on the UNSW campus in Sydney, the SQC is investing in a portfolio of parallel technology development projects led by world-renowned quantum researchers, including the Australian of the year. and award-winning professor Michelle Simmons. Its goal is to produce a 10 qubit silicon demo device by 2022, the forerunner of a silicon – based quantum computer on a commercial scale.

SQC believes that quantum computing will ultimately have a significant impact on the global economy, with possible applications in software design, machine learning, logistics planning and planning, financial analysis, market modeling, software and hardware audit, climate modeling, rapid drug design, testing, and early detection and prevention of disease.

Created by a unique coalition of governments, businesses and universities, SQC competes with some of the largest multinational technology companies and foreign research laboratories.

In addition to developing its own technology and intellectual property, SQC will continue to work with CQC2T and other participants in Australian and international quantum computing ecosystems to create and develop a silicon quantum computing industry in Australia. and, ultimately, to offer its products. and services to global markets.

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