Michelle Simmons and her Australian team make strides in developing a true supercomputer, pursuing the idea that cheap silicon is the key around the world, teams of engineers, physicists, mathematicians and engineers are using all kinds of exotic materials in the race to build the world’s first practical quantum computer, capable of processing amounts of data in a matter of hours that would take today’s computers millions of years.
Caesium, aluminium, niobium titanium nitride and diamond are among the substances being used by researchers trying to determine which will best allow particles to maintain a delicate quantum state of superposition, where particles exist across multiple, seemingly counterintuitive states at the same time.
But the decision by researchers at the University of New South Wales (UNSW) in Australia to use cheap and widely available silicon, the building block of all modern electronic devices, has led to significant advances in their attempts to win the quantum race.
The team’s members believe that because silicon is already widely available and used in devices like laptops and mobile phones it will be easier to manufacture and upscale the world’s first functioning quantum computer. And their faith in it has paid dividends.
So groundbreaking have their discoveries been that in December, Telstra announced an in-principle commitment of $10m over the next five years to the team at the university’s centre of excellence for quantum computation and communication technology, and the Commonwealth Bank of Australia also pledged $10m.
Prof Michelle Simmons is director of the centre and an internationally renowned quantum researcher. In the late 1990s, when she was a research fellow in quantum electronics at the Cavendish Laboratory at the UK’s Cambridge University, Simmons read a theoretical paper by Dr Bruce Kane, who was then a quantum researcher at UNSW.
In the paper, Kane put forward a purely theoretical proposal for a scalable quantum computer based on quantum atoms embedded in silicon.
“It was something at the edge of what was feasible but I knew if you could do it, it would be really worthwhile,” Simmons says.
“The proposal relied on building individual single atom devices, but there was no technology to do that. He put forward in the paper two ideas as to how it could be done, similar to techniques I picked up in Cambridge. And after a while of thinking about it, I was like; ‘Yeah. This can be done’. I could see it.”
In 1999, Simmons applied to be part of the research team UNSW was forming to attempt to build the components outlined in Kane’s paper. She has been working to bring Kane’s vision of a quantum computer to life ever since.
“We have been leading for the past five years in silicon,” Simmons says. “With the results we’ve been publishing from 2010 onwards, we’re showing how we can encode information in single atoms, how we can build systems in silicon, and how we can control these systems in silicon.”
In October, UNSW researchers led by Prof Andrew Dzurak cleared a major hurdle in making silicon-based quantum computers a reality by demonstrating calculations between silicon quantum bits, or “qubits”, for the first time. In other words, researchers made the qubits talk to each other, something no researcher had managed before.
To achieve this, the team constructed a device, known as a “quantum logic gate”, that allowed calculations to be performed between two qubits. Until then, researchers had not been able to make two quantum bits talk to each other to create the logic gate, a fundamental building block required for quantum computing using silicon. This is because a quantum computer uses sub-atomic particles, rather than transistors, as its processing unit, giving it its extraordinary power.
One month later another team of researchers from the centre, this time led by Prof Andrea Morello, demonstrated that a quantum version of computer code could be written on a silicon microchip, and did so with the highest level of accuracy recorded.
By “entangling” the two qubits, an electron and the nucleus of a single phosphorus atom, the researchers showed that the particles remained connected after they had been separated so that actions performed on one still affected the other.
This entanglement meant researchers could access a quantum computing language or code vastly richer than standard digital codes used in normal computers. These special codes are essential to giving quantum computers their power.
“Now, we’re aiming to build the first quantum integrated circuit, which we’re aiming for by 2020,” Simmons says.
“Beyond that, we must do error correction, so that if errors come into the chip, you can run multiple processes in parallel to eliminate those errors – and that error correction will take another five years or so.
“Whether we can control the quantum states and all of that at the fundamental level has now been proven. The big killer is, at what point do we build a processor big enough thats it’s faster than a classical computer?
“That means moving away from small scale models to integrated processing devices and prototypes. That’s the challenge, and that can be done, we anticipate, within the next decade.”
Simmons, who won NSW scientist of the year in 2011 and the Eureka prize for leadership in science earlier this year, has worked hard to make the dizzying world of quantum computing more accessible to people. She believes we need to become comfortable with the technology so that when it does become commercially feasible, users are not overwhelmed by it.
She has appeared before thousands to give a TEDx talk explaining her work, while she and her team have created explanatory videos in which they try their best to create analogies to explain the super power quantum computers possess.
She is driven not only by a love of her work and mentoring up-and-coming researchers, she says, but by an urge to prove other people wrong.
“I think it goes back to when I was very young, when my dad played chess with my brother,” she says. “I used to watch and take the moves in, and one day I asked my dad to play with me,” she says.
“He wasn’t expecting that, and he was dismissive of me but eventually said yes. I beat him on the first game. When people don’t expect things of you, that makes you want to prove them wrong.”
Simmons was inspired to pursue science thanks to a “fantastic physics teacher” in high school who used to ask her to explain some of the tougher concepts to the rest of the class. Back then, Simmons wanted to be an astronaut.
“One day my teacher took me to the headmaster’s office, and when we got in there he picked up the phone, rang a number, and passed the phone to me. He had managed to track down a US astronaut and convince him to talk to me about what I needed to do to become one.
“My teacher believed I could do whatever I wanted, and it made a phenomenal difference. I have tried to track him down to let him know how things are going for me, but have never been able to.”
Her work these days is relentless. Her own research, combined with reading research papers to keep abreast of quantum research happening throughout the world, has her working six days a week.
If quantum computers become a reality, they have the potential to rapidly find information in a massive dataset, and be game-changing for fields like medicine, national security, and aeronautics.
“This work is all-consuming,” Simmons says. “At the moment I work every Sunday, and I have three young children, so it’s tough on them.
“But if you’re internationally leading, then you have to keep up with everything, and a huge amount of time goes into that. But I think it’s true of anything in life; if you love it, you’ll want to do it.”