A comment on the paper "How can a Result of a Single Coin Toss Turn Out to be 100 Heads" by C. Ferrie and J. Combes

TL;DR

This paper critiques a recent claim that weak values are purely statistical and not inherently quantum, emphasizing that their averaging process involves sign-changing distributions unique to quantum mechanics.

Contribution

The authors refute the claim that weak values are purely classical, clarifying that their averaging involves quantum-specific distributions that can change sign.

Findings

Weak values require sign-changing distributions in averaging.

Such distributions naturally occur in quantum mechanics, not classical statistics.

The claim that weak values are purely statistical is incorrect.

Abstract

The authors of a recent paper [Phys. Rev. Lett. 113, 120404 (2014)] suggest that "weak values are not inherently quantum but rather a purely statistical feature of pre- and postselection with disturbance". We argue that this claim is erroneous, since such values require averaging with distributions which change sign. This type of averaging arises naturally in quantum mechanics, but may not occur in classical statistics.