Delocalization of ultracold atoms in a disordered potential due to light scattering

TL;DR

This study demonstrates that even minimal light scattering from a measurement process can delocalize ultracold atoms in a disordered potential, challenging the robustness of Anderson localization.

Contribution

It introduces a numerical approach combining a Lindblad master equation and Monte Carlo techniques to show light scattering causes delocalization of atoms in disordered systems.

Findings

Weak photon emission destroys Anderson localization

Light scattering induces atomic delocalization

Numerical simulation confirms delocalization mechanism

Abstract

We numerically study the expansion dynamics of ultracold atoms in a one-dimensional disordered potential in the presence of a weak position measurement of the atoms. We specifically consider this position measurement to be realized by a combination of an external laser and a periodic array of optical microcavities along a waveguide. The position information is acquired through the scattering of a near-resonant laser photon into a specific eigenmode of one of the cavities. The time evolution of the atomic density in the presence of this light scattering mechanism is described within a Lindblad master equation approach, which is numerically implemented using the Monte Carlo wave function technique. We find that an arbitrarily weak rate of photon emission leads to a breakdown of Anderson localization of the atoms.