Two-dimensional motion of an impurity under dynamic light-induced dipole forces in an atomic subwavelength array

TL;DR

This paper investigates the complex two-dimensional motion of an impurity in a subwavelength atomic array influenced by light-induced dipole forces, revealing stable orbits and polaron-like excitations through semi-classical analysis.

Contribution

It introduces a semi-classical model for impurity dynamics in atomic arrays, highlighting stable orbit formation and impurity-lattice interactions not previously explored.

Findings

Impurity can sustain long-lived quasi-stable orbits within the array.

The impurity's trajectory depends strongly on the atomic transition dipole moment.

Lattice atom motional degrees of freedom lead to polaron-like excitations.

Abstract

Long-range dipole-dipole interactions in subwavelength arrays of quantum emitters involve virtual photon exchange processes that impart forces on the emitters due to the imposed photon recoil. We perform a semi-classical analysis of the dynamics of an impurity allowed to freely move through a subwavelength array of atoms in different parameter regimes. We numerically solve the coupled set of equations between motional and spin degrees of freedom to elucidate the possible impurity trajectories realizable in this system. We find that the impurity can maintain quasi-stable orbits within the plaquette for long times. The regions through which these orbits pass are strongly dependent on the chosen atomic transition dipole moment. We further provide intuition for our findings based on a simplified model, where the lattice dynamics is adiabatically eliminated. As a final point of analysis, we also take the motional degrees of freedom of the lattice atoms into account, and study the polaron-like excitation induced in the kinetic state of the lattice by the impurity.