Model-Independent Measurement of the Excited Fraction In a Magneto-Optical Trap

In many experiments involving a magneto-optical trap (MOT) it is of great importance to know the fraction of atoms placed in an excited state due to the trapping process. Generally speaking, researchers have had to use overly simplistic and untested models to estimate this fraction. In this work, the excited fractions of 87Rb atoms in a MOT are directly measured using a charge transfer technique, for a range of MOT parameters. Simple models are then fit to the measured fractions. Using the results of this work, the excited fraction of 87Rb atoms trapped in a MOT can be accurately estimated with knowledge of only the trapping laser intensity and detuning. The results are, at most, only weakly dependent on other MOT parameters

Measurement of Population Dynamics In Stimulated Raman Adiabatic Passage

The temporal evolution of populations has been directly measured for a three-level ladder system undergoing coherent excitation by stimulated Raman adiabatic passage (STIRAP). The measurement technique makes use of charge transfer as diagnostic. The method is model independent and has a temporal resolution of a few nanoseconds. The temporal evolution is measured for several values of the delay between the pump and Stokes laser pulses that are part of the STIRAP excitation scheme. The corresponding quantum Liouville equations are solved and the results of the calculations are compared with experiment

MOTRIMS as a generalized probe of AMO processes

Magneto-optical trap recoil ion momentum spectroscopy (MOTRIMS) is one of the newest offshoots of the generalized TRIMS approach to ion–atom collisions. By using lasers instead of the more usual supersonic expansion to cool the target, MOTRIMS has demonstrated two distinct advantages over conventional TRIMS. The first is better resolution, now limited by detectors instead of target temperature. The second is its suitability for use in the study of laser-excited targets. In this presentation we will present a third advantage: The use of MOTRIMS as a general-purpose probe of AMO processes in cold atomic clouds of atoms and molecules. Specifically, the projectile ion beam can be used as a probe of processes as diverse as target dressing by femtosecond optical pulses, photo-association (laser-assisted cold collisions) photo-ionization, and electromagnetically-induced transparency. We will present data for the processes we have investigated, and speculations on what we expect to see for the processes we plan to investigate in the future

Differential charge-transfer cross sections for Na +^{+} with Rb collisions at low energies

We report on a theoretical and experimental study of state-selective differential single-electron transfer cross sections between Na$^{+}$ ions and Rb(5s,5p) atoms at collision energies of 2, 5, and 7 keV. A two-center multichannel semiclassical impact parameter close-coupling method with straight-line trajectories was used to obtain single-electron capture amplitudes. By combining with the eikonal approximation, we calculated the angular differential cross sections. These results are compared to the experimental data obtained with Rb targets cooled in a magnetic optical trap. It is shown that there is generally a good agreement between the present calculations and the experiments. In spite of the higher resolution offered from the cold target, the rapid oscillations in the differential cross sections are not resolved by the experiments