Are weak measurements really necessary for Leggett-Garg type measurements?

TL;DR

This paper challenges the common belief that weak measurements are necessary for non-invasive measurements in Leggett-Garg tests, demonstrating that strong measurements can be equally effective and resource-efficient.

Contribution

It provides a simple error analysis showing strong measurements can replace weak ones for Leggett-Garg inequalities, countering the prevalent assumption.

Findings

Strong measurements can be used for Leggett-Garg tests with comparable error levels.

Weak measurements are not necessarily more non-invasive than strong measurements.

Strong measurements may be more resource-efficient than weak measurements.

Abstract

Leggett-Garg inequalities are an important milestone in our quest to bridge the classical-quantum divide. An experimental investigation of these inequalities requires the so called \emph{non-invasive measurements}(NIM). It has become popular to invoke weak measurements as the means of realising NIMs to very good approximation, because of their allegedly low disturbance of systems under measurement. In this note, this is shown to be a myth; it is shown, by simple estimates of errors, that for comparable levels of statistical errors, even the strong or projective measurements can be used. In fact, it is shown that resource-wise, strong measurements are even preferable.