Resolving ambiguities of the mode truncation in cavity quantum electrodynamics

This work provides the fundamental theoretical framework for few-mode cavity quantum electrodynamics by resolving the gauge ambiguities between the Coulomb gauge and the dipole gauge Hamiltonians under the photonic mode truncation. We first propose a general framework to resolve ambiguities for an arbitrary truncation in a given gauge. Then, we specifically consider the case of mode truncation, deriving gauge invariant expressions for both the Coulomb and dipole gauge Hamiltonians that naturally reduce to the commonly used single-mode Hamiltonians when considering a single-mode truncation. We finally provide the analytical and numerical results of both atomic and molecular model systems coupled to the cavity to demonstrate the validity of our theory. (C) 2022 Optica Publishing Group

Automated summary

This work provides a fundamental theoretical framework for few-mode cavity quantum electrodynamics by resolving the gauge ambiguities between the Coulomb gauge and the dipole gauge Hamiltonians under the photonic mode truncation. The study proposes a general framework to resolve ambiguities for arbitrary truncation in a given gauge, and derives gauge-invariant expressions for both the Coulomb and dipole gauge Hamiltonians specifically in the case of mode truncation. Analytical and numerical results of atomic and molecular model systems coupled to the cavity are presented to demonstrate the validity of the theory.