Delayed Choice, Complementarity, Entanglement and Measurement

TL;DR

This paper explains delayed choice quantum experiments, including those with entangled particles, without invoking backward-in-time effects, using the Convivial Solipsism interpretation to clarify measurement and wave function collapse.

Contribution

It provides a simple, non-retrocausal explanation for delayed choice experiments and discusses how Convivial Solipsism clarifies wave function collapse in entangled systems.

Findings

Delayed choice experiments can be explained without backward-in-time effects.

Convivial Solipsism offers a natural framework for understanding wave function collapse.

Entangled particle experiments pose additional interpretative challenges.

Abstract

It is well known that Wheeler proposed several delayed choice experiments in order to show the impossibility to speak of the way a quantum system behaves before being detected. In a double-slit experiment, when do photons decide to travel by one way or by two ways? Delayed choice experiments seem to indicate that, strangely, it is possible to change the decision of the photons until the very last moment before they are detected. This led Wheeler to his famous sentence: No elementary quantum phenomenon is a phenomenon until it is a registered phenomenon, brought to a close by an irreversible act of amplification. Nevertheless some authors wrote that backward in time effects were needed to explain these results. I will show that in delayed choice experiments involving only one particle, a simple explanation is possible without invoking any backward in time effect. Delayed choice experiments involving entangled particles such as the so called quantum eraser can also be explained without invoking any backward in time effect but I will argue that these experiments cannot be accounted for so simply because they rise the whole problem of knowing what a measurement and a collapse are. A previously presented interpretation, Convivial Solipsism, is a natural framework for giving a simple explanation of these delayed choice experiments with entangled particles. In this paper, I show how Convivial Solipsism helps clarifying the puzzling questions raised by the collapse of the wave function of entangled systems.