Stabilizing Bohr wavepackets by electron-electron interaction

Recently, so-called Bohr wavepackets have been realized experimentally in which a radially- and angularly-localized electron wavepacket travels along a circular orbit around the nucleus. Due to the non-equidistant energies of the constituent energy eigenstates, these Bohr wavepackets disperse but can be stabilized by external electric fields. Here we investigate the possibility of stabilizing such wavepackets in helium-like doubly excited Rydberg atoms through the electron-electron interaction without the need to resort to external driving fields. Our stability analysis indicates that a non-dispersive wavepacket can be created following the previously suggested ``shape preserving'' orbit for which the exchange of angular momentum between the two electrons is suppressed. The important role of electron-electron correlations in this stabilization mechanism is discussed.