Chaotic walking and fractal scattering of atoms in a tilted optical lattice

TL;DR

This paper demonstrates theoretically and numerically that cold atoms in a tilted optical lattice exhibit chaotic walking and fractal scattering, characterized by self-similar structures and non-exponential scattering time distributions.

Contribution

It introduces the concept of chaotic walking of atoms in a tilted optical lattice and analyzes its fractal scattering properties using semiclassical and Hamiltonian models.

Findings

Chaotic atomic motion causes fractal-like scattering patterns.

Scattering time distribution exhibits a power-law decay.

Atomic dipole-moment behavior influences chaotic walking.

Abstract

Chaotic walking of cold atoms in a tilted optical lattice, created by two counter propagating running waves with an additional external field, is demonstrated theoretically and numerically in the semiclassical and Hamiltonian approximations. The effect consists in random-like changing the direction of atomic motion in a rigid lattice under the influence of a constant force due to a specific behavior of the atomic dipole-moment component that changes abruptly in a random-like manner while atoms cross standing-wave nodes. Chaotic walking generates a fractal-like scattering of atoms that manifests itself in a self-similar structure of the scattering function in the atom-field detuning, position and momentum spaces. The probability distribution function of the scattering time is shown to decay in a non-exponential way with a power-law tail.