Both At A Time
Wave-particle duality tested
Photons, particles of light, are both particles and waves simultaneously. Physicists now give a new demonstration of this wave-particle duality of photons.
Surprisingly, when a photon is observed, it behaves either as a particle or as a wave. But both aspects are never observed simultaneously. In fact, which behaviour it exhibits depends on the type of measurement it is presented with. These astonishing phenomena have been experimentally investigated in the last few years, using measurement devices that can be switched between wave-like and particle-like measurements. In a paper published Nov. 1 in Science, physicists from the University of Bristol give a new twist on these ideas. Dr Alberto Peruzzo, Peter Shadbolt and Professor Jeremy O'Brien from the Centre for Quantum Photonics teamed up with quantum theorists Dr Nicolas Brunner and Professor Sandu Popescu to devise a novel type of measurement apparatus that can measure both particle and wave-like behaviour simultaneously. This new device is powered by quantum nonlocality, another strikingly counter-intuitive quantum effect. Dr Peruzzo, Research Fellow at the Centre for Quantum Photonics, said: "The measurement apparatus detected strong nonlocality, which certified that the photon behaved simultaneously as a wave and a particle in our experiment. This represents a strong refutation of models in which the photon is either a wave or a particle." Professor O'Brien, Director of the Centre for Quantum Photonics, said: "To conduct this research, we used a quantum photonic chip, a novel technology pioneered in Bristol. The chip is reconfigurable so it can be programmed and controlled to implement different circuits. Today this technology is a leading approach in the quest to build a quantum computer and in the future will allow for new and more sophisticated studies of fundamental aspects of quantum phenomena."
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