EGAS41 - Swansea University

41 st EGAS CP 169 Gdańsk 2009
Dynamics of rf trapped Ca + ions
M. Marciante, C. Champenois, J. Pedregosa, A. Calisti, M. Knoop ∗
Universit de Provence-CNRS, Physique des Interactions Ioniques et Molculaires, Centre de St
Jrme, Case C21, Marseille, France
∗ Corresponding author: Martina.Knoop@univ-provence.fr,
Radiofrequency (rf) trapped ions are an ideal test bed for a wide range of applications from
frequency metrology to quantum computation. Our new experiment aims to trap a large
ion cloud to study its dynamics, in particular phase transitions to the crystallized state as
well as finite-size effects. The density of the charged ion cloud is limited by the Coulomb
repulsion and depends on the electrodynamic potential which is applied for confinement.
We intend to trap a cloud of 10 7 ions in a linear trap of 50 mm length, in order to
achieve densities which allow to study crystallization dynamics and ordered structures of
a large atomic ensemble. We will present the design of a double radiofrequency trap being
composed of a quadrupole and a multipole part which allows to shuttle the ions from a
parabolic potential well to a flatter potential and which will give insight on the influence
of the potential form on the phase transition process.
The set-up of the experiment is accompanied by molecular dynamics simulations for
the evaluation of the dynamics of ions in radiofrequency traps of different geometry, using
the pseudo-potential approximation or the exact time oscillating description. Doppler
laser cooling is taken into account by momentum kicks on absorption and emission of a
photon by an ion.
Figure 1: Isopotential lines of a quadrupole (left) and an octupole (right) trap.
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