Measurement-induced decoherence and information in double-slit interference

TL;DR

This paper models the double-slit experiment to show how measurement causes decoherence and loss of interference, linking information gain to the destruction of quantum interference in a way accessible to students.

Contribution

It provides a simplified, educational model connecting measurement-induced decoherence with information gain in the double-slit experiment.

Findings

Loss of interference correlates with information gain.

Measurement causes dephasing and decoherence.

Model accessible to graduate and senior undergraduate students.

Abstract

The double slit experiment provides a classic example of both interference and the effect of observation in quantum physics. When particles are sent individually through a pair of slits, a wave-like interference pattern develops, but no such interference is found when one observes which "path" the particles take. We present a model of interference, dephasing, and measurement-induced decoherence in a one-dimensional version of the double-slit experiment. Using this model, we demonstrate how the loss of interference in the system is correlated with the information gain by the measuring apparatus/observer. In doing so, we give a modern account of measurement in this paradigmatic example of quantum physics that is accessible to students taking quantum mechanics at the graduate or senior undergraduate levels.