Dr. Andrew Dzurak, Wister Huang and Dr. Henry Yang.
Researchers at UNSW have measured the accuracy of two-cubit calculations in silicon for the first time, with their results suggesting a strong future for the element in the development of quantum computation.
Publishing their results today in Nature, the team said that their measurement of two-cubit logic operations in silicon will enable scaling up to a full-scale quantum processor.
“All quantum computations can be made up of one-qubit operations and two-qubit operations – they’re the central building blocks of quantum computing,” said Professor Andrew Dzurak, who led the team of engineers.
“Once you’ve got those, you can perform any computation you want – but the accuracy of both operations needs to be very high.”
Dr. Dzurak said that for the scale and complexity of the tasks quantum computers will be assigned to, millions of cubits will be needed, and errors will need to be corrected.
“For error correction to be possible, the qubits themselves have to be very accurate in the first place – so it’s crucial to assess their fidelity,” he said.
“The more accurate your qubits, the fewer you need – and therefore, the sooner we can ramp up the engineering and manufacturing to realise a full-scale quantum computer.”
In this research, the team demonstrated an average two-gate cubit fidelity of 98 percent, using Clifford-based fidelity benchmarking.
Dr. Huang, lead author on the paper said: “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.”
Silicon is a core component of conventional computer processors, with well-understood properties and scope for adaptation of existing production facilities. The research team said that their results demonstrate silicon’s potential for scaling up to the large number of cubits required for universal quantum computing.
“If our fidelity value had been too low, it would have meant serious problems for the future of silicon quantum computing. The fact that it is near 99% puts it in the ballpark we need, and there are excellent prospects for further improvement. Our results immediately show, as we predicted, that silicon is a viable platform for full-scale quantum computing,” Professor Dzurak says.
A UNSW research team led by Professor Dzurak developed the first ever logic gate in silicon in 2015.
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