Synthetic dimension-induced conical intersections in Rydberg molecules

TL;DR

This paper demonstrates the existence of conical intersections in Rydberg molecules using a synthetic dimension approach, revealing their impact on ultracold collision rates and atom transparency.

Contribution

It introduces a novel method to observe conical intersections in Rydberg molecules via synthetic dimensions, bypassing the von Neumann-Wigner theorem.

Findings

Conical intersections occur when the Rydberg atom's quantum defect matches a specific scattering phase shift.

Near these intersections, ultracold collision rates are significantly suppressed.

Rydberg atoms become nearly transparent to ground-state atoms at conical intersections.

Abstract

We observe a series of conical intersections in the potential energy curves governing both the collision between a Rydberg atom and a ground-state atom and the structure of Rydberg molecules. By employing the electronic energy of the Rydberg atom as a synthetic dimension we circumvent the von Neumann-Wigner theorem. These conical intersections can occur when the Rydberg atom's quantum defect is similar in size to the electron--ground-state atom scattering phase shift divided by $\pi$, a condition satisfied in several commonly studied atomic species. The conical intersections have an observable consequence in the rate of ultracold $l$-changing collisions of the type Rb$(nf)$+Rb$(5s)\to$ Rb$(nl>3)$+Rb$(5s)$. In the vicinity of a conical intersection, this rate is strongly suppressed, and the Rydberg atom becomes nearly transparent to the ground-state atom.