Quantum world-first: Researchers reveal accuracy of two-qubit calculations in silicon

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Huge leap forward in quantum computing, two qubits operations are essential for quantum processing.

For the first time ever, researchers have measured the fidelity—that is, the accuracy—of two-qubit logic operations in silicon, with highly promising results that will enable scaling up to a full-scale quantum processor.

The research, carried out by Professor Andrew Dzurak's team in UNSW Engineering, was published today in the world-renowned journal Nature.

The experiments were performed by Wister Huang, a final-year Ph.D. student in Electrical Engineering, and Dr. Henry Yang, a senior research fellow at UNSW.

"All quantum computations can be made up of one-qubit operations and two-qubit operations—they're the central building blocks of quantum computing," says Professor Dzurak.

"Once you've got those, you can perform any computation you want—but the accuracy of both operations needs to be very high."

In 2015 Dzurak's team was the first to build a quantum logic gate in silicon, making calculations between two qubits of information possible—and thereby clearing a crucial hurdle to making silicon quantum computers a reality.

A number of groups around the world have since demonstrated two-qubit gates in silicon—but until this landmark paper today, the true accuracy of such a two-qubit gate was unknown.

Accuracy crucial for quantum success

"Fidelity is a critical parameter which determines how viable a qubit technology is—you can only tap into the tremendous power of quantum computing if the qubit operations are near perfect, with only tiny errors allowed," Dr. Yang says.

In this study, the team implemented and performed Clifford-based fidelity benchmarking—a technique that can assess qubit accuracy across all technology platforms—demonstrating an average two-qubit gate fidelity of 98%.

"We achieved such a high fidelity by characterising and mitigating primary error sources, thus improving gate fidelities to the point where randomised benchmarking sequences of significant length—more than 50 gate operations—could be performed on our two-qubit device," says Mr Huang, the lead author on the paper.

Quantum computers will have a wide range of important applications in the future thanks to their ability to perform far more complex calculations at much greater speeds, including solving problems that are simply beyond the ability of today's computers.

https://phys.org/news/2019-05-quantu...two-qubit.html

[Grokmaster]

Is it all the sending and receiving of varying millivolt impulses from the source, via the inherent circuitry of the silicon ?

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Is it all the sending and receiving of varying millivolt impulses from the source, via the inherent circuitry of the silicon ?