Quantitative Complementarity of Wave-Particle Duality

TL;DR

This paper presents a double-path interferometer using parametric downconversion to quantitatively analyze wave-particle duality, linking source purity, entanglement, and coherence through experimental parameters.

Contribution

It introduces a novel interferometer setup that enables precise measurement of wave-particle complementarity using entanglement and source purity relations.

Findings

Source purity is bounded by entanglement measure E as μ_s=√(1−E²)

Visibility and detector fidelity determine quantum coherence as C=V|F|

The scheme effectively investigates wave-particle duality quantitatively.

Abstract

To test the principle of complementarity and wave-particle duality quantitatively, we need a quantum composite system that can be controlled by experimental parameters. Here, we demonstrate that a double-path interferometer consisting of two parametric downconversion crystals seeded by coherent idler fields, where the generated coherent signal photons are used for quantum interference and the conjugate idler fields are used for which-path detectors with controllable fidelity, is useful for elucidating the quantitative complementarity. We show that the source purity $\mu_s$ is tightly bounded by the entanglement measure $E$ by the relation $\mu_s=\sqrt{1-E^2 }$ and the visibility $V$ and detector fidelity $F$ determine the coherence of the quantons, i.e., $C = V|F|$. The quantitative complementarity of the double-path interferometer we developed recently is explained in terms of the quanton-detector entanglement or quanton source purity that are expressed as functions of injected seed photon numbers. We further suggest that the experimental scheme utilizing two stimulated parametric downconversion processes is an ideal tool for investigating and understanding wave-particle duality and complementarity quantitatively.