Optical Causal Structure Measurement
Jincheng Zhang
Abstract
The measurement of causal relationships within an optical field is a fundamental challenge that bridges quantum optics, photonics, and the theory of causality. This paper proposes a systematic framework for identifying and quantifying the causal structure between discrete optical events in a complex light network. Central to the approach is the construction of a causal matrix C_{ij} that represents the probability of event i causing event j, conditioned on the measurement of photon correlations, time‑stamping, and spatial mode overlap. By exploiting high‑resolution detectors and engineered photonic pathways, the framework can resolve causality in real time, even when multiple photons interfere within integrated photonic circuits. The potential for uncovering deep causal links in photonic systems suggests a pathway to Nobel‑level discoveries, unifying the physics of light with the emerging discipline of causal inference.