title: Observing the average trajectories of single photons in a two-slit interferometer.
abstract: A consequence of the quantum mechanical uncertainty principle is that one may not discuss the path or "trajectory" that a quantum particle takes, because any measurement of position irrevocably disturbs the momentum, and vice versa. Using weak measurements, however, it is possible to operationally define a set of trajectories for an ensemble of quantum particles. We sent single photons emitted by a quantum dot through a double-slit interferometer and reconstructed these trajectories by performing a weak measurement of the photon momentum, postselected according to the result of a strong measurement of photon position in a series of planes. The results provide an observationally grounded description of the propagation of subensembles of quantum particles in a two-slit interferometer.
authors.affiliation: Centre for Quantum Information and Quantum Control and Institute for Optical Sciences, Department of Physics, University of Toronto, 60 St. George Street, ON M5S 1A7, Canada.
authors.forename: Sacha
authors.initials: S
authors.lastname: Kocsis
authors.forename: Boris
authors.initials: B
authors.lastname: Braverman
authors.forename: Sylvain
authors.initials: S
authors.lastname: Ravets
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Stevens
authors.forename: Richard P
authors.initials: RP
authors.lastname: Mirin
authors.forename: L Krister
authors.initials: LK
authors.lastname: Shalm
authors.forename: Aephraim M
authors.initials: AM
authors.lastname: Steinberg