AsianScientist (May 7, 2015) – Researchers at the University of Tokyo have successfully verified Einstein’s proposal of the nonlocality of a single quantum (photon)—the idea that a single photon diffracted by a slit can spread out infinitely, but is never detected in two or more places simultaneously. Their results have been published in the journal Nature Communications.
This elusive phenomenon of nonlocality in quantum mechanics, which has been termed “spooky action at a distance,” spurred a hundred years’ debate among physicists with Einstein’s proposal in 1909. Ever since, physicists have been making zealous efforts towards rigorous confirmation by highly efficient measurement devices. However, detection methods used so far have been for detecting photons as particles. In addition to low detection efficiency, it was theoretically impossible to rigorously verify Einstein’s proposal, since these methods can only detect the presence or absence of photons.
Graduate School of Engineering professor Akira Furusawa, doctoral student Maria Fuwa and their collaborators utilized the wave-like degree of a photon as an electromagnetic wave and used a homodyne measurement technique to measure the photon amplitude and phase with high efficiency. This enabled the group to successfully verify the nonlocality of a single photon with high precision and rigor.
This is not only a significant achievement in the field of fundamental physics, but also opens way to a novel scheme to realize quantum cryptography and quantum computers using both the particle and wave nature of photons.
The article can be found at: Fuwa et al. (2015) Experimental Proof Of Nonlocal Wavefunction Collapse For A Single Particle Using Homodyne Measurements.
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Source: The University of Tokyo.
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