Quantum duality: A source point of view

Abstract

Usual quantitative studies of quantum wave-particle duality employ Young's double-slit context and treat the slits approximately as ideal point sources, i.e., neglecting practical nonperfections such as slit finite width, roughness, etc. Here, we investigate the duality of a photon that is generated from genuine point sources, i.e., a pair of nonlocally entangled two-level atoms. This justifies a free-space exact spherical wave treatment. More importantly, it allows for a systematic quantitative analysis of the source effects on a quantum particle's duality property. Surprisingly, duality is found to be a conditional phenomenon depending on the photon's atomic source. It can be tuned maximum, medium, and even minimum (completely absent) by the atomic state purity through an exact Pythagorean duality source relation. Our analysis shows another way of investigating quantum duality by accounting how the single quantum object is created. The results can be tested in various practical physical systems.