Or so they say. At CBC News (June 2, 2011), Emily Chung reports, “‘Impossible’ physics feat traces path of light”:
Canadian researchers have traced the average path of single light particles through two slits, probing the limits of a famous physics principle that seemed to suggest doing so wasn’t possible.“We are all just thrilled to be able to see, in some sense, what a photon does as it goes through an interferometer, something all of our textbooks and professors had always told us was impossible,” Aephraim Steinberg, a physicist at the University of Toronto’s Centre for Quantum Information and Quantum Control, said in a statement.
Results were published in Science. It doesn’t exactly break the rule enunciated by Heisenberg’s uncertainty principle of quantum mechanics but
The technique relies on multiple “weak measurements” rather than precise ones that significantly change the particles’ position and trajectory.