Two-body Förster resonance involving RbnDstates in a quasi-electrostatic trap

Abstract

Many-body effects have been both a source of motivationas well as an explanation for experiments involving Rydbergatoms in ultracold trapped alkali gases since the beginningof this research field. Therefore, it is not surprising that thefirst seminal ultracold Rydberg results were interpreted asa manifestation of many-body interactions in the late 1990s[1,2]. Over the past ten years, several experimental resultsinvolving either Forster resonance or Rydberg atom blockade¨processes have been reported in the literature as a clearmanifestation of many-body effects. Such works can be foundin several recent reviews [3–7]. Most of the experimentalresults attributed to many-body effects in cold Rydberg atomseither involve the observation of excitation saturation effectsor linewidth broadening in atomic samples held in a magneto-optical trap. Such association is done by comparing the ex-perimental observations to complex theoretical models. Thesetheoretical models are cumbersome due to the complexity ofincluding many bodies. Thus, many-body models often relyon approximations to address the calculation, and a standardapproximation involves breaking the problem into a series oftwo-body pieces. Therefore, the majority of the many-bodymodels are based on the summation of Rydberg atom pairinteractions [8,9], which make them computationally intense,and usually are limited to about 20 atoms.It is important to point out that Forster resonance exper-¨iments are usually carried out in a magneto-optical trap at amaximumdensityontheorderof3 ×10