Collisional picture of quantum optics with giant emitters

TL;DR

This paper extends the collisional approach in quantum optics to multiple giant emitters interacting with a bosonic field, deriving a comprehensive master equation and effective Hamiltonian for complex emitter-field systems.

Contribution

It introduces a collisional framework for many giant emitters, deriving a unified Lindblad master equation applicable to various quantum optics and waveguide-QED scenarios.

Findings

Derived a Lindblad master equation for giant atoms in waveguides.

Extended the collisional approach to multiple emitters with many coupling points.

Identified chiral contributions in the effective Hamiltonian.

Abstract

The effective description of the weak interaction between an emitter and a bosonic field as a sequence of two-body collisions provides a simple intuitive picture compared to traditional quantum optics methods as well as an effective calculation tool of the joint emitter-field dynamics. Here, this collisional approach is extended to many emitters (atoms or resonators), each generally interacting with the field at many coupling points ("giant" emitter). In the regime of negligible delays, the unitary describing each collision in particular features a contribution of a chiral origin resulting in an effective Hamiltonian. The picture is applied to derive a Lindblad master equation (ME) of a set of giant atoms coupled to a (generally chiral) waveguide field in an arbitrary white-noise Gaussian state, which condenses into a single equation and extends a variety of quantum optics and waveguide-QED MEs. The effective Hamiltonian and jump operators corresponding to a selected photodetection scheme are also worked out.