Subtraction of ``accidentals'' and the validity of Bell tests

TL;DR

This paper critically examines the data adjustment process in Bell tests, highlighting that the common practice of subtracting accidentals lacks proper justification and may undermine the validity of experimental conclusions about quantum nonlocality.

Contribution

It provides a detailed critique of the data correction methods in Bell experiments and advocates for re-evaluating the evidence considering known loopholes and local realist models.

Findings

Subtraction of accidentals can inflate Bell violation statistics by up to 60%.

A well-known realist model fits unadjusted data without violations.

Many Bell experiments may have used invalid data correction practices.

Abstract

In some key Bell experiments, including two of the well-known ones by Alain Aspect, 1981-2, it is only after the subtraction of ``accidentals'' from the coincidence counts that we get violations of Bell tests. The data adjustment, producing increases of up to 60% in the test statistics, has never been adequately justified. Few published experiments give sufficient information for the reader to make a fair assessment. There is a straightforward and well known realist model that fits the unadjusted data very well. In this paper, the logic of this realist model and the reasoning used by experimenters in justification of the data adjustment are discussed. It is concluded that the evidence from all Bell experiments is in urgent need of re-assessment, in the light of all the known ``loopholes''. Invalid Bell tests have frequently been used, neglecting improved ones derived by Clauser and Horne in 1974. ``Local causal'' explanations for the observations have been wrongfully neglected.