Ab initio few-mode theory for quantum potential scattering problems

Understand

Few-mode models have been a cornerstone of the theoretical work in quantum optics, with the famous single-mode Jaynes-Cummings model being only the most prominent example.

• In this work, we develop ab initio few-mode theory, a framework connecting few-mode system-bath models to ab initio theory.
• We first present a method to derive exact few-mode Hamiltonians for non-interacting quantum potential scattering problems and demonstrate how to rigorously reconstruct the scattering matrix from such few-mode Hamiltonians.
• We show that upon inclusion of a background scattering contribution, an ab initio version of the well known input-output formalism is equivalent to standard scattering theory.