J. E. Wells

Evidence of sympathetic cooling of Na+ ions by a Na magneto-optical trap in a hybrid trap

A hybrid ion-neutral trap provides an ideal system to study collisional dynamics between ions and neutrals. This system provides a general cooling method that can be applied to optically inaccessible species and can also potentially cool internal degrees of freedom. The long range polarization potentials (

Ion-neutral-atom sympathetic cooling in a hybrid linear rf Paul and magneto-optical trap

V\propto-\alpha/r^4

Loading a Linear Paul Trap to Saturation from a Magneto-Optical Trap

) between ions and neutrals result in large scattering cross sections at cold temperatures, making the hybrid trap a favorable system for efficient sympathetic cooling of ions by collisions with neutral atoms. We present experimental evidence of sympathetic cooling in a hybrid trap of \ce{Na+} ions, which are closed shell and therefore do not have a laser induced atomic transition, by equal mass cold Na atoms in a magneto-optical trap (MOT).

Measurement of the low-energy Na + − Na total collision rate in an ion-neutral hybrid trap

Long range polarization forces between ions and neutral atoms result in large elastic scattering cross sections, e.g., 10^6 a.u. for Na+ on Na or Ca+ on Na at cold and ultracold temperatures. This suggests that a hybrid ion-neutral trap should offer a general means for significant sympathetic cooling of atomic or molecular ions. We present SIMION 7.0 simulation results concerning the advantages and limitations of sympathetic cooling within a hybrid trap apparatus, consisting of a linear rf Paul trap concentric with a Na magneto-optical trap (MOT). This paper explores the impact of various heating mechanisms on the hybrid system and how parameters related to the MOT, Paul trap, number of ions, and ion species affect the efficiency of the sympathetic cooling.

Off-resonance energy absorption in a linear Paul trap due to mass selective resonant quenching

We present experimental measurements of the steady-state ion number in a linear Paul trap (LPT) as a function of the ion-loading rate. These measurements, taken with (a) constant Paul trap stability parameter

Simple locking of infrared and ultraviolet diode lasers to a visible laser using a LabVIEW proportional-integral-derivative controller on a Fabry-Perot signal

q

Universal nonmonotonic structure in the saturation curves of magneto-optical-trap-loaded Na + ions stored in an ion-neutral hybrid trap: Prediction and observation

, (b) constant radio-frequency (rf) amplitude, or (c) constant rf frequency, show nonlinear behavior. At the loading rates achieved in this experiment, a plot of the steady-state ion number as a function of loading rate has two regions: a monotonic rise (region I) followed by a plateau (region II). Also described are simulations and analytical theory which match the experimental results. Region I is caused by rf heating and is fundamentally due to the time dependence of the rf Paul-trap forces. We show that the time-independent pseudopotential, frequently used in the analytical investigation of trapping experiments, cannot explain region I, but explains the plateau in region II and can be used to predict the steady-state ion number in that region. An important feature of our experimental LPT is the existence of a radial cut-off

Experiments with an ion-neutral hybrid trap: cold charge-exchange collisions

\hat R_{\rm cut}

Photodetachment spectroscopy from the lowest threshold of S

that limits the ion capacity of our LPT and features prominently in the analytical and numerical analysis of our LPT-loading results. We explain the dynamical origin of

Model-independent measurements of the sodium magneto-optical trap's excited-state population

\hat R_{\rm cut}