Spectroscopy of Rydberg States in Erbium using Electromagnetically Induced Transparency

TL;DR

This study maps the Rydberg spectrum of erbium-166 using electromagnetically induced transparency, identifying around 550 states, and provides precise ionization thresholds and quantum defects, facilitating future quantum simulation applications.

Contribution

The paper presents the first comprehensive Rydberg spectrum of erbium-166 with detailed state assignments and improved ionization threshold measurements, advancing understanding of erbium's Rydberg states.

Findings

Identified approximately 550 Rydberg states in erbium-166.

Provided improved ionization threshold values with high precision.

Confirmed good agreement with multi-channel quantum defect theory.

Abstract

We present a study of the Rydberg spectrum in \ts{166}Er for series connected to the $4f^{12} (^3H_6) 6s$, $J_c=13/2 $ and $J_c=11/2 $ ionic core states using an all-optical detection based on electromagnetically induced transparency in an effusive atomic beam. Identifying approximately 550 individual states, we find good agreement with a multi-channel quantum defect theory (MQDT) which allows assignment of most states to $ns$ or $nd$ Rydberg series. We provide an improved accuracy for the lowest two ionization thresholds to $E_{\textrm{IP}, J_c = 13/2 } = 49260.750(1)\,$cm$^{-1}$ and $E_{\textrm{IP}, J_c = 11/2 } = 49701.184(1)\,$cm$^{-1}$ as well as the corresponding quantum defects for all observed series. We identify Rydberg states in five different isotopes, and states between the two lowest ionization thresholds. Our results open the way for future applications of Rydberg states for quantum simulation using erbium and exploiting its special open-shell structure.