Destruction of high- n ( n∼300 ) Rydberg atoms in Rydberg-Rydberg collisions

Abstract

The destruction of high-n, n ∼ 300, strontium atoms contained in a hot atomic beam through Rydberg-Rydberg collisions is examined. The Rydberg atoms are initially created, under blockade conditions, in a localized volume and their subsequent motions lead to creation of a string of Rydberg atoms. The Rydberg atoms, however, are formed with a thermal distribution of velocities resulting in Rydberg-Rydberg collisions which lead to their destruction. The experimental data are interpreted using classical trajectory Monte Carlo techniques that simulate the excitation of the Rydberg atoms together with their subsequent motions. Using calculated collisional ionization cross sections and blockade radii, the model yields results in good agreement with experiment. The results highlight the important role collisional destruction can play when attempting to study (long-range) Rydberg-Rydberg interactions in a hot atomic beam.

The effect of orientation of Rydberg atoms on their collisional ionization cross section

“…In our calculations, V CM = 10 −4 a.u. which corresponds to the rms speed at a temperature of ∼150 K. The chosen V CM is similar to the values observed in the experiment by Dunning et al [11]. The results of our calculation were relatively unchanged for a range of velocities between 7 x 10 −5 to 2 x 10 −4 a.u which corresponds to the kinetic energies associated with a temperature range of approximately 80K to 650K.…”

“…The probability of ionization P ion , can be calculated by determining the fraction of total runs that result in ionization. The cross section σ then is given [11] by…”

“…While calculations dealing with ionizing interaction between two Rydberg atoms at rest was performed earlier [14], in this paper we study collisional ionization between two interacting Rydberg atoms that are in relative motion similar to the analysis in Ref. [11,15]. The ionization cross section in general is expected to have some dependence on the magnitude of the angular momentum as it determines the eccentricity of the orbit of the electron.…”

“…The thermal energies of Rydberg atoms can also lead to collisional ionization. This was most recently examined by Dunning et al [11]. In their work, they obtained the collisional cross sections between Rydberg atoms from classical trajectory Monte Carlo calculations and com-pared these results with that of their experiment.…”

“…The currently proposed methods [11] to decrease the collisional loss of Rydberg atoms is to either lower the temperature to increase the timescale for collisional destruction or to create the Rydberg atoms in a spaced-out manner, both of which have drawbacks. The results in this paper can provide an additional perspective into the physics of the collisional ionization with possible insight to minimize it.…”