Quantum optical coherence theory based on Feynman's path integral

TL;DR

This paper introduces a novel quantum optical coherence theory using Feynman's path integral, offering better physical insights and predictions that challenge classical models, with implications for understanding photon nature.

Contribution

It develops and reviews a quantum optical coherence framework based on Feynman's path integral, connecting mathematical calculations with physical interpretations.

Findings

Classical electric field model for thermal light may be inaccurate.

Two-photon bunching and Hong-Ou-Mandel effects are explained by two-photon interference.

Path integral approach enhances understanding of light coherence and photon identity.

Abstract

Compared to classical optical coherence theory based on Maxwell's electromagnetic theory and Glauber's quantum optical coherence theory based on matrix mechanics formulation of quantum mechanics, quantum optical coherence theory based on Feynman's path integral formulation of quantum mechanics provides a novel tool to study optical coherence. It has the advantage of understanding the connection between mathematical calculations and physical interpretations better. Quantum optical coherence theory based on Feynman's path integral is introduced and reviewed in this paper. Based on the results of transient first-order interference of two independent light beams, it is predicted that the classical model for electric field of thermal light introduced by classical optical textbooks may not be accurate. The physics of two-photon bunching of thermal light and Hong-Ou-Mandel dip of entangled photon pairs is the same, which can be interpreted by constructive and destructive two-photon interference, respectively. Quantum optical coherence theory based on Feynman's path integral is helpful to understand the coherence properties of light, which may eventually lead us to the answer of the question: what is a photon?