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Observing the average trajectories of single photons in a two-slit interferometer



Sacha Kocsis, Boris Braverman, Sylvain Ravets, Martin Stevens, Richard Mirin, L. Krister Shalm, Aephraim M. Steinberg


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.
Science Magazine


Quantum Optics, Single-Photon Sources, Weak Measurements


Kocsis, S. , Braverman, B. , Ravets, S. , Stevens, M. , Mirin, R. , Shalm, L. and Steinberg, A. (2011), Observing the average trajectories of single photons in a two-slit interferometer, Science Magazine, [online],, (Accessed April 19, 2024)
Created June 2, 2011, Updated October 12, 2021