Cooperative eigenmodes and scattering in 1D atomic arrays

TL;DR

This paper explores how collective dipole interactions in 1D atomic arrays influence optical responses, revealing controllable superradiant and subradiant modes, and drawing parallels to cavity QED phenomena.

Contribution

It introduces a classical coupled dipole model to analyze eigenmodes in 1D atomic arrays, highlighting mode control via polarization and geometry, and connecting to cavity QED analogs.

Findings

Identification of superradiant and subradiant eigenmodes

Observation of Fano-like interferences between modes

Eigenmodes with decay rates similar to single atoms in cavities

Abstract

Collective coupling between dipoles can dramatically modify the optical response of a medium. Such effects depend strongly on the geometry of the medium and the polarization of the light. Using a classical coupled dipole model, here we investigate the simplest case of one dimensional (1D) arrays of interacting atomic dipoles driven by a weak laser field. Changing the polarization and direction of the driving field allows us to separately address superradiant, subradiant, red-shifted, and blue-shifted eigenmodes, as well as observe strong Fano-like interferences between different modes. The cooperative eigenvectors can be characterized by the phase difference between nearest neighbor dipoles, ranging from all oscillating in phase to all oscillating out of phase with their nearest neighbors. Investigating the eigenvalue behavior as a function of atom number and lattice spacing, we find that certain eigenmodes of an infinite atomic chain have the same decay rate as a single atom between two mirrors. The effects we observe provide a framework for collective control of the optical response of a medium, giving insight into the behavior of more complicated geometries, as well as providing further evidence for the dipolar analog of cavity QED.