Anomalous weak values emerging from strong interactions between light and matter Academic Article uri icon


  • Some predictions regarding pre- and post-selected particles are far-reaching, thereby requiring validation with standard quantum measurements in addition to the customary weak measurements used so far, as well as other advanced techniques. We go further in this research program with two thought experiments incorporating novel yet feasible validation methods of unconventional light-matter interactions. An excited atom traverses a Mach-Zehnder interferometer (MZI) under a special combination of pre- and post-selection. In the first experiment, photons emitted by the superposed atom, after being hit by two laser beams, are individually counted. Despite the interaction having definitely taken place, as revealed by the atom becoming ground, the numbers of photons emitted from each arm of the MZI are predicted, at the ensemble level, to be different from those expected with standard stimulated emission of a pre-selected-only atom. In the second experiment, the atom spontaneously emits a photon while still in the MZI. This photon later serves as a strong measurement of the atom's energy upon hitting a photographic plate. The experiment is repeated to enable an interference effect of the emitted photons. Surprisingly, the latter gives the appearance that the photons have been emitted by the atom from a position much farther from the two MZI arms L and R, as if in a "phantom arm" R'. Nevertheless, their time of arrival is similar to that of photons coming from L and R. These experiments also emphasize the key role of negative weak values of atoms under pre- and post-selection. The novel verification methods resemble weak measurements in some aspects, yet result from an unambiguous atomic transitions verified by the detected photons.

publication date

  • January 1, 2017