Measurements of Trap Loss Rate Coefficients and Trap Characteristics of a Rubidium Magneto-Optical Trap.

王贵平 Wang Guiping, 冀炜邦 Ji Weibang, Jie Ma +3 more

Sourav Dutta, Adeel Altaf, John Lorenz +2 more

Seunghyun Lee, K. Ravi, S. A. Rangwala

We measure the collision-rate coefficient between laser-cooled rubidium (Rb) atoms in a magneto-optical trap (MOT) and optically dark Rb${}^{+}$ ions in an overlapping Paul trap. In such a mixture, the ions are created from the MOT atoms and allowed to accumulate in the ion trap, which results in a significant reduction in the number of steady-state MOT atoms. A theoretical rate-equation model is developed to describe the evolution of the MOT atom number due to ionization and ion-atom collisions, and we derive an expression for the ion-atom collision-rate coefficient. The loss of MOT atoms is studied systematically by sequentially switching on the various mechanisms in the experiment. Combining the measurements with the model allows the direct determination of the ion-atom collision-rate coefficient. Finally, the scope of the experimental technique developed here is discussed.

Wei Wen Yu, Brad Crochet, Gregory Carson +1 more

S. Supakar, Vivek Singh, Vibhuti Bhushan Tiwari +1 more

In this work, the UHV background pressure as low as 1.1×10−10 Torr has been measured using the loss rate characteristics of a vapor-loaded magneto-optical trap (MOT) formed on an atom chip in a UHV chamber. The loss rate due to non-rubidium (Rb) gases in the background in the chamber has been estimated by operating the MOT in low cooling beam intensities and low Rb pressure regimes simultaneously. Using this approach, we minimized the contributions of the intra-trap collisions as well as background MOT species collisions to the measured trap loss rate in our setup. These results can be useful for development of cold-atom based UHV pressure standards.

Gregory Carson, Tyler McCleery, Dwana King +1 more