Observation of blue-shifted ultralong-range Cs$_{2}$ Rydberg molecules

TL;DR

This paper reports the experimental observation of blue-shifted ultralong-range Cs₂ Rydberg molecules formed near specific Rydberg states, revealing non-adiabatic couplings, large dipole moments, and agreement with theoretical predictions.

Contribution

First experimental observation of blue-shifted ultralong-range Cs₂ Rydberg molecules near $ns$ states with detailed analysis of their properties and formation mechanisms.

Findings

Observation of ultralong-range Cs₂ Rydberg molecules with large dipole moments.

Excellent agreement between experimental results and theoretical models.

Identification of non-adiabatic couplings leading to potential wells above $ns$ thresholds.

Abstract

We observe ultralong-range blue-shifted Cs$_{2}$ molecular states near $ns_{1/2}$ Rydberg states in an optical dipole trap, where $31\leq n\leq34$. The accidental near degeneracy of $(n-4)l$ and $ns$ Rydberg states for $l>2$ in Cs, due to the small fractional $ns$ quantum defect, leads to non-adiabatic coupling among these states, producing potential wells above the $ns$ thresholds. Two important consequences of admixing high angular momentum states with $ns$ states are the formation of large permanent dipole moments, $\sim 15-100\,$Debye, and accessibility of these states via two-photon association. The observed states are in excellent agreement with theory. Both projections of the total angular momentum on the internuclear axis are visible in the experiment.