Molecular spectroscopy for ground-state transfer of ultracold RbCs molecules

TL;DR

This study uses high-resolution spectroscopy on ultracold RbCs molecules to identify a pathway for efficient transfer to their ground state, achieving highly precise measurements crucial for quantum gas applications.

Contribution

The paper reports the first precise measurement of the binding energy of the lowest rovibrational level of RbCs ground state molecules, enabling efficient two-photon Raman transfer.

Findings

Precise binding energy measurement of |v=0,J=0> state: 3811.5755(16) cm^{-1}.

Identification of rovibrational levels suitable for ground-state transfer.

Demonstration of potential for stimulated two-photon Raman transfer.

Abstract

We perform one- and two-photon high resolution spectroscopy on ultracold samples of RbCs Feshbach molecules with the aim to identify a suitable route for efficient ground-state transfer in the quantum-gas regime to produce quantum gases of dipolar RbCs ground-state molecules. One-photon loss spectroscopy allows us to probe deeply bound rovibrational levels of the mixed excited (A1{\Sigma}+ - b3{\Pi}0) 0+ molecular states. Two-photon dark state spectroscopy connects the initial Feshbach state to the rovibronic ground state. We determine the binding energy of the lowest rovibrational level |v"=0,J"=0> of the X1{\Sigma}+ ground state to be DX 0 = 3811.5755(16) 1/cm, a 300-fold improvement in accuracy with respect to previous data. We are now in the position to perform stimulated two-photon Raman transfer to the rovibronic ground state.