Precisely Spun Super Rotors

TL;DR

This paper presents a broadband optical method to create and maintain super rotor ensembles of SiO$^+$ molecules in high rotational states, enabling advanced spectroscopy and probing of molecular structure far from equilibrium.

Contribution

It introduces a novel broadband optical pumping technique to produce long-lived super rotors in high rotational states, expanding capabilities in molecular quantum control.

Findings

Super rotors pumped up to N=67 with narrow N spread.

Spectroscopy of the unobserved C$^2\Pi$ state.

Probing electronic structure at high rotational excitation.

Abstract

Improved optical control of molecular quantum states promises new applications including chemistry in the quantum regime, precision tests of fundamental physics, and quantum information processing. While much work has sought to prepare ground state molecules, excited states are also of interest. We demonstrate a broadband optical approach to pump trapped SiO$^+$ molecules into pure super rotor ensembles maintained for many minutes. Super rotor ensembles pumped up to rotational state $N=67$, corresponding to the peak of a 9400 K distribution, had a narrow $N$ spread comparable to that of a few-kelvin sample, and were used for spectroscopy of the previously unobserved C$^2\Pi$ state. Significant centrifugal distortion of super rotors pumped up to $N=230$ allowed probing electronic structure of SiO$^+$ stretched far from its equilibrium bond length.