Transition strength measurements to guide magic wavelength selection in optically trapped molecules

TL;DR

This paper combines experimental measurements and ab initio calculations to identify vibrational states in Sr2 molecules, enabling the selection of magic wavelengths for optical trapping that achieve long vibrational coherence times of nearly 100 ms.

Contribution

It introduces a method to determine vibrational quantum numbers and refine potential energy curves, guiding the choice of magic wavelengths for improved molecular coherence.

Findings

Vibronic line strengths help identify vibrational quantum numbers.

Refined potential energy curves inform magic wavelength selection.

Achieved Rabi oscillations lasting nearly 100 ms.

Abstract

Optical trapping of molecules with long coherence times is crucial for many protocols in quantum information and metrology. However, the factors that limit the lifetimes of the trapped molecules remain elusive and require improved understanding of the underlying molecular structure. Here we show that measurements of vibronic line strengths in weakly and deeply bound $^{88}$Sr$_2$ molecules, combined with \textit{ab initio} calculations, allow for unambiguous identification of vibrational quantum numbers. This, in turn, enables the construction of refined excited potential energy curves that inform the selection of magic wavelengths which facilitate long vibrational coherence. We demonstrate Rabi oscillations between far-separated vibrational states that persist for nearly 100 ms.