Weak measurements measure probability amplitudes (and very little else)

TL;DR

Weak measurements provide a way to directly access quantum probability amplitudes, clarifying their properties and resolving paradoxes associated with weak values in quantum mechanics.

Contribution

The paper demonstrates that weak measurements measure quantum probability amplitudes rather than probabilities, offering a new perspective on their interpretation.

Findings

Weak values correspond to quantum probability amplitudes.

Weak measurements clarify the nature of quantum paths.

The approach resolves common paradoxes in weak measurement theory.

Abstract

Conventional quantum mechanics describes a pre- and post-selected system in terms of virtual (Feynman) paths via which the final state can be reached. In the absence of probabilities, a weak measurement (WM) determines the probability amplitudes for the paths involved. The weak values (VW) can be identified with these amplitudes, or their linear combinations. This allows us to explain the "unusual" properties of the VW, and avoid the "paradoxes" often associated with the WM.