Weng C Chew | Searcharxiv

arXiv2025

Quantum-Plasmonic Dynamics Modeled via a Modified Langevin Noise Formalism: Numerical Studies of Single-Photon Emission and Two-Photon Interference

Recent studies have established and rigorously validated a modified Langevin noise formalism that enables first-principles quantization of electromagnetic fields in open and dissipative environments [1,2,3]. Building on this foundation, a fully quantum-mechanical multimode Jaynes-Cummings framework has been developed and verified, providing an accurate description of atom--field interactions in lossy and radiative systems [4]. In this work, we explore the potential of this formalism for nanophotonic applications by modeling representative quantum-plasmonic dynamics. In particular, we present detailed numerical examples for (i) two-photon interference mediated by a quantum plasmonic beam splitter, and (ii) non-Markovian dynamics of an atom located in plasmonic antennas and directional control of out-coupled single-photon fields. These results demonstrate that the proposed modeling approach can be directly used to guide the design and optimization of plasmonic single-photon sources and beam-splitting structures. Moreover, the framework is broadly applicable to the analysis of linear optical components and cavity quantum electrodynamics problems in open and dissipative photonic integrated circuits.

physics.optics↗

arXiv2023

Numerical Framework for Modeling Quantum Electromagnetic Systems Involving Finite-Sized Lossy Dielectric Objects in Free Space

The modified Langevin noise formalism has been proposed for the correct charaterization of quantum electromagnetic fields in the presence of finite-sized lossy dielectric objects in free space. The main modification to the original one (also known as the Green's function approach available only for bulk inhomogeneous lossy dielectric medium) was to add fluctuating sources in reaction to the radiation loss. Consequently, a resulting electric field operator is now determined by (i) boundary-assisted and (ii) medium-assisted fields on an equal footing, which are fluctuating sources due to radiation and medium losses, respectively. However, due to the lengthy mathematical manipulation and complicated concepts, the validity of the modified Langevin noise formalism has not been clearly checked yet. In this work, we propose and develop a novel numerical framework for the modified Langevin noise formalism by exploiting computational electromagnetic methods (CEM). Specifically, we utilize the finite-element method to numerically solve plane-wave-scattering and point-source-radiation problems whose solutions are boundary-assisted and medium-assisted fields, respectively. Based on the developed numerical framework, we calculate the Purcell factor of a two-level atom inside or outside a lossy dielectric slab. It is numerically proved, for the first time, that one can retrieve the conventional expression of the spontaneous emission rate, viz., the imaginary part of the Green's function. The proposed numerical framework is particularly useful for estimating the dynamics of multi-level atoms near practical plasmonic structures or metasurfaces.

quant-ph↗