Ion transport in macroscopic RF linear traps

Abstract

Efficient transport of cold atoms or ions is a subject of increasing concern in many experimental applications reaching from quantum information processing to frequency metrology. For the scalable quantum computer architectures based on the shuttling of individual ions, different transport schemes have been developed, which allow to move single atoms minimizing their energy gain. In this article we discuss the experimental implementation of the transport of a three-dimensional ion cloud in a macroscopic linear radiofrequency (RF) trap. The present work is based on numerical simulations done by molecular dynamics taking into account a realistic experimental environment.The deformation of the trapping potential and the spatial extension of the cloud during transport appears to be the major source of the ion energy gain. The efficiency of transport in terms of transfer probability and ion number is also discussed.

Correcting symmetry imperfections in linear multipole traps

“…Molecular Dynamics (MD) simulations provide a virtual implementation of such a compensation for a particular experimental set-up, and allow to probe the influence of the corrected potential on the trapped ions. To this purpose, the code developed in [10,25], has been modified to use the CPO generated matrices containing the electric fields, E x , E y and a 5 th order interpolation is used to find the electric field at the ion position. The simulation parameters are : 128 Ca + -ions, a nominal value of RF (before corrections) of V RF = 300 V, Ω/2π = 3.5 MHz, ω z /2π = 100 kHz.…”

“…The MD simulations uses an initial velocity re-scaling algorithm that cools down the ions to a temperature of 10 mK [25]. While such technique is not physically correct, allows to speed up the simulation and provides initial conditions for the last part of the simulation, when the code switches to a laser cooling algorithm that uses a two-level models for the laser-interaction through absorption and emission of photons [24] The final ion temperatures, calculated as the averaged temperature over the last 3000 RF periods (≈ 0.9 ms), are T = 9.6 ± 0.7 mK and T = 14.2 ± 1.4 mK for the compensated and uncompensated case respectively.…”

Fast and efficient transport of large ion clouds

“…In these works, the authors characterize and compare different transport protocols with respect to the heating they induce on the ion motion. To guide us with our experiments, we have extrapolated these analysis for an ion cloud by using molecular dynamics (MD) simulations in [22]. We use the notations of previous work and we call φ i (x, y, z) the electric potential created by the DC-electrode i when 1V is applied to it.…”

“…Guided by numerical results detailed in [22], we used for the experiments presented here the time profile described by…”

“…In a perfectly symmetric device V 3 (t) = V 1 (t) would solve the problem but any asymmetry in the electrode environment breaks this equality. The reader is referred to [22] for details about how to avoid discontinuities in numerical simulations.…”