UNSW Canberra researchers, Dr Hidehiro Yonezawa and Dr Shota Yokoyama, are part of an international team opening up new possibilities for quantum computing.

The team has produced a prototype of a large-scale quantum computer made of laser light.

Quantum computers are expected to transform most industries, including medicine, finance and communication, however there are a number of obstacles that must be overcome before this technology can be used to solve real-world problems.

The new research, published by Science, addresses one of these key hurdles – scalability.


Following on from their recent publication in @sciencemagazine, #UNSWCBR and @QuantumC2T researchers explain the "next generation" in #QuantumComputing https://t.co/5OacCNBonG pic.twitter.com/n8Eiqyshxw

— UNSW Canberra (@UNSWCanberra) November 8, 2019

“We know that once we have large-scale quantum computers, we can do factorisation very quickly, so it will have a huge impact on cyber security,” Dr Hidehiro Yonezawa said.

“We believe our experiment actually creates a platform for hardware for quantum computation, which will lead to some real practical quantum computation in the future.”

Conventional computers solve problems using binary code, and they perform calculations one after another. A quantum computer could solve a number of calculations simultaneously and provide all the possible outcomes at the same time.

Since the 1980s, when quantum computing was first explored, a number of designs for quantum processors have been proposed. The challenge lies in building these designs on a larger scale. 

The research team proposes an entirely new design that is both feasible and scalable.

“The structure and the scale are very important for universal and scalable quantum computation,” Dr Yonezawa explained. 

“This time we succeeded at both for the first time. In our approach we used a quantum state of light called a squeezed state.

The squeezed state is created with a laser light and then weaved into a cluster with a network of mirrors, beam splitters and optical fibres.

“Although the theoretical idea for scaling up quantum computers using light was already proposed in 2011, there were difficulties with the experiment that had to be solved to achieve it,” Dr Yokoyama said.

“Based on the discussion with international researchers, we came up with a new experimental setup.”

Dr Yonezawa and Dr Yokoyama are experimentalists with a theoretical background, so they played a role in bridging the theory and experiment.

The research team included RMIT University’s Dr Menicucci and Dr Rafael Alexander from the University of New Mexico. A team of experimentalists at the University of Tokyo, led by Professor Akira Furusawa, performed the ground-breaking experiment.

“I think our new scheme will be the next generation of quantum computers,” Dr Yokoyama said.

“This is the first time that’s shown a large-scale computer is possible using optics.”

Generation of time-domain-multiplexed two-dimensional cluster state was published in Science (DOI: 10.1126/science.aay2645)