Weaving quantum processors out of laser light

Weaving quantum processors out of laser light

Researchers open a new avenue to quantum computing with a breakthrough prototype: a large-scale quantum processor made entirely of light.

An international team of scientists from Australia, Japan and the United States has produced the prototype, based on a design 10 years in the making.

Quantum computers promise fast solutions to hard problems, but they need a large number of quantum components and must be relatively error free.

Current quantum processors are small and prone to errors. The new design provides an alternative solution, using light, to reach the scale needed to eventually outperform classical computers.

The new research, published in Science, produced a quantum processor made of laser light that has built-in scalability, allowing the number of quantum components to scale to extreme numbers.

Graphic of the entanglement structure of a large-scale quantum processor made of light The entanglement structure of a large-scale quantum processor made of light. Credit: Shota Yokoyama 2019

Lead researcher Dr Nicolas Menicucci is a Vice-Chancellor's Senior Research Fellow and Chief Investigator at the RMIT node of the ARC Centre of Excellence for Quantum Computation and Communication Technology (CQC2T).

“While today’s quantum processors are impressive, it isn’t clear if the current designs can be scaled up to extremely large sizes,” Menicucci said.

 “Our approach starts with extreme scalability – built in from the very beginning – because the processor, called a ‘cluster state’, is made out of light.” 

Using light as a quantum processor

A cluster state is a large collection of entangled quantum components that performs quantum computations when measured in a particular way.

 “To be useful for real-world problems, a cluster state must be both large enough and have the right entanglement structure,” Menicucci said.

“In the two decades since they were proposed, all previous demonstrations of cluster states have failed on one or both of these counts. Ours is the first ever to succeed at both.”

18 October 2019

Share

Optical and laser research equipment. A network of optical devices – mirrors, beamsplitters and optical fibres – weave laser light into an optical quantum processor. Photo: CQC2T

To make the cluster state, specially-designed crystals convert ordinary laser light into a type of quantum light called “squeezed light”, which is then weaved into a cluster state by a network of mirrors, beamsplitters and optical fibres.

The design allows for a relatively small experiment to generate an immense two-dimensional cluster state with scalability built in. 

Although the levels of squeezing – a measure of quality – are currently too low for solving practical problems, the design is compatible with approaches to achieve state-of-the-art squeezing levels.

The team says their achievement opens up new possibilities for quantum computing with light.

Dr Hidehiro Yonezawa, Chief Investigator, CQC2T at UNSW Canberra, said the researchers had -  for the first time in any system - made a large-scale cluster state whose structure enables “universal quantum computation”.

“Our experiment demonstrates that this design is feasible - and scalable.”

Dr Nicolas Menicucci, Chief Investigator at CQC2T. Dr Nicolas Menicucci, Chief Investigator at the RMIT node of CQC2T.

The experiment was an international effort, with the design developed through collaboration by Menicucci, Dr Rafael Alexander from the University of New Mexico and UNSW Canberra researchers Yonezawa and Dr Shota Yokoyama. A team of experimentalists at the University of Tokyo, led by Professor Akira Furusawa, performed the groundbreaking experiment.

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

 

Story: Gosia Kaszubska

18 October 2019

Share

  • Research
  • Science and technology
Engage

Related News

Dr. Darcy Allen on stage in front of PowerPointPowerPoint slide reading 'The Supertransition'

“We are on the cusp of a technology-driven ‘supertransition’” - RMIT expert says deep economic change is occurring with profound consequences for business

RMIT economist Dr. Darcy Allen says the world is in an economic ‘supertransition’: profound economic change driven by the simultaneous combination of technologies.

health-transformation-lab-1220x732.jpg

Top five health tech trends give a glimpse of the future of healthcare

A new report reveals the five most significant tech transformations for health – and how to advance adoption over the next 12 months.

news-quantum-team-1220px.jpg

A promising leap towards computers with light-speed capabilities

Scientists have created a reprogrammable light-based processor, a world-first, that they say could usher in a new era of quantum computing and communication.

Geometric building texture.

New hub to make diamond-based quantum computers

A joint research and development hub will harness the strength of synthetic diamonds to build a new generation of quantum computers.

Show more
aboriginal flag
torres strait flag

Acknowledgement of Country

RMIT University acknowledges the people of the Woi wurrung and Boon wurrung language groups of the eastern Kulin Nation on whose unceded lands we conduct the business of the University. RMIT University respectfully acknowledges their Ancestors and Elders, past and present. RMIT also acknowledges the Traditional Custodians and their Ancestors of the lands and waters across Australia where we conduct our business - Artwork 'Sentient' by Hollie Johnson, Gunaikurnai and Monero Ngarigo.

More information