Australian experiment shines light on a new pathway for quantum technology

AN EXPERIMENTAL breakthrough by Australian researchers could prove highly valuable in building the supercomputers of the future. 2, 20183:56pm

Blueprints released for revolutionary quantum computer0:59

Researchers have unveiled a set of blueprints for a quantum computer set to raise the potential limits of computing.

IBM quantum computing lab.Source:Supplied

SCIENTISTS in Australia have for the first time demonstrated the protection of correlated states between paired photons — packets of light energy — that could one day prove valuable in building the supercomputers of the future.

The experimental breakthrough showed a way to protect correlated photons from losing information encoded in them and researchers believe it could open the door to building a new type of quantum bit, known as qubits, which are the building blocks of quantum computers.

“We’ve developed a chip that can guide pairs of correlated photons with immunity to some imperfections and defects,” lead researcher and nanophysicist Dr Andrea Blanco-Redondo from the University of Sydney’s Nano Institute told

The chip is like the chips you have in your phone that guide and use electrons to process information, but instead it processes photons. Unlike electrons, photons are not perturbed by the thermal or electromagnetic environment and hold the promise of faster and more energy-efficient machines. However scaling quantum devices based on photonic qubits has been limited due to scattering loss and other errors — until now.

The scientists played with light symmetries “to create very robust highways for photons at the edge of the chip” which can be used to transfer information to logic gates which are the switches needed to operate algorithms written for quantum computers.

“We can now propose a pathway to build robust entangled states for logic gates using protected pairs of photons,” Dr Blanco-Redondo said.

An artist’s impression of the entangled photons at the edge of the chip.

An artist’s impression of the entangled photons at the edge of the chip.Source:Supplied

Classical computational switches are in simple binary forms of zero or one. Quantum switches exist in a state of “superposition” that combine zero and one.

Protecting quantum information long enough so that quantum machines can perform useful calculations is one of the biggest challenges in modern physics. Useful quantum computers will require millions or billions of qubits to process information but so far the best experimental devices have about 20 qubits.

While Dr Blanco-Redondo says when talking about quantum computing, this research is working on issues at a very “fundamental” and “basic” level of quantum science, the breakthrough holds potential to prove very useful in the future of quantum computing by demonstrating a way to protect and deliver information encoded in paired photons.

The research, which also involved Dr Bryn Bell of Oxford University and researchers in Israel, was published today in the journal Nature.

Professor Stephen Bartlett, a theoretical quantum physicist at Sydney University, who was not involved in the study, said: “Dr Blanco-Redondo’s result is exciting at a fundamental level.

“What it means for quantum computing is unclear as it is still early days. But the hope is that the protection offered by these edge modes could be used to protect photons from the types of noise that are problematic for quantum applications.”

Dr Blanco-Redondo designed and performed the experiment in the Sydney Nanoscience Hub with Dr Bryn Bell, previously at the University of Sydney and now at the University of Oxford.



Quantum computers — which process information at the scale of elementary particles — could operate millions of times faster than today’s most advanced supercomputers. They offer the extraordinary potential to analyse in minutes problems a conventional computer could take thousands of years to solve.

The technology is still in its infancy but it’s predicted that it could have a major impact on healthcare, communications, financial services, transportation, artificial intelligence, weather forecasting and many other areas.

Some even say it could lead to a “cryptocalypse” in national security where state secrets, your emails, bank accounts and credit cards are no longer safe because quantum computers could break traditional internet security programs. It’s this sort of speculation that has seen the race for quantum computing likened to the Manhattan Project, the team of US scientists who won the race to build the first atomic bomb.

But it’s very early days and the science used to build qubits — whether that involves, electrons, atoms or photons — remains largely experimental.

“All these technologies at the moment hold some promise to provide a route to quantum computers that can surpass the processing power of classical computers and nobody know which technology will be the winner.

“That is why there are very important efforts in all of them.”

That message is mirrored by Australian of the year, Professor Michelle Simmons from the University of New South Wales, who is widely regarded as a world-leading researcher in quantum physics.

Speaking to in September following a White House summit on quantum science, she said there is plenty of work to be done by researchers around the world.

“There is still a lot of the fundamental and applied research that needs to happen before it becomes completely commercial. There’s lots of different areas in the quantum space — there’s quantum sensing, quantum communications, quantum computing and fundamental quantum technology,” she said.

“A lot of things are still unknown towards applications for the future.”



Add your comment to this story


Join the conversation, you are commenting as Logout

MORE IN science