The race is on to build a quantum computer capable of solving real-world problems, and researchers are taking more than one approach to get there.
Thursday 9 February 2023
For more than two decades, Professor Andrew Dzurak and his colleagues at UNSW Sydney have been trying to fulfil a dream that was once considered impossible during our lifetime: to build a quantum computer that can reliably solve any problem thrown at it.
“We are very much focused on building a universal quantum computer that is error-corrected and that will solve a much broader class of problems than is available today,” says Dzurak, who recently founded Sydney-based quantum computing startup, Diraq, in May 2022.
But building a quantum computer with enough horsepower to crunch useful calculations is no easy task. To make a genuine real-world impact, quantum computers will need millions to billions of qubits – the basic units of information in quantum systems – to begin solving problems that are out of reach for classical computers. To put that in perspective, the most powerful quantum computers in the world today only have between 50 and 100 qubits, says Dzurak. “We’re still out by many tens of thousands before we have enough qubits to do these calculations,” he says.
But there are many paths to engineering a quantum computer that trumps them all. At Diraq, the approach is all about mixing the new with the old. Dzurak and his team are harnessing electron spins in silicon quantum dots – nanosized structures with semiconducting properties – with the aim of one day cracking one billion qubits.
Diraq’s quantum system relies on silicon, the chemical element that’s been a trusted ally of electronic devices for more than half a century. That means the company’s quantum chips and their tiny components can be manufactured in the same way and at the same facilities as today’s computers and smartphones. It also means millions of qubits can be crammed onto a single chip instead of a few thousand at most, says Dzurak.
“It’s not just the fact that they’re easier to manufacture,” says Dzurak. “It’s also that you have a much more compact system that consumes less energy and will be cheaper to run.”
The technology is firmly rooted in years of academic research, which has yielded more than 40 patents and several milestone discoveries. In 2015 for instance, Dzurak and his team built the world’s first quantum logic gate in silicon, making it possible for two qubits to communicate with each other – the first step to building a quantum computer that can make useful calculations. Dzurak saw glimmers of commercial potential in the results. “I realised just how promising this technology was,” says Dzurak. “And I could see the potential to manufacture these qubits in very, very large numbers.”
A ‘lighter’ approach
Silicon is also the element of choice for PsiQuantum, a quantum computing startup led by Australian CEO and co-founder Jeremy O’Brien, and headquartered in Palo Alto, California. But instead of using quantum dots as qubits, PsiQuantum relies on photons – particles of light – to represent quantum information.
While some view photonics as the ‘contrarian bet’ in the menagerie of quantum computing approaches, working with light has its advantages.
According to O’Brien, one benefit is that – unlike matter-based quantum computing techniques, such as ion-trapping and superconducting circuits – photonic qubits aren’t impacted by electromagnetic interference. This makes them robust and stable carriers of quantum information.
It’s relatively easy to shuttle photonic qubits between devices due to their compatibility with existing fibre-optic networks. They also operate at less stringent low temperatures than alternatives, which makes cooling power at utility scale more feasible. “We believe that photons are the fastest and most promising route to get to that million-qubit utility scale,” says O’Brien, who co-founded PsiQuantum in 2015.
The team appears to be onto something. Since opening its doors almost a decade ago, PsiQuantum has attracted close to AUD$1 billion across its funding rounds. Three years ago, the startup joined forces with semiconductor manufacturing heavyweight GlobalFoundries to manufacture silicon photonic and electronic chips – the building blocks of the company’s quantum computing system.
The PsiQuantum team has also incorporated a single photon detector into the system and is now developing a high-performance optical switch. This will control the flow of light without losing precious photons, making the system more reliable. It’s a lot of work, but PsiQuantum’s utility-scale quantum computer is edging closer to reality. “We’re pretty far along,” says O’Brien. “We’ve improved the architecture dramatically and reduced the size of the system.”
A wealth of opportunities
While it’s still some time before quantum computers will be solving massive problems in sectors such as healthcare, finance and security, O’Brien and his team are thinking ahead. Last year, PsiQuantum launched Qlimate, an initiative focused on accelerating the transition to sustainable technologies through quantum computing. Qlimate’s foundational members include Australian renewable energy firm Fortescue Future Industries.
O’Brien says creating a sustainable future with quantum computing is one area where Australia could shine, due to its rich natural resources. “Australia could become one of the global superpowers in sustainability,” he says. “Quantum computing could be a very powerful tool for doing that.”
Australia’s long legacy in the field has also made it fertile ground for quantum opportunities, with universities forming the backbone of discovery and innovation. At the centre of this vast quantum landscape is the Sydney Quantum Academy, a partnership of four leading universities – Macquarie University, UNSW Sydney, the University of Sydney and the University of Technology Sydney, supported by the NSW Government. It’s focused on building the country’s burgeoning quantum economy by collaborating with academia, industry and government. SQA also powers the Quantum Australia 2023 Conference and Careers Fair which this year will be held on February 21-23. Quantum Australia is designed to showcase Australian ingenuity in the quantum field and the awesome potential of emerging quantum technologies.
For O’Brien, Australia’s quantum prowess is clear. “Australia has had half a dozen to a dozen institutions researching quantum computing for the last few decades,” he says. “Not many countries can claim that. You can see the benefits in the richness and depth of the Australian ecosystem today.”
Want to learn more about the Australian quantum ecosystem?
If you missed Quantum Australia 2023 you can still access all 21 recorded panels and presentations on-demand on the Quantum Australia 2023 virtual platform, after securing a virtual ticket. Recordings will be available until 27 April 2023. Or sign up to Sydney Quantum Academy’s mailing list to be notified of Quantum Australia 2024, other events and quantum news and opportunities.