General structure of two-photon S matrix in waveguide quantum electrodynamics systems containing a local quantum system with multiple ground states

TL;DR

This paper derives the general form of the two-photon S matrix in waveguide QED systems with multiple ground states, revealing non-commutative effects and deviations from standard quantum field theory principles.

Contribution

It introduces a novel framework for the two-photon S matrix in systems with multiple ground states, highlighting non-commutative properties and differences from traditional models.

Findings

Two-photon S matrix exhibits non-commutative behavior due to multiple ground states.

Standard cluster decomposition principle does not hold in these systems.

The derived structure captures unique photon interactions in complex quantum systems.

Abstract

We present the general structure of two-photon S matrix for a waveguide coupled to a local quantum system that supports multiple ground states. The presence of the multiple ground states results in a non-commutative aspect of the system with respect to the exchange of the orders of photons. Consequently, the two-photon S matrix significantly differs from the standard form as described by the cluster decomposition principle in the quantum field theory.