Quantum computers a step closer to reality

melbourne: physicists have brought quantum computers - which could solve problems too complex for today's most advanced machines - a step closer to reality by successfully stopping light in a new experiment. lead researcher jesse everett from australian national university (anu) said controlling the movement of light was critical to 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," said everett. he said quantum computers based on particles of light - photons - could connect easily with communication technology such as optic fibres and have potential applications in fields such as medicine, defence, telecommunications and financial services. the research team's experiment - which created a light trap by shining infrared lasers into ultra-cold atomic vapour - was inspired by everett's discovery of the potential to stop light in a computer simulation. "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," he said. everett likened the team's experiment to a scene from star wars: the force awakens when the character kylo ren used the force to stop a laser blast mid-air. "it's pretty amazing to look at a sci-fi movie and say we actually did something that's a bit like that," he said.   associate professor ben buchler, who leads the anu research team, said 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," said buchler.   co-researcher 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," said campbell. "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," he said. the research was published in the journal nature physics.