Li-Bang Wang

Refined determination of the muonium-deuterium 1S-2S isotope shift through improved frequency calibration of iodine lines.

Isaac Fan, 2, ∗ Chun-Yu Chang, Li-Bang Wang, 2 Simon L. Cornish, Jow-Tsong Shy, 2, 3 and Yi-Wei Liu 2, † Department of Physics, National Tsing Hua University, Hsinchu City, 30013, Taiwan (R.O.C.) Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu City, 30013, Taiwan (R.O.C.) Institute of Photonics Technology, National Tsing Hua University, Hsinchu City, 30013, Taiwan (R.O.C.) Joint Quantum Centre (JQC), Durham–Newcastle, Department of Physics, Durham University, Durham, DH1 3LE, United Kingdom

Precision saturated absorption spectroscopy of H3

In our previous work on the Lamb-dips of the ν2 fundamental band transitions of H3+, the saturated absorption spectrum was obtained by third-derivative spectroscopy using frequency modulation with an optical parametric oscillator (OPO). However, frequency modulation also caused errors in the absolute frequency determination. To solve this problem, we built a tunable offset locking system to lock the pump frequency of the OPO to an iodine-stabilized Nd:YAG laser. With this improvement, we were able to scan the OPO idler frequency precisely and obtain the saturated absorption profile using intensity modulation. Furthermore, ion concentration modulation was employed to subtract the background noise and increase the signal-to-noise ratio. To determine the absolute frequency of the idler wave, the OPO signal frequency was locked to an optical frequency comb. The absolute frequency accuracy of our spectrometer was better than 7 kHz, demonstrated by measuring the wavelength standard transition of methane at 3.39 μm. Finally, we measured 16 transitions of H3+ and our results agree very well with other precision measurements. This work successfully resolved the discrepancies between our previous measurements and other precision measurements.

Isotope-selective trapping of doubly charged Yb ions

We report isotope-selective loading and trapping of doubly ionized ytterbium into an rf quadrupole trap. Isotopically pure clouds of {sup 174}Yb{sup +} ions were first loaded into the rf trap via a multistage photoionization process. The Yb{sup 2+} ions were then produced by electron impact ionization of the trapped Yb{sup +} ions. The Yb{sup 2+} ions were subsequently detected by rf excitation of their secular motion in the trap, which led to sympathetic heating and changes in the fluorescence of the laser-cooled Yb{sup +} ions. The presence of doubly charged Yb ions was further verified by the appearance of a dark band in the center of Yb{sup +} ion cloud after electron impact ionization. We discuss the possible formation of Yb{sup 2+}H and similar compounds and the schemes for the direct optical detection of the Yb{sup 2+} ions.

Isotope selective trapping of singly and doubly charged Yb ions in an RF trap

We have successfully trapped singly and doubly ionized Ytterbium in a linear RF quadrupole trap. Ionization was accomplished with both photoionization and electron beam ionization. Co-trapping of Yb+ and Yb2+ was confirmed through electronic detection.