​Stopping light a quantum leap for ANU

The Australian National University has successfully manipulated the interaction of light and atoms in an experiment which has brought the research team one step closer to quantum computing.

Physicists at the Australian National University (ANU) have successfully completed an experiment to stop light, similar to the way Kylo Ren used the force to stop a laser blast.

Jesse Everett from the Research School of Physics and Engineering (RSPE) and Australian Research Council (ARC) Centre of Excellence for Quantum Computation and Communication Technology at ANU, said controlling the movement of light was a critical step in developing future quantum computers.

"Optical quantum computing is still a long way off, but our successful experiment to stop light gets us further along the road," Everett said. "It's pretty amazing to look at a sci-fi movie and say we actually did something that's a bit like that."

Everett said quantum computers based on light could connect easily with communication technology such as optic fibres and had potential applications in fields such as medicine, defence, telecommunications, and financial services.

The research team's experiment to created a light trap by shining infrared lasers into ultra-cold atomic vapour.

"It's clear that the light is trapped, there are photons circulating around the atoms," he said. "The atoms absorbed some of the trapped light, but a substantial proportion of the photons were frozen inside the atomic cloud."

According to the university, the light-trap experiment demonstrated incredible control of a very complex system, allowing the research team to manipulate the interaction of light and atoms with great precision.

Co-researcher Dr Geoff Campbell from ANU said photons mostly passed by each other at the speed of light without any interactions, while atoms interacted with each other readily.

"Corralling a crowd of photons in a cloud of ultra-cold atoms creates more opportunities for them to interact," Campbell said. "We're working towards a single photon changing the phase of a second photon. We could use that process to make a quantum logic gate, the building block of a quantum computer."

The research was supported by funding from the ARC Centre of Excellence for Quantum Computation and Communication Technology, which involves ANU, University of New South Wales (UNSW), University of Melbourne, University of Queensland, Griffith University, University of Sydney, Australian Defence Force Academy, along with 12 international university and industry partners.

UNSW officially opened its new Centre for Quantum Computation and Communications Technology in April, where a team of researchers are racing to build the world's first quantum computer in silicon.

Well on their way to achieving their goal, engineers from the university already unlocked the key to enabling quantum computer coding in silicon, announcing in November that the team had the capability to write and manipulate a quantum version of computer code using two quantum bits (qubits) in a silicon microchip.

According to UNSW, in achieving this breakthrough the team has removed lingering doubts that such operations can be made reliably enough to allow powerful quantum computers to become a reality.

The breakthrough followed on from an announcement made in October when another team of engineers from the university built a quantum logic gate in silicon, which made calculations between two qubits of information possible.

To advance its own research in quantum computing, The University of Sydney was awarded part of a multimillion dollar research grant in May from the United States Office of the Director of National Intelligence.

Later that month, researchers from the University of Western Australia (UWA) and the University of Bristol in the United Kingdom got together to test an early prototype of a quantum computer.

The Australian government announced the launch of nine new ARC Centres of Excellence earlier this month, handing out AU$283.5 million to fund specialised research. As part of the funding, ANU scored a new centre, the ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions, that will aim to answer fundamental questions in astrophysics.


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