Wave-particle duality of broadband light

Abstract

We describe and analyse a simple experiment based on interference of thermally distributed broadband photons which demonstrates quantitatively the gradual trade-off between knowledge of the trajectory of a quantum particle and its wave-like character as expressed via the inequality V ² + K ² ≤ 1. The experiment relies upon colour-selective detection of light passing through each slit of a Young's double-slit arrangement: path information K is deduced from the overlapping bandwidths of the interfering light and the classical first-order degree of coherence, and wave information V is obtained from the fringe visibility. A classical Fourier analysis of the experiment is given which reproduces the observed interferograms.

Acknowledgments

RJR thanks the Nuffield Foundation for an undergraduate bursary (URB/01249/G) and AH thanks the University of Newcastle for a vacation studentship, during the tenure of which this work was carried out.