Quantum interference in laser spectroscopy of highly charged lithiumlike ions

TL;DR

This paper studies how quantum interference affects the measured transition frequencies in laser spectroscopy of highly charged lithiumlike ions, showing shifts up to 11% of the linewidth and analyzing relativistic effects.

Contribution

It provides a relativistic, full-multipole framework to quantify quantum interference shifts in highly charged ions, highlighting the minor role of higher multipoles and relativity.

Findings

Quantum interference can cause shifts up to 11% of the linewidth.

Relativity decreases the cross section by 35%.

Higher multipoles have negligible impact on shifts.

Abstract

We investigate the quantum interference induced shifts between energetically close states in highly charged ions, with the energy structure being observed by laser spectroscopy. In this work, we focus on hyperfine states of lithiumlike heavy-$Z$ isotopes and quantify how much quantum interference changes the observed transition frequencies. The process of photon excitation and subsequent photon decay for the transition $2s\rightarrow2p\rightarrow2s$ is implemented with fully relativistic and full-multipole frameworks, which are relevant for such relativistic atomic systems. We consider the isotopes $^{207}$Pb$^{79+}$ and $^{209}$Bi$^{80+}$ due to experimental interest, as well as other examples of isotopes with lower $Z$, namely $^{141}$Pr$^{56+}$ and $^{165}$Ho$^{64+}$. We conclude that quantum interference can induce shifts up to 11% of the linewidth in the measurable resonances of the considered isotopes, if interference between resonances is neglected. The inclusion of relativity decreases the cross section by 35%, mainly due to the complete retardation form of the electric dipole multipole. However, the contribution of the next higher multipoles (e.g. magnetic quadrupole) to the cross section is negligible. This makes the contribution of relativity and higher-order multipoles to the quantum interference induced shifts a minor effect, even for heavy-$Z$ elements.