A graphical presentation of signal delays in the datasets of Weihs et al

TL;DR

This paper visually analyzes the timing data from Weihs et al.'s experiment, revealing two types of signal delays affecting avalanche photodiode events, and discusses their implications for Bell inequality tests.

Contribution

It introduces a graphical method to identify and distinguish two types of signal delays in photodiode datasets, offering insights into their causes and correction strategies.

Findings

Identified a ~20 ns delay caused by rapid switching of electro-optical modulators.

Detected delay variations depending on which avalanche photodiode registered the event.

Showed that correcting diode-specific delays minimally impacts Bell-CHSH inequality violations.

Abstract

A graphical presentation of the timing of avalanche photodiode events in the datasets from the experiment of Weihs et al. [Phys. Rev. Lett. 81, 5039 (1998)] makes manifest the existence of two types of signal delay: (1) The introduction of rapid switching of the input to a pair of transverse electro-optical modulators causes a delay of approximately 20 nanoseconds for a proportion of coincident avalanche photodiode events; this effect has been previously noted, but a different cause is suggested by the data as considered here. (2) There are delays that depend on in which avalanche photodiode an event occurs; this effect has also been previously noted even though it is only strongly apparent when the relative time difference between avalanche photodiode events is near the stated 0.5 nanosecond accuracy of the timestamps (but it is identifiable because of 75 picosecond resolution). The cause of the second effect is a difference between signal delays for the four avalanche photodiodes, for which correction can be made by straightforward local adjustments (with almost no effect on the degree of violation of Bell-CHSH inequalities).