Orthogonal flexible Rydberg aggregates

We study the link between atomic motion and exciton transport in flexible Rydberg aggregates, assemblies of highly excited light alkali atoms, for which motion due to dipole-dipole interaction becomes relevant. In two one-dimensional atom chains crossing at a right angle adiabatic exciton transport is affected by a conical intersection of excitonic energy surfaces, which induces controllable non-adiabatic effects. A joint exciton/motion pulse that is initially governed by a single energy surface is coherently split into two modes after crossing the intersection. The modes induce strongly different atomic motion, leading to clear signatures of non-adiabatic effects in atomic density profiles. We have shown how this scenario can be exploited as an exciton switch, controlling direction and coherence properties of the joint pulse on the second of the chains [K.~Leonhardt {\it et al.}, Phys.~Rev.~Lett. {\bf 113} 223001 (2014)]. In this article we discuss the underlying complex dynamics in detail, characterise the switch and derive our isotropic interaction model from a realistic anisotropic one with the addition of a magnetic bias field.