While the theoretical studies in waveguide quantum electrodynamics predominate with single-photon and two-photon Fock state (photon number states) input, the experiments are primarily carried out using a faint coherent light. We create a theoretical toolbox to compare and contrast linear and nonlinear light scattering by a two-level or a three-level emitter embedded in an open waveguide carrying Fock state or coherent state inputs. We identify rules to compare light transport properties, the Kerr, and cross-Kerr nonlinearities of the medium for the two types of inputs. A generalized description of the Kerr and cross-Kerr effect for different types of inputs is formulated to compare the Kerr and cross-Kerr nonlinearity between two photons in these models.
@article{arxiv.2209.03418,
title = {Single photons versus coherent state input in waveguide quantum electrodynamics: light scattering, Kerr and cross-Kerr effect},
author = {Athul Vinu and Dibyendu Roy},
journal= {arXiv preprint arXiv:2209.03418},
year = {2023}
}