Femtosecond Laser Cooling of Trapped Ions

S. Removille, Romain Dubessy, B. Dubost +5 more

This paper reports on trapping and laser cooling of singly ionized strontium ions in a linear Paul trap. We describe the loading technique based on two-photon absorption of femtosecond pulses at a wavelength of 431 nm and we compare this technique to electron-bombardment ionization. We perform Doppler cooling of the ions in the few-ions regime as well as in the case of large clouds. The analysis of the fluorescence spectra and direct imaging of the cloud allows us to identify the Coulomb-crystal regime. These experiments open the way to the use of a large cold trapped-ion cloud as a medium for quantum optics and quantum information experiments.

Ferdinand Schmidt‐Kaler, Jürgen Eschner, R. Blatt +3 more

Richard Claude Thompson

We present the results of some simulations of the laser cooling process for a single ion in a Penning ion trap. The situation is rather more complicated than in an r.f. trap, due to the presence of the magnetron drift. We show that under some circumstances the ion can get into an orbit which is different from the usual one in the trap, and that in order to apply laser cooling in this case one has to use a different procedure from the conventional one. We also present heating and cooling curves for the ion as a function of laser frequency and as a function of time.

Wayne M. Itano, Jonas Bergquist, J. J. Bollinger +1 more

Jürgen Eschner, Giovanna Morigi, Ferdinand Schmidt‐Kaler +1 more

Trapped and laser-cooled ions are increasingly used for a variety of modern high-precision experiments, for frequency standard applications, and for quantum information processing. Therefore laser cooling of trapped ions is reviewed, the current state of the art is reported, and several new cooling techniques are outlined. The principles of ion trapping and the basic concepts of laser cooling for trapped atoms are introduced. The underlying physical mechanisms are presented, and basic experiments are briefly sketched. Particular attention is paid to recent progress by elucidating several milestone experiments. In addition, a number of special cooling techniques pertaining to trapped ions are reviewed; open questions and future research lines are indicated.

C. Champenois