# Coexistence of full which-path information and interference in Wheelers delayed choice experiment with photons

## TL;DR

This paper presents a computer simulation model of Wheeler's delayed choice experiment that reproduces quantum results using a particle-only approach, challenging the traditional interpretation of wave-particle complementarity.

## Contribution

The simulation demonstrates that full which-path information and interference can coexist, questioning the universality of the complementarity relation in quantum mechanics.

## Key findings

- Simulation reproduces quantum averages without quantum theory
- Full WPI achieved with zero interference visibility
- Challenges the traditional interpretation of complementarity

## Abstract

We present a computer simulation model that is a one-to-one copy of an experimental realization of Wheeler's delayed choice experiment that employs a single photon source and a Mach-Zehnder interferometer composed of a 50/50 input beam splitter and a variable output beam splitter with adjustable reflection coefficient $R$ (V. Jacques {\sl et al.}, Phys. Rev. Lett. 100, 220402 (2008)). For $0\le R\le 0.5$, experimentally measured values of the interference visibility $V$ and the path distinguishability $D$, a parameter quantifying the which-path information WPI, are found to fulfill the complementary relation $V^2+D^2\le 1$, thereby allowing to obtain partial WPI while keeping interference with limited visibility. The simulation model that is solely based on experimental facts, that satisfies Einstein's criterion of local causality and that does not rely on any concept of quantum theory or of probability theory, reproduces quantitatively the averages calculated from quantum theory. Our results prove that it is possible to give a particle-only description of the experiment, that one can have full WPI even if D=0, V=1 and therefore that the relation $V^2+D^2\le 1$ cannot be regarded as quantifying the notion of complementarity.