Improved isotope-shift-based bounds on bosons beyond the Standard Model through measurements of the $^2$D$_{3/2} - ^2$D$_{5/2}$ interval in Ca$^+$

Abstract

We perform high-resolution spectroscopy of the 3d 2 D 3/2 − 3d 2 D 5/2 interval in all stable even isotopes of A Ca + (A = 40, 42, 44, 46 and 48) with an accuracy of ∼ 20 Hz using direct frequencycomb Raman spectroscopy. Combining these data with isotope shift measurements of the 4s 2 S 1/2 ↔ 3d 2 D 5/2 transition, we carry out a King plot analysis with unprecedented sensitivity to coupling between electrons and neutrons by bosons beyond the Standard Model. Furthermore, we estimate the sensitivity to such bosons from equivalent spectroscopy in Ba + and Yb + . Finally, the data yield isotope shifts of the 4s 2 S 1/2 ↔ 3d 2 D 3/2 transition at 10 part-per-billion through combination with recent data of Knollmann et al. [1].

Perspectives on testing fundamental physics with highly charged ions in Penning traps

“…In order not to be limited by the masses of the involved isotopes, high-precision Penning-trap mass measurements on the isotopic chains of interest, e.g. Ca, Sr, and Yb [51,52], needs to be performed with relative mass uncertainties of δm/m = 1 • 10 −11 , as recently demonstrated by PENTATRAP [53].…”

Coherent excitation of the highly forbidden electric octupole transition in ${}^{172}$Yb$^+$

“…An additional Stark shift stems from blackbody radiation (BBR) [35]. At an effective temperature at the ion position of 297(3) K [36,37], the BBR shift is calculated to be -0.24 (11) Hz for the E2 and −0.07(3) Hz for the E3 transition, limited by the instability of the lab temperature. The involved differential polarizability for the E2 transition is computed to be −4.5(2.3) × 10 −40 Jm 2 V −2 using Refs.…”

“…These measurements are especially sensitive for the search of a possible neutron number dependent 5 th force, mediated by an unknown boson, coupling electrons with neutrons [6][7][8][9]. Very recent measurements of the E2 transitions in Ca + with accuracies on the order of 10 Hz [10,11] have not yet led to significant signatures. Here, the Yb + ion is more suitable due to its higher sensitivity of a factor of ten [8].…”

Testing gravity with cold atom interferometry: Results and prospects

“…The effect of the interactions would be detected as a deviation from the expected linearity in the so called King plots, that is, in the plot of the measured isotope shifts for one transitions vs the shift for the other. Recent results of experiments were reported in [302,303]. In [303], the isotope shifts for the 3d 2 D 3/2 -3d 2 D 5/2 fine structure transition was measured for the five stable zero-spin isotopes of Ca + and combined with measured isotope shifts for the 4s 2 S 1/2 -3d 2 D 5/2 transition.…”

“…Recent results of experiments were reported in [302,303]. In [303], the isotope shifts for the 3d 2 D 3/2 -3d 2 D 5/2 fine structure transition was measured for the five stable zero-spin isotopes of Ca + and combined with measured isotope shifts for the 4s 2 S 1/2 -3d 2 D 5/2 transition. No nonlinearity was found in the King plots within the experimental uncertainties.…”