Multichannel Quantum Defect Theory for Rydberg Molecular State

P. Zoller

David Grimes, Robert W. Field, Stephen L. Coy +1 more

The usual simplified view of Rydberg states of molecules as consisting of a single Rydberg electron loosely bound to a molecular ion core in a well-defined rotation-vibration state suggests an attractive possibility for state-selective production of molecular ions. A Rydberg electron excited above the energy of the ground state of the ion core will spontaneously autoionize, leaving behind a molecular ion. The autoionizing states are of strongly mixed character due to the ubiquitous nonadiabatic interactions between Rydberg series associated with different states of the ion core. Using our complete Multichannel Quantum Defect Theory (MQDT) fit model for CaF, we have predicted the locations and strengths of special autoionizing resonances that decay into a single rotation-vibration state of a molecular ion. Few molecules are as well characterized as CaF, nor as elegantly simple. We additionally describe the use of core nonpenetrating states as a general method to produce an ensemble of molecular ions in a single, selectable quantum state.

J. B. M. Warntjes

Ch. Jungen

Rin Kuroda, Vernon M. Hughes, Martin Poitrinal +2 more

The complex Rydberg structure of ytterbium atoms is shaped by multiple low-lying ion-core-excited states and strong channel interactions, which presents both opportunities and challenges for quantum information processing and precision metrology. In this work, we extend high-resolution microwave spectroscopy and multichannel quantum defect theory (MQDT) modeling of singly excited $6sn\ensuremath{\ell}$ Rydberg states in $^{174}\mathrm{Yb}$ and $^{171}\mathrm{Yb}$ to include the $\ensuremath{\ell}=3$ ($f$) and $\ensuremath{\ell}=4$ ($g$) series. Our measurements reveal $p\text{\ensuremath{-}}f$ mixing in odd-parity Rydberg states of $^{171}\mathrm{Yb}$, which we incorporate by combined MQDT models for $6snp$ and $6snf$ series. Additionally, we observe that for $\ensuremath{\ell}=4$ the spin-orbit interaction dominates over the exchange interaction, such that the $6sng$ states are more accurately described in a $jj$-coupled basis. We validate our models by comparing the predicted Land\'e $g$ factors and static dipole polarizabilities with experimental measurements, finding excellent agreement. These results provide important input for designing high-fidelity entangling gates with ytterbium atoms.

Christophe L. Vaillant, M. P. A. Jones, R. M. Potvliege

Abstract Newly calculated multichannel quantum defect theory parameters and channel fractions are presented for the singlet and triplet S, P and D series and singlet F series of strontium. These results correct those reported in Vaillant et al (2014 J. Phys. B: At. Mol. Opt. Phys. 47 155001).