How the result of a measurement of a component of the spin of a spin-1/2 particle can turn out to be 100 without using weak measurements

TL;DR

The paper explores how measurement results for a spin-1/2 particle can appear unphysical, like a value of 100, without employing weak measurements, and clarifies the proper quantum description of such experiments.

Contribution

It demonstrates that unphysical measurement outcomes can arise without weak measurements and clarifies the quantum interpretation of weak-value-type experiments.

Findings

Unphysical results similar to weak values can occur in simple setups without weak measurements.

Proper quantum description resolves apparent paradoxes in weak-value experiments.

The paper clarifies the physical meaning of measurements in weak-value scenarios.

Abstract

We discuss two questions related to the concept of weak values as seen from the standard quantum-mechanics point of view. In the first part of the paper, we describe a scenario where unphysical results similar to those encountered in the study of weak values are obtained using a simple experimental setup that does not involve weak measurements. In the second part of the paper, we discuss the correct physical description, according to quantum mechanics, of what is being measured in a weak-value-type experiment.