Quadratic Zeeman and Electric Quadrupole Shifts in Highly Charged Ions

Abstract: Recent advances in high-precision spectroscopy of highly charged ions necessitate an understanding of energy shifts of ionic levels caused by external electric and magnetic fields. Beyond the well-known Stark and linear Zeeman shifts, trapped ions may also exhibit quadratic Zeeman and electric quadrupole shifts. In this contribution, we present a systematic approach for the theoretical analysis of these shifts for arbitrary many-electron ions. Based on the derived expressions and making use of the multiconfigurational Dirac-Fock approach, we performed calculations of quadratic Zeeman shift coefficients and quadrupole moments for various ionic states in Ca$^{14+}$, Ni$^{12+}$ and Xe$^{q+}$ ions. These ions attract particular interest for ongoing and future experiments in optical clocks and tests of fundamental physics.