Observation of spin-orbit-dependent electron scattering using long-range Rydberg molecules

Markus Deiß,Frederic Hummel,Johannes Hecker Denschlag,Florian Meinert,Christian Fey,Joschka Wolf,Limei Wang,Shinsuke Haze,Peter Schmelcher

doi:10.1103/physrevresearch.2.013047

Abstract

We present experimental evidence for spin-orbit interaction of an electron as it scatters from a neutral atom. The scattering process takes place within a Rb$_2$ ultralong-range Rydberg molecule, consisting of a Rydberg atomic core, a Rydberg electron, and a ground state atom. The spin-orbit interaction leads to characteristic level splittings of vibrational molecular lines which we directly observe via photoassociation spectroscopy. We benefit from the fact that molecular states dominated by resonant $p$-wave interaction are particularly sensitive to the spin-orbit interaction. Our work paves the way for studying novel spin dynamics in ultralong-range Rydberg molecules. Furthermore, it shows that the molecular setup can serve as a microlaboratory to perform precise scattering experiments in the low-energy regime of a few meV.

Highlights

Since their prediction almost 20 years ago [1] and boosted by their first observation [2], ultralong-range Rydberg molecules have become a research area of major interest
We present experimental evidence for spin-orbit interaction of an electron as it scatters from a neutral atom
The spin-orbit interaction leads to characteristic level splittings of vibrational molecular lines which we directly observe via photoassociation spectroscopy

Summary

Introduction

Since their prediction almost 20 years ago [1] and boosted by their first observation [2], ultralong-range Rydberg molecules have become a research area of major interest (for reviews, see, e.g., [3,4,5]). One fundamental unresolved question concerns the coupling between the total electronic spin S and the relative orbital angular momentum Lp of the Rydberg electron with respect to the ground state perturber atom. The role of this Lp · S type spin-orbit interaction for the molecular system was predicted almost 20 years ago [6] and has remained a topic of active research until now [7,8]. It has escaped discovery a variety of spectroscopic studies with impressive resolution were carried out, investigating Rydberg molecules for various atomic species (Rb, Cs, Sr) and different Rydberg orbitals (S, P, or D) [2,10,11,12,13,14,15,16,17,18,19,20,21,22,23]

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