This thesis explores interference effects in classical and quantum optics through two independent theoretical frameworks, establishing electromagnetic interference as a unifying and physically measurable mechanism governing light-matter interactions. Both frameworks demonstrate how reflection-induced phase shifts and field coherence jointly govern measurable observables, providing a rigorous theoretical foundation for high-precision measurement, innovative sensing, and emerging applications in quantum information science.
In the classical optics framework, reflectivity serves as the primary observable linking material parameters to changes in the reflected field. Using Fabry-Perot cavities, we demonstrate that phase-coherent back-reflection from target molecules, without any direct contact with the resonator, modifies the minima of the reflection spectrum, enabling remote, label-free detection while preserving cavity stability.
In the quantum optics framework, we recast the Jaynes-Cummings model from a microscopic, first-principles derivation rather than a phenomenological ansatz. This yields quantitative predictions for the spontaneous emission rate across a continuous range of cavity geometries, showing that the cavity emission rate equals the free-space rate in conventional resonators, and exceeds it by a factor of approximately 20,000 in plasmonic nanocavities. For multiple emitters, the framework captures ultralong-range dipole-dipole interactions mediated by a mirror, with tunable superradiant and subradiant decay rates. This analysis further reveals a spatial-temporal correspondence between the collective decay rate and the temporal coherence of the emitted field, providing a unified interpretive framework for collective light-matter coupling, and opens a direct route to non-invasive distance sensing in nanophotonic systems.
