Creating and trapping molecular negative ions in a Penning ion trap

Ke Yao, R. Schuch

Daniel J. Larson, C J Edge, Randolph E. Elmquist +2 more

Photodetachment experiments with atomic and molecular negative ions have been carried out using a Penning ion trap. The experiments provide new information about photodetachment in the presence of a static magnetic field and about photodetachment in the presence of a strong laser field.

Timo A. Nieminen

Martijn A. van Eijkelenborg, M.E.M Storkey, D. M. Segal +1 more

We have trapped and sympathetically cooled the molecular ions ${\mathrm{HCO}}^{+}$ and ${\mathrm{N}}_{2}{\mathrm{H}}^{+}$ in a Penning trap. Through their Coulomb interaction with laser-cooled ${\mathrm{Mg}}^{+}$ ions the molecules were sympathetically cooled to cryogenic temperatures. We identify the molecules through a measurement of their characteristic mass-dependent breathing mode frequencies. From a measurement of the temperature of the ${\mathrm{Mg}}^{+}$ ions we estimate that the final temperature of the sympathetically cooled molecules is 4 K.

D. R. Crick

The long term aim of this work is to study the suitability of using laser cooled Ca+ ions in Penning traps as the basic components of a quantum computer. A great deal of progress in the field of quantum computing has been made in recent years with laser cooled ions stored in radio frequency ion traps. Building a useful quantum computer with trapped ions is however extremely challenging. Penning traps offer some possible benefits over radio frequency traps. They also create some additional difficulties. The potential advantages and disadvantages of Penning traps are discussed throughout the thesis. We show that we are able to overcome the problems associated with laser cooling in Penning traps, and have trapped single ions for extended periods of time. Pairs of Ca+ ions have been aligned along the axis of a Penning trap, and have been optically resolved. A novel Penning trap array based on PCB boards has been developed. A prototype was built and tested, along with the electronics required to shuttle ions between different sub-traps. Ions have been shuttled a distance of 10 mm in 2.5 μs. A return trip efficiency of up to 75% was seen. A quantum effect – J-state mixing caused by large magnetic fields – has been observed for the first time in single atomic ions. The magnetic field causes a forbidden [Delta]J = 2 transition to become weakly allowed. This effect is of general interest in atomic physics, and is also very relevant for quantum computation studies. A quantitative prediction of the magnitude of the J-mixing effect has been derived theoretically. This is compared to experimental data, and is found to be in excellent qualitative and good quantitative agreement.