The structure of planar Coulomb crystals in RF traps

Abstract

We investigate the structure of one-component and multicomponent planar Coulomb crystals in RF traps. Due to the RF confinement particular features emerge, especially in the case of multicomponent crystals. After briefly discussing one-component planar crystals, we consider the case of multicomponent crystals and, in particular, planar bicrystals. We show that in the multicomponent case, the spatial separation among components depends on the strength of axial confinement which also imposes a limit on the number of ions that can exist in the innermost shell. These theoretical results are confirmed by molecular dynamics simulations. Finally, we discuss some experimental issues.

Characterization of ion Coulomb crystals in a linear Paul trap

“…To our knowledge, there is only one experimental demonstration of planar Coulomb crystals in linear Paul traps [36], although such a system has been given much attention in the field of quantum calculations [2,26,27]. In the previous experiment [36], small planar crystals of up to 19 ions have been produced and were observed as images by a CCD camera.…”

“…During the past few decades, many simulation studies for ion Coulomb crystals in ion traps were performed by the molecular dynamics (MD) approach in order to study the properties and the structures of the Coulomb crystals [21][22][23][24][25][26][27]. For an ionic system in a linear Paul trap, the phase transition as a function of the anisotropy between axial and radial trapping potentials was studied in detail [21].…”

“…Recently, MD simulations in a linear multipole trap as well as a linear Paul trap were extensively performed in order to search for the experimental conditions to produce planar or ring-type Coulomb crystals, which might be applicable to quantum-information processing, quantum simulations, and quantum calculations [25][26][27]. Apart from the studies of such special forms of Coulomb crystals, some simulations were carried out to extract the properties, such as ion temperatures and the number of ions, from experimentally produced Coulomb crystals in a linear Paul trap [23,24].…”

“…As a demonstration of our method, we simulated the observed Coulomb crystals during the production processes of planar Coulomb crystals in a linear Paul trap, since there is much interest in these applications in the community of the fields of scalable quantum-information processing and quantum computation using ion Coulomb crystals in ion traps [2,26,27,30]. In this paper, the experimental result of the systematic transformation of a Coulomb crystal's shape with a definite number of ions is presented, and the images are compared to our simulation results.…”

Spatially-resolved potential measurement with ion crystals

“…By changing the ratio of axial to radial frequencies, or by increasing the number of ions in the trap, it is simple to create and image two-dimensional crystals of ions [23,24]. The generalisation of the Coulomb-force calculation (see Eq.…”