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Quantum Computing Closer to Reality

Physicists have brought quantum computing a step closer to reality by stopping light in a new experiment.

Lead researcher Mr Jesse Everett of the Australian National University said that controlling the movement of light was critical to developing future quantum computers, which could solve problems that are too complex for today’s most advanced 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.

He said quantum computers based on photons of light could connect easily with optical fibres used in communications technologies, and had potential applications in fields such as medicine, defence, telecommunications and financial services.

The research team’s experiment, published in Nature Physics (, 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,” Everett said. “The atoms absorbed some of the trapped light, but a substantial proportion of the photons were frozen inside the atomic cloud.”

Everett likened the phenomenon to a scene from Star Wars: The Force Awakens when Kylo Ren used the Force to stop a laser blast mid-air.

A/Prof Ben Buchler, who leads the research team, said that the light-trap experiment demonstrated incredible control of a very complex system. “Our method allows us to manipulate the interaction of light and atoms with great precision,” he said.

Co-researcher Dr Geoff Campbell explained that 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,” he 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,” Campbell said.