Dipole-dipole interaction between orthogonal dipole moments in time-dependent geometries

TL;DR

This paper investigates how dipole-dipole interactions with orthogonal dipole moments in two-atom systems are affected by varying geometries, comparing averaging methods to understand their impact on the coupling effects.

Contribution

It introduces and compares two averaging methods for geometries in systems with orthogonal dipole coupling, revealing the robustness of this interaction under different conditions.

Findings

Orthogonal dipole coupling persists after averaging over geometries.

Different averaging methods yield qualitatively different results.

Low-dimensional systems are promising models for observing these effects.

Abstract

In two nearby atoms, the dipole-dipole interaction can couple transitions with orthogonal dipole moments. This orthogonal coupling accounts for a number of interesting effects, but strongly depends on the geometry of the setup. Here, we discuss several setups of interest where the geometry is not fixed, such as particles in a trap or gases, by averaging over different sets of geometries. Two averaging methods are compared. In the first method, it is assumed that the internal electronic evolution is much faster than the change of geometry, whereas in the second, it is vice versa. We find that the orthogonal coupling typically survives even extensive averaging over different geometries, albeit with qualitatively different results for the two averaging methods. Typically, one- and two-dimensional averaging ranges modelling, e.g., low-dimensional gases, turn out to be the most promising model systems.