Foundations of Physics

, Volume 37, Issue 2, pp 295–305

Paradox in Wave-Particle Duality


    • Department of Physics & AstronomyRowan University
  • Eduardo Flores
    • Department of Physics & AstronomyRowan University
  • Keith F. McDonald
    • Department of Physics & AstronomyRowan University
  • Ernst Knoesel
    • Department of Physics & AstronomyRowan University

DOI: 10.1007/s10701-006-9102-8

Cite this article as:
Afshar, S.S., Flores, E., McDonald, K.F. et al. Found Phys (2007) 37: 295. doi:10.1007/s10701-006-9102-8

We report on the simultaneous determination of complementary wave and particle aspects of light in a double-slit type “welcher-weg” experiment beyond the limitations set by Bohr’s Principle of Complementarity. Applying classical logic, we verify the presence of sharp interference in the single photon regime, while reliably maintaining the information about the particular pinhole through which each individual photon had passed. This experiment poses interesting questions on the validity of Complementarity in cases where measurements techniques that avoid Heisenberg’s uncertainty principle and quantum entanglement are employed. We further argue that the application of classical concepts of waves and particles as embodied in Complementarity leads to a logical inconsistency in the interpretation of this experiment.


principle of complementaritywave-particle dualitynon- perturbative measurementsdouble-slit experimentAfshar experiment

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© Springer Science+Business Media, LLC 2007