Verifying the future of quantum computing

Press release issued: 30 July 2014 Physicists are one step closer to proving the reliability of a quantum computer - a machine which promises to revolutionise the way we trade over the internet and provide new tools to perform powerful simulations. By harnessing the strange laws of quantum mechanics, future quantum computers offer the hope of quickly solving problems that would take even the best supercomputers the lifetime of the universe to solve. Although a fully-fledged commercial quantum computer is a long-term endeavour, researchers have been testing a more basic quantum device - called a 'Boson Sampler' - which focuses on carrying out one fixed task using the behavior of particles of light, called photons. An important question that researchers and engineers are trying to answer is whether large systems of quantum particles behave as predicted by quantum mechanics. Because conventional - or classical - computers cannot simulate large versions of these quantum devices, it is not clear how to verify that they are truly performing complex tasks, or if nature takes a shortcut and sidesteps quantum mechanics. Researchers at the University of Bristol have devised and demonstrated new techniques to address this problem, which are published today [30 July], alongside similar research from their counterparts at Sapienza University of Rome. They have shown how to measure certain properties of Boson Samplers to provide experimental evidence to support the correct operation.