Electron-Hole Transitions in Multiply Charged Ions for Precision Laser Spectroscopy and Searching for Variations inα

Abstract

We consider transitions of electron holes (vacancies in otherwise filled shells of atomic systems) in multiply charged ions that, due to level crossing of the holes, have frequencies within the range of optical atomic clocks. Strong E1 transitions provide options for laser cooling and trapping, while narrow transitions can be used for high-precision spectroscopy and tests of fundamental physics. We show that hole transitions can have extremely high sensitivity to α variation and propose candidate transitions that have much larger α sensitivities than any previously seen in atomic systems.

Hyperfine-induced electric dipole contributions to the electric octupole and magnetic quadrupole atomic clock transitions

“…Measuring the ratio of frequency of this transition to the frequency of the 4f 14 6s 2 S 1/2 − 4f 14 5d 2 D 3/2 transition in the same ion put the strongest limit on the temporal variation of the fine structure constant and (by including the Cs hyperfine transition) on the proton-to-electron mass ratio [8,9,[22][23][24]. The use of the electric octupole transition in Yb + for the search of LLI violation may lead to five orders of magnitude improvement over current best bounds on the LLI violation in the electron-photon sector [11].Many similar opportunities come with the use of optical transitions in highly-charged ions (HCI) [2][3][4][5]10]. For example, the spectrum of the Ir 17+ ion has been recently measured [25] with the prospect of using the 4f 13 5s 3 F o 4 − 4f 12 5s 2 3 H 6 transition for the time keeping and fundamental research.…”

“…Many similar opportunities come with the use of optical transitions in highly-charged ions (HCI) [2][3][4][5]10]. For example, the spectrum of the Ir 17+ ion has been recently measured [25] with the prospect of using the 4f 13 5s 3 F o 4 − 4f 12 5s 2 3 H 6 transition for the time keeping and fundamental research.…”

“…Electric octupole (E3) and magnetic quadrupole (M2) atomic optical transitions, which correspond to transitions between s and f electron orbitals, can be used as optical clocks of exceptionally high accuracy [1][2][3][4][5]. They also present unique opportunities for fundamental research by being sensitive to new physics beyond the Standard Model.…”

“…They also present unique opportunities for fundamental research by being sensitive to new physics beyond the Standard Model. The transitions are very sensitive to the temporal variation of the fine structure constant α (α = e 2 /hc) [2][3][4][5][6][7][8][9][10], to the local Lorentz invariance (LLI) violation [11], the effect of dark matter [12][13][14][15][16][17][18], etc. For example, the 4f 14 6s 2 S 1/2 − 4f 13 6s 2 2 F o 7/2 transition in Yb + offers opportunities for frequency measurements with fractional accuracy ∼ 10 −18 [1].…”

Optical clock sensitive to variations of the fine-structure constant based on theHo14+ion

“…A number of optical clock transitions sensitive to variation of α were found and examined in Refs. [10][11][12][13][14][15][16][17].…”