Weak Measurements of Trajectories

Miguel Orszag

A. Matzkin

Weak values, obtained from weak measurements, attempt to describe the properties of a quantum system as it evolves from an initial to a final state, without practically altering this evolution. Trajectories can be defined from weak measurements of the position, or inferred from weak values of the momentum operator. The former can be connected to the asymptotic form of the Feynman propagator and the latter to Bohmian trajectories. Employing a time-dependent oscillator as a model, this work analyzes to what extent weak measurements can shed light on the underlying dynamics of a quantum system expressed in terms of trajectories, in particular by comparing the two approaches.

Maciej Błaszak, Ziemowit Domański

A. Matzkin

We propose a scheme allowing us to observe the evolution of a quantum system in the semiclassical regime along the paths generated by the propagator. The scheme relies on performing consecutive weak measurements of the position. We show how "weak trajectories" can be extracted from the pointers of a series of devices having weakly interacted with the system. The properties of these weak trajectories are investigated and illustrated in the case of a time-dependent model system.

Miguel Orszag

Lynden K. Shalm, Sacha Kocsis, Sylvain Ravets +4 more

We use weak measurements to carry out the first direct observation of the trajectories followed by single photons in a two-slit interferometer. The measured trajectories correspond to those predicted by Bohmian mechanics.