Superposition of wave and particle state

consciousnessRealisation of quantum Wheeler’s delayed-choice experiment

Tang et al, University of Science & Technology of China

Nature Photonics, 6, pp. 602-6, doi: 10.1038/nphoton.2012.179, 19 August 2012

Bohr’s complementarity principle proposed that quanta were either in a wave state or a particle state according to how an experiment was performed. Tang’s study was a refinement of Wheeler’s delayed choice experiment. In this only after a photon has passed through two slits or a beam splitter is a detector put in place. This experiment has been considered to exclude the possibility that hidden variables informed the quanta about the nature of the detecting device, and in this respect confirmed Bohr’s original view that the nature of the experiment determined the state of the quanta.

The refinement in the Tang experiment is that the detection device is itself in a quantum-superposition state of producing and not producing interference fringes. Single photons are sent into an experimental device with this quantum-state detector, and are shown to produce very different interference fringes from the same experiment performed with a classical-state detector. More significantly photons are observed not to just be in a wave or a particle state, but to be in a superposition of the wave and particle state of the photon. This does not happen when a classical detector is used, and the quantum detector is responsible for the different outcome. It is stated that this has not been observed before, and thus reveals a new aspect of the wave-particle duality. Previously, it was understood that quanta could change from the wave to the particle state, but this experiment shows that they can exist as a superposition of the wave state and the particle state.

It seems possible to speculate that this finding may have some bearing on research into photosynthetic organisms where recoherence or flipping back from particle to wave states plays a role in the efficient transport of energy.

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