http://nuclearmasses.org/resources_folder/Blaum_06.pdf

High-accuracy mass spectrometry with stored ions

Improved control of the motional and internal quantum states of ultracold neutral atoms and ions has opened intriguing possibilities for quantum simulation and quantum computation. Many-body effects have been explored with hundreds of thousands of quantum-degenerate neutral atoms, and coherent light-matter interfaces have been built. Systems of single or a few trapped ions have been used to demonstrate universal quantum computing algorithms and to search for variations of fundamental constants in precision atomic clocks. Until now, atomic quantum gases and single trapped ions have been treated separately in experiments. Here we investigate whether they can be advantageously combined into one hybrid system, by exploring the immersion of a single trapped ion into a Bose-Einstein condensate of neutral atoms. We demonstrate independent control over the two components of the hybrid system, study the fundamental interaction processes and observe sympathetic cooling of the single ion by the condensate. Our experiment calls for further research into the possibility of using this technique for the continuous cooling of quantum computers. We also anticipate that it will lead to explorations of entanglement in hybrid quantum systems and to fundamental studies of the decoherence of a single, locally controlled impurity particle coupled to a quantum environment.

/pdf/a-trapped-single-ion-inside-a-bose-einstein-condensate-nw81yr9zo8.pdf

A trapped single ion inside a Bose-Einstein condensate.

Electronic states of highly charged ions show magnified fine-structure, Lamb shift, and hyperfine effects making them sensitive probes of bound-state quantum electrodynamics and nuclear physics. Being also impervious to external perturbations renders them ideal candidates for precision spectroscopy and accurate clocks that could test physics beyond the standard model. This review discusses how a variety of ion species and transitions may optimally be used to target such new applications, and presents routes to handle them in the laboratory.

Highly charged ions: Optical clocks and applications in fundamental physics

This paper reviews some of the fundamental properties of highly charged ions, the methods of producing them (with particular emphasis on table-top devices), and their use as a tool for both basic science and applied technology. Topics discussed include: charge dependence and scaling laws along isoelectronic or isonuclear sequences (for wavefunction size or Bohr radius, ionization energy, dipole transition energy, relativistic fine structure, hyperfine structure, Zeeman effect, Stark effect, line intensities, linewidths, strength of parity violation, etc), changes in angular momentum coupling schemes, selection rules, interactions with surfaces, electron-impact ionization, the electron beam ion trap (EBIT), ion accelerators, atomic reference data, cosmic chronometers, laboratory x-ray astrophysics, vacuum polarization, solar flares, ion implantation, ion lithography, ion microprobes (SIMS and x-ray microscope), nuclear fusion diagnostics, nanotechnology, quantum computing, cancer therapy and biotechnology.

https://iopscience.iop.org/article/10.1088/0953-4075/34/19/201/pdf

Highly charged ions

Detailed measurements, line identifications, and modeling calculations of the Fe XVII L-shell emission spectrum between 9.8 and 17.5 A are presented. The measurements were carried out on an electron beam ion trap under precisely controlled conditions where electron-impact excitation followed by radiative cascades is the dominant line formation process. In addition to the strong transitions emanating from the n = 3 shell, we identify and accurately determine wavelengths for transitions from higher shells up to n = 11, including two electric quadrupole transitions that have not been previously identified. Various theoretical values, including new distorted wave calculations, are compared to our measurements, which establish definitive values for testing spectral modeling predictions. We find a value of 3.04 ± 0.12 for the ratio of the intensity of the 2p-3d1P1 resonance and of the 2p-3d3D1 intercombination line situated at 15.01 and 15.26 A, respectively. This value is higher than the values observed in solar spectra, which supports claims that the solar value is affected by resonant scattering. However, because our value is significantly lower than calculated values, the amount of scattering has probably been overestimated in past analyses. Comparisons of the measured intensity ratios of the transitions originating in levels of higher principal quantum number n with present distorted wave calculations show good agreement up to n = 6. The combined flux of all 2p-nd transitions with n ≥ 5 and all 2s-np transitions with n = 4 and 5 relative to the flux of the 15.01 A resonance line has been measured to be 0.13+ 0.04−0.03 .

