Researchers at the Universities of Melbourne and Manchester have invented a breakthrough technique for manufacturing highly purified silicon that brings powerful quantum computers a big step closer.
The new technique to engineer ultra-pure silicon makes it the perfect material to make quantum computers at scale and with high
A qubit – such as an atomic nucleus, electron, or
Silicon’s Role in Quantum Technology
Lead author Ravi Acharya, a joint University of Manchester/University of Melbourne Cookson Scholar, said the great advantage of silicon chip quantum computing was it used the same essential techniques that make the chips used in today’s computers.
“Electronic chips currently within an everyday computer consist of billions of transistors — these can also be used to create qubits for silicon-based quantum devices. The ability to create high quality silicon qubits has in part been limited to date by the purity of the silicon starting material used. The breakthrough purity we show here solves this problem.”
Professor Jamieson said the new highly purified silicon computer chips house and protect the qubits so they can sustain quantum coherence much longer, enabling complex calculations with greatly reduced need for error correction.
“Our technique opens the path to reliable quantum computers that promise step changes across society, including in artificial intelligence, secure data and communications, vaccine and drug design, and energy use, logistics, and manufacturing,” he said.
Silicon – made from beach sand – is the key material for today’s information technology industry because it is an abundant and versatile semiconductor: it can act as a conductor or an insulator of electrical current, depending on which other chemical elements are added to it.
“Others are experimenting with alternatives, but we believe silicon is the leading candidate for quantum computer chips that will enable the enduring coherence required for reliable quantum calculations,” Professor Jamieson said.
Purifying Silicon for Quantum Computing
“The problem is that while naturally occurring silicon is mostly the desirable isotope silicon-28, there’s also about 4.5 percent silicon-29. Silicon-29 has an extra neutron in each previously published research with the ARC Centre of Excellence for Quantum Computation and Communication Technology, the University of Melbourne set – and still holds – the world record for single-qubit coherence of 30 seconds using silicon that was less purified. 30 seconds is plenty of time to complete error-free, complex quantum calculations.
Professor Jamieson said the largest existing quantum computers had more than 1000 qubits, but errors occurred within milliseconds due to lost coherence.
“Now that we can produce extremely pure silicon-28, our next step will be to demonstrate that we can sustain quantum coherence for many qubits simultaneously. A reliable quantum computer with just 30 qubits would exceed the power of today’s supercomputers for some applications,” he said.
This latest work was supported by research grants from the Australian and UK governments. Professor Jamieson’s collaboration with the University of Manchester is supported by a Royal Society Wolfson Visiting Fellowship.
A 2020 report from Australia’s CSIRO estimated that quantum computing in Australia has potential to create 10,000 jobs and $2.5 billion in annual revenue by 2040.
“Our research takes us significantly closer to realizing this potential,” Professor Jamieson said.
Reference: “Highly 28Si enriched silicon by localised focused ion beam implantation” 7 May 2024, Communications Materials.
DOI: 10.1038/s43246-024-00498-0