Inside Australia’s future qubit foundry

In the middle of the University of Sydney’s Darlington campus stands a large building with a glass, silver-lined skin, inside of which scientists are unlocking the secrets of the quantum realm.

It’s getting an upgrade.

The building, opened in 2016 as a state-of-the-art $150 million Nanoscience Hub, is one of the most stable and tightly controlled environments in the world, with research laboratories that are isolated from all external vibration and electromagnetic radiation thanks to the Faraday shields surrounding them.  

In fact, says Professor Stephen Bartlett, Associate Dean in the Faculty of Science at the University of Sydney (USyd), the building is “like a science experiment in itself.”

Bartlett, who is also the lead of the USyd Quantum Theory Group, says the “centrepiece of the whole building” is the nanofabrication cleanroom.

The western half of the building where there are no elevators – which emit electromagnetic radiation – is bathed in amber light to protect the very delicate quantum devices that are being built inside from damaging ultraviolet light.

All of the scientists working at the shiny metal bays and microscopes inside the cleanroom are dressed in full “bunny suits” – to borrow Bartlett’s words – to protect it from the dust, dead skin and other particulate matter our bodies exude.

This cleanroom is where the recently launched $7.4 million Future Qubit Foundry will be housed – a new national facility that will expand and strengthen the work to develop the technology of tomorrow’s quantum computers.

This new breed of computers, in harnessing the mysterious power of the quantum realm, will make even the most powerful supercomputers of today appear sluggish – as early models have already demonstrated.

In 2019, for example, Google claimed its Sycamore quantum computer had achieved “quantum supremacy” by completing a mathematical calculation that is beyond the reach of even the most powerful classical supercomputer. 

“The Future Qubit Foundry will leverage the University of Sydney’s research leadership in advanced quantum technologies and put us at the forefront of next-generation design of qubits,” USyd Deputy Vice-Chancellor (Research), Professor Emma Johnston, said.

Qubits – short for quantum bits – are the building blocks of quantum computers. They are similar to bits in classical computers, but being subatomic particles like photons of light or electrons, they operate according to strange subatomic logic in the way they store and process information.

For example, unlike bits in classical computers, which are always in one of two physical states – usually represented as a numerical binary like 0 or 1 – qubits can exist in a mixed state, due to a phenomenon known in quantum-speak as ‘superposition’.

What’s more, the qubits in a quantum computer can be made to operate interdependently in a state of entanglement rather than independently like bits in a classical computer: one tweak to one qubit will predictably influence all the others, even if they aren’t in contact with one another.

In this ‘inseparable state’, as physicists poetically refer to it, the qubits aren’t multiple distinct objects simply interacting with each other. As far as the maths is concerned, they literally become one thing which can be manipulated and exploited.

Bartlett says these two quantum properties are primarily what give quantum computers their superior computing power: they essentially enable quantum computers to perform many computations in parallel rather than one at a time, like classical computers do.

But Bartlett admits that exactly how the superposition and entanglement of qubits enables a quantum computer to perform simultaneous calculations remains a mystery.

“I don’t think saying [a qubit] can be in multiple at the same time is a satisfactory answer,” he says. “It could be one, it could be zero, but it can also be something else. What is that something else? That gets into the full heart of quantum mechanics and what it is telling us about the world. And we don’t have good answers.”

One thing that quantum physicists like Bartlett do know, however, is that – in true quantum style – qubits, as well as being the major strength of quantum computers, are also their weakness.

This is because qubits are notoriously unstable and fragile: the smallest amount of external noise – for example, electromagnetic radiation or changes in temperature – can cause their fragile state to break in a process known as decoherence, whereby their powerful quantum properties of superposition and entanglement disappear, and they behave more or less like bits in a classical computer.

Therefore, in order to function properly, quantum computers require complete protection from the external environment: they need to be kept in powerful refrigerators at a temperature just above absolute zero – minus 273.15 degrees – which is orders of magnitude colder than interstellar space.

In order to function properly, quantum computers require complete protection from the external environment: they need to be kept in powerful refrigerators at a temperature just above absolute zero.

To reach such extreme temperature, the refrigerators use approximately 10kW continuously – more than about three average houses – and require helium-3, an exceedingly rare and expensive isotope.

The fragility of qubits is one of the major challenges of quantum computing that the Future Qubit Foundry hopes to overcome by fabricating next generation qubits which, according to Bartlett, “are more robust – and perhaps inherently robust – to noise and decoherence, and therefore better able to keep their quantum nature”.

Roughly half of the new funding for the Future Qubit Foundry will be directed towards researching and developing new and improved qubits. The other half will be directed towards buying equipment like electronics infrastructure and refrigerators that are needed to control and operate quantum computers.

“That will allow us to put these new quantum devices to the test,” Bartlett says.

Bartlett sees this investment as an opportunity to get scientific breakthroughs in quantum computing out of university labs and into the world – and also as an invitation to governments and private companies in Australia that “we’re open for business and for collaboration, let’s work together and see if we can build something”.

He hopes this invitation is accepted – and that Australia seizes this unique chance to “lead the world” in quantum computing.

In Bartlett’s expert opinion, it will not be long before quantum computing technology is being widely used for real-world purposes, like developing better batteries, better drugs and solving optimisation problems much more efficiently.

“In 10 years from now, I’d be very surprised if that hasn’t happened,” he says, adding that Transport NSW is already investing in quantum computing technology to try and help solve intractable problems relating to the movement of people.

USyd says the facility will also help ensure Australia can train the quantum workforce needed to operate tomorrow’s quantum tech.

“We have to really think about what’s going to be the impact on our environment of new technologies, and we better start doing that before we roll them out in a big way,” he says. 

This point is particularly relevant to quantum computers, given how “power hungry” the refrigerators are.

“We have to really think about what’s going to be the impact on our environment of new technologies, and we better start doing that before we roll them out in a big way.” 

Professor Stephen Bartlett

But while Bartlett is excited about the Future Qubit Foundry, and quantum computers more generally, he also offers a few words of warning.

Bartlett is also worried about the issue of access and whether only wealthy countries will be the ones to benefit from the quantum computing revolution – especially given that there may never be a room temperature (and therefore low-cost) quantum hardware.

“Is this going to be a technology in 10 or 20 years that only a few nations have access to? I think we need to think long and hard about how to make this technology widely accessible, at least when it’s safe to do so.”

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