Determination of Quantum Defects and Core Polarizability of Atomic Cesium via Terahertz and Radio-Frequency Spectroscopy in Thermal Vapor

TL;DR

This study measures quantum defects and core polarizabilities of cesium Rydberg states using terahertz and radio-frequency spectroscopy, achieving high-precision energy level estimations.

Contribution

It provides new experimental data and analysis methods for quantum defects and polarizabilities in cesium, improving the accuracy of Rydberg state energy predictions.

Findings

Quantum defects for multiple cesium Rydberg states determined.

Core polarizabilities of cesium measured with high precision.

Estimated Rydberg energy levels with a few MHz accuracy.

Abstract

We present new measurements of quantum defects and core polarizabilities in cesium ($^{133}$Cs), based on transition frequency measurements between Rydberg states ($14 \leq n \leq 38$) obtained through terahertz (THz) and radio-frequency spectroscopy in a thermal atomic vapor. %By detuning resonant fields coupling neighbouring Rydberg states, we observe a detuning-dependent asymmetry in the line shape which can be used to extract the frequency of the transition. We perform a global fitting of our measurements to extract quantum defects of the $s_{1/2}$, $p_{1/2}$, $p_{3/2}$, $d_{3/2}$, $d_{5/2}$, $f_{5/2}$, $f_{7/2}$, $g_{7/2}$ and $g_{9/2}$ electronic states. Transitions between high angular momentum states ($4 \leq \ell \leq 8$) were measured to extract the Cs$^{+}$ dipole and quadrupole polarizabilities. We find $\alpha_{d} = 15.729(18)$ $a_{0}^{3}$ and $\alpha_{q} = 76.3(1.9)$ $a_{0}^{5}$ respectively. Using these results, and accounting for the covariances between parameters in the global fit, the energies for $n\ell_{j}$ Rydberg states can be estimated to a precision of a few MHz or less.