Modular values and weak values of quantum observables

TL;DR

This paper introduces modular values of quantum observables, linking them to weak values, and extends the concept to multi-qubit systems to explain recent experiments involving various coupling strengths.

Contribution

It presents the concept of modular values, generalizes it for multi-qubit systems, and clarifies their relation to weak values and experimental results.

Findings

Modular values are similar to weak values but apply to any coupling strength.

The generalization to multi-qubit meters explains recent experimental observations.

Provides a new framework for understanding quantum measurements with different coupling regimes.

Abstract

The concept of a modular value of an observable of a pre- and post-selected quantum system is introduced. It is similar in form and in some cases has a close connection to the weak value of an observable, but instead of describing an effective interaction when the coupling is weak, it describes a coupling of any strength but only to qubit meters. The generalization of the concept for a coupling of a composite system to a multi-qubit meter provides an explanation of some current experiments.