Weak interference in the high-signal regime

TL;DR

This paper explores the potential of using interference effects in high-signal regimes to extract information about physical systems, broadening the applicability of weak measurement techniques beyond severely depleted signals.

Contribution

It introduces the concept of weak interference, showing how interference phenomena can be used for information extraction without severe signal loss, unlike traditional weak amplification.

Findings

Weak interference allows information extraction in high-signal regimes.

Weak value concept becomes less useful in this high-signal context.

Interference-based methods can extend weak measurement applications.

Abstract

Weak amplification is a signal enhancement technique which is used to measure tiny changes that otherwise cannot be determined because of technical limitations. It is based on the existence of a special type of interaction which couples a property of a system, i.e., polarization or which-path information, with a separate degree of freedom, i.e., transverse position or frequency. Unfortunately, the weak amplification process is generally accompanied by severe losses of the detected signal, which limits the applicability of the weak amplification concept. However, we will show here that since the weak measurement concept is essentially an interference phenomena, it should be possible to use the degree of interference to get relevant information about the physical system under study in a more general scenario, where the signal is not severely depleted (high-signal regime). This can widen the range of systems where the weak measurement concept can be applied. In this scenario, which can be called generally weak interference, the idea of weak value does not convey any useful information.