Weak value amplification: a view from quantum estimation theory that highlights what it is and what isn't

TL;DR

This paper clarifies the capabilities and limitations of weak value amplification (WVA) in quantum estimation, showing it cannot surpass fundamental quantum limits but can improve sensitivity against technical noise.

Contribution

It provides a quantum estimation theory perspective on WVA, delineating what advantages it offers and its fundamental constraints.

Findings

WVA does not surpass quantum sensitivity limits.

WVA enhances sensitivity limited by technical noise.

WVA is straightforward and accessible for practical detection improvements.

Abstract

Weak value amplification (WVA) is a concept that has been extensively used in a myriad of applications with the aim of rendering measurable tiny changes of a variable of interest. In spite of this, there is still an on-going debate about its true nature and whether is really needed for achieving high sensitivity. Here we aim at solving the puzzle, using some basic concepts from quantum estimation theory, highlighting what the use of the WVA concept can offer and what it can not. While WVA cannot be used to go beyond some fundamental sensitivity limits that arise from considering the full nature of the quantum states, WVA can notwithstanding enhance the sensitivity of real detection schemes that are limited by many other things apart from the quantum nature of the states involved, i.e. technical noise. Importantly, it can do that in a straightforward and easily accessible manner.