We report an experimental test of complementarity using clock-triggered single-photon pulses emitted by an individual N-V color center in a diamond nanocrystal. The single photons are sent into a Mach-Zehnder interferometer with an output beamsplitter of adjustable reflection coefficient R. In addition, the choice of introducing or removing this beamsplitter is random and relativistically space-like separated from the entering of the photon inside the interferometer, as required for the Wheeler's delayed-choice regime. Each set value of R allows us to observe interference with visibility V and to obtain incomplete which-path information characterized by the distinguishability D. The measured values of V and D are found to obey the complementarity relation V^2 + D^2 =< 1.
Cite
@article{arxiv.0801.0979,
title = {Delayed-choice test of complementarity with single photons},
author = {Vincent Jacques and E. Wu and Frédéric Grosshans and François Treussart and Philippe Grangier and Alain Aspect and Jean-François Roch},
journal= {arXiv preprint arXiv:0801.0979},
year = {2009}
}