Rydberg Stark Deceleration

Rydberg states of atoms and molecules exhibit very large electric dipole moments, which scale as the square of the principal quantum number n, and can be as large as 3000 Debye at n=30. Through these dipole moments, the atoms and molecules interact strongly with electric fields, allowing one to manipulate their motion. To this end, we generate strong, time-dependent electric-field gradients, with which we apply forces on Rydberg atoms and molecules [1]. When the molecules are entrained in cold supersonic beams, the forces can be used to slow down the beams, the result being a slow beam of translationally cold atoms or molecules. We call this deceleration technique Rydberg-Stark deceleration. It is a universal technique to generate cold atomic or molecular samples because all atoms and molecules have Rydberg states.

In previous work performed in our laboratory, we used this technique to develop a range of atom- and molecule-optics devices, including Rydberg-atom and -molecule accelerators and decelerators [1], mirrors [2],  traps [3],  and deflectors [4] and used these devices in experiments on atomic and molecular hydrogen, argon and helium. Once trapped, the Rydberg atoms and molecules can be used in spectroscopic and collisional experiments, and to study the decay of Rydberg-atoms induced by blackbody radiation over long timescales [5].

Current work focuses on the deceleration and trapping of metastable (1s)(2s) ³S₁ helium atom using a Rydberg-Stark decelerator and superimposed electric and magnetic traps. Since triplet helium has a nonzero total electron spin, it interacts with magnetic fields. The atoms, initially moving in supersonic beams at speeds of about 500 m/s, are excited to a Rydberg-Stark state, decelerated using Rydberg-Stark deceleration, deflected and stored in an off-axis electrostatic trap that is superimposed on a magnetic trap. Once they decay from the Rydberg state back to the metastable state they remain confined in the magnetic trap. This cycle can be repeated, thereby increasing the density of metastable in the magnetic trap. Next to studying the dynamics of the repeated trap-loading process with triplet helium, applying the methods to other species will allow us to study particle interactions in dense cold samples of species that cannot be trapped with current techniques.