Time dependence of few-body Förster interactions among ultracold Rydberg atoms

Abstract

Rubidium Rydberg atoms in either |mj|-sublevel of the 36p 3/2 state can exchange energy via Stark-tuned Förster resonances, including two-, three-, and four-body dipole-dipole interactions. Three-body interactions of this type were first reported and categorized by Faoro, et al. [Nat. Commun. 6, 8173 (2015)] and their Borromean nature was confirmed by Tretyakov, et al. [Phys. Rev. Lett. 119, 173402 (2017)]. We report the time dependence of the N -body Förster resonance N × 36p 3/2,|m j |=1/2 → 36s 1/2 + 37s 1/2 + (N − 2) × 36p 3/2,|m j |=3/2 , for N = 2, 3, and 4, by measuring the fraction of initially excited atoms that end up in the 37s 1/2 state as a function of time. The essential features of these interactions are captured in an analytical model that includes only the many-body matrix elements and neighboring atom distribution. A more sophisticated simulation reveals the importance of beyond-nearest-neighbor interactions and of always-resonant interactions.