Coulomb crystallization of highly charged ions

Abstract

Control over the motional degrees of freedom of atoms, ions, and molecules in a field-free environment enables unrivalled measurement accuracies but has yet to be applied to highly charged ions (HCIs), which are of particular interest to future atomic clock designs and searches for physics beyond the Standard Model. Here, we report on the Coulomb crystallization of HCIs (specifically (40)Ar(13+)) produced in an electron beam ion trap and retrapped in a cryogenic linear radiofrequency trap by means of sympathetic motional cooling through Coulomb interaction with a directly laser-cooled ensemble of Be(+) ions. We also demonstrate cooling of a single Ar(13+) ion by a single Be(+) ion-the prerequisite for quantum logic spectroscopy with a potential 10(-19) accuracy level. Achieving a seven-orders-of-magnitude decrease in HCI temperature starting at megakelvin down to the millikelvin range removes the major obstacle for HCI investigation with high-precision laser spectroscopy.

Radiative recombination of twisted electrons with bare nuclei: Going beyond the Born approximation

“…Here we will focus only on the modification of the differential cross section. It can be shown that after the summation and averaging over the final and initial states projections, respectively, the differential cross section (38) can be written in the following form…”

“…Here we present the results only for the case of the bare argon (Z = 18) nucleus. Mesoscopic target consisting of such ions can be, in principle, created nowadays [38].…”

Experiments with Highly-Ionized Atoms in Unitary Penning Traps

“…Evaporative cooling of highly-charged ions stored in a Penning trap has been demonstrated recently [49]. Highly-charged Ar ions have been stopped and sympathetically cooled by an ensemble of laser-cooled Be + ions, forming a multi-species Coulomb crystal in a linear radio-frequency (RF) trap [50]. However, for studying transient phenomena, the application of a cooling technique may be limited by the cooling time constant, which can exceed the time scale of interest; an example is the study of the radiative decay of metastable states, as discussed in the next section.…”

\(\bar{\text{H}}^{+}\) Sympathetic Cooling Simulations with a Variable Time Step

“…Sympathetic cooling of externally loaded ions has been recently achieved for Ar 13+ [8,13] but the dynamics of the process have been little studied so far [14] especially for the case of very different mass-to-charge ratios as is the case in GBAR (9:1) [15]. Our goal is to numerically study this Dopplercooling step.…”

“…Sometimes the ions cannot be created in situ and therefore have to be externally loaded at relatively high energies of 0.1-10 eV. Such is the case of highly charged ions [8] and antimatter ions [9] that are (or will be) created in dedicated sources and are of interest for fundamental physics experiments. One example is the GBAR experiment which aims to coolH + ions made of an antiproton and two positrons at CERN and study their free fall to measure the gravity constantḡ on antimatter [10][11][12].…”