https://iopscience.iop.org/article/10.1086/305941/pdf

Laboratory Measurements and Modeling of the Fe XVII X-Ray Spectrum

An electron beam ion trap has been built for the production of very-highly-charged ions and the study of their collisions with electrons. A high density electron beam is used to trap, ionize and excite the ions for spectroscopic measurements. X-ray spectra from neon-like Ba46+ are reported and a theory of "evaporative" cooling is developed to explain why these ions are retained in the trap for surprisingly long times.

https://iopscience.iop.org/article/10.1088/0031-8949/1988/T22/024/pdf

The Electron Beam Ion Trap: A New Instrument for Atomic Physics Measurements

The self-energy contribution to the transition (2{ital s}{sub 1/2}2{ital p}{sup 6}3{ital p}{sub 3/2}){sub {ital J}=1}{r arrow}2{ital s}{sup 2}2{ital p}{sup 6} in neonlike Yb{sup 60+} has been measured in an electron-beam ion trap to be 18.4{plus minus}0.8 eV. This value is 10% larger than the value obtained from multiconfiguration Dirac-Fock calculations in the commonly used effective-charge approach. The measurement supports earlier suggestions that the effective-charge approach may overcorrect the screening effect on the self-energy corrections for transitions in neonlike ions.

Measurement of the self-energy contribution to the 2s-3p resonance transition in neonlike ytterbium

The {ital LMM} dielectronic recombination resonances of a neonlike ion (Au{sup 69+}) have been observed. The ions were produced and held in an electron-beam ion trap. The intensity of the {ital n}=3{r arrow}2 x rays resulting from dielectronic recombination was measured as a function of electron-beam energy with sufficient resolution to distinguish the structure of the {ital LMM} resonances. The measured resonance strengths for {ital LMM} resonances with a 2{ital p}{sub 3/2}{sup {minus}1} core are in good agreement with theoretical predictions, but there is some disagreement for the 2{ital p}{sub 1/2}{sup {minus}1} and 2{ital s}{sub 1/2}{sup {minus}1} core configurations.

Measurement of the LMM dielectronic recombination resonances of neonlike gold.

We present measurements of the relative electron-impact-excitation cross sections for the 1{ital s}{sup 2} {sup 1}S{sub 0}--1{ital s}2{ital p} {sup 1}P{sub 1}, 1{ital s}{sup 2} {sup 1}S{sub 0}--1{ital s}2{ital p} {sup 3}P{sub 2}, 1{ital s}{sup 2} {sup 1}S{sub 0}--1{ital s}2{ital p} {sup 3}P{sub 1}, and 1{ital s}{sup 2} {sup 1}S{sub 0}--1{ital s}2{ital s} {sup 3}S{sub 1} transitions for the He-like ion, Fe{sup 24+}. The measurements were made at two electron energies: 6.86 and 9.94 keV. The cross-section measurements are compared with theoretical calculations.

Measurement of relative electron-impact excitation cross sections for Fe24+

Both the total number and trapping lifetime of near‐neon‐like gold ions held in an electron beam ion trap have been greatly increased by a process of ‘evaporative cooling.’ A continuous flow of low‐charge‐state ions into the trap cools the high‐charge‐state ions in the trap. Preliminary experimental results using titanium ions as a coolant are presented.

M. A. Levine

Papers

The Electron Beam Ion Trap: A New Instrument for Atomic Physics Measurements

Measurement of the self-energy contribution to the 2s-3p resonance transition in neonlike ytterbium

Measurement of the LMM dielectronic recombination resonances of neonlike gold.

Measurement of relative electron-impact excitation cross sections for Fe24+

Evaporative cooling of highly charged ions in EBIT: An experimental realization