A model for charge transfer in ultracold Rydberg ground-state atomic collisions

Abstract

In excited molecules, the interaction between the covalent Rydberg and ion-pair channels forms a unique class of excited Rydberg states, in which the infinite manifold of vibrational levels are the equivalent of atomic Rydberg states with a heavy electron mass. Production of the ion pair states usually requires excitation through one or several interacting Rydberg states; these interacting channels are pathways for loss of flux, diminishing the rate of ion pair production. Here, we develop an analytical, asymptotic charge transfer model for the interaction between ultracold Rydberg molecular states, and employ this method to demonstrate the utility of off-resonant field control over the ion pair formation, with near unity efficiency.

Data on inelastic processes in low-energy potassium-hydrogen and rubidium-hydrogen collisions

“…The non-adiabatic nuclear dynamical calculations are carried out by means of the multichannel model approach for each set of non-adiabatic parameters obtained from the electronic structure calculations by means of two independent dynamical codes. Very recently, Markson & Sadeghpour (2016) have developed a model approach that could be applied to systems such as those studied here, and future comparisons would be of interest.…”

Formation of ultracold ion pairs through long-range Rydberg molecules

“…This photoinduced charge-transfer process bears features of a harpoon reaction, where the Rydberg atom captures the ground-state atom by donating its electron to the neutral and a more strongly bound ion pair is formed. Note that the direct photoassociation into an electronic state with ion-pair character is only possible at much shorter internuclear distances than considered here, where covalent and ionic molecular states are strongly mixed [16,17].…”

“…At short internuclear distances, the electronic configuration of the ion-pair state mixes with excited electronic configurations of the neutral-parent dimer, possibly leading to strong perturbations of the electronic structure. Previous excitation schemes of molecular heavy-Rydberg states relied on such short-range mixings to excite the ion-pair states from the ground state of the parent molecule in a supersonic molecular beam (see, e.g., [14,15]) or in ultracold gases [16,17]. However, these schemes have not yet yielded dense samples of heavy-Rydberg molecules, mostly because the exploited perturbations are weak and their accurate prediction is a significant challenge for current quantumchemical methods.…”

Ultracold Rydberg molecules

“…The extreme nature of ultralong-range molecules can give insights into quantum chemistry, as was studied in coherent photodissoaction and photoassociation with rotary echo techniques 100 . Butterfly molecules 39 , by virtue or their favorable Franck-Condon overlap with low-lying Rydberg states, can be utilized to populate vibrationally bound heavy Rydberg systems, i.e., ion-pairs of ultracold atoms 101 , 102 .…”