Sideband cooling of the radial modes of motion of a single ion in a Penning trap

Abstract

Doppler and sideband cooling are long standing techniques that have been used together to prepare trapped atomic ions in their ground state of motion. In this paper we study how these techniques can be extended to cool both radial modes of motion of a single ion in a Penning trap. We numerically explore the prerequisite experimental parameters for efficient Doppler cooling in the presence of an additional oscillating electric field to resonantly couple the radial modes. The simulations are supported by experimental data for a single 40 Ca + ion Doppler cooled to ∼100 phonons in both modes at a magnetron frequency of 52 kHz and a modified cyclotron frequency of 677 kHz. For these frequencies, we then show that mean phonon numbers of 0.35(5) for the modified cyclotron and 1.7(2) for the magnetron motions are achieved after 68 ms of sideband cooling.

Sympathetic cooling schemes for separately trapped ions coupled via image currents

“…For example, high-precision mass measurements of stable ions [54] or radionuclides with moderate lifetimes at online facilities [55,56], studies with molecular ions in radiofrequency traps [57] as well as trapped-ion quantum computing [58] could benefit from the techniques presented in this paper. Moreover, sub-Doppler cooling techniques such as sideband cooling [59,60] may be employed in the future to reach even lower temperatures.…”

Broadening of the drumhead mode spectrum due to in-plane thermal fluctuations of two-dimensional trapped ion crystals in a Penning trap

“…For single ions in Penning traps, improved cooling of the E × B motion has been proposed and demonstrated by applying a resonant drive that couples this mode to either the cyclotron mode or the out-of-plane mode, both of which are efficiently Doppler cooled. Recently, such 'axialization' techniques have been used to cool the E × B motion of a single ion down to the regime where sideband cooling can subsequently be used to further cool this mode to its ground state [12]. 1 Axialization has also recently been theoretically demonstrated to improve the cooling of E × B modes in small ion crystals stored in a Penning trap array [13].…”

“…Such systems have enabled the study of iconic and important spin and spin-boson models [1][2][3], of the growth of entanglement in large interacting systems [4,5], and of metrologically relevant protocols aimed at spin squeezing [6,7] and motion sensing [8,9]. A number of efforts are currently underway to expand the toolbox for quantum information processing with Penning traps, including the development of miniaturized permanent-magnet systems that offer portability [10] and traps with improved optical access [11], the incorporation of sideband cooling [12], and proposals for quantum computing and simulation in arrays of Penning traps [13].…”

Formation of Two-Ion Crystals by Injection from a Paul-Trap Source into a High-Magnetic-Field Penning Trap

“…[20,21]). This is not the case in laser cooling Penning-trap experiments (and in general in similar experiments with other kinds of ion traps) devoted to quantum sensing or quantum information processing [7,22,23]. In those experiments, the ion species to be laser-cooled are generally produced inside the Penning trap either by laser-desorption on a metallic sample located close to the trap electrodes (see e.g.…”