Dark resonances for ground state transfer of molecular quantum gases

TL;DR

This paper demonstrates the observation of two-photon dark resonances in ultracold Cs_2 molecules, paving the way for coherent transfer of molecular quantum gases to their rovibrational ground state using STIRAP.

Contribution

It reports the first observation of two-photon dark resonances in ultracold Cs_2 molecules and shows their potential for efficient ground state transfer via STIRAP.

Findings

Observation of two-photon dark resonances in Cs_2 molecules

Identification of a strong two-photon resonance suitable for STIRAP

Potential for coherent transfer of molecules to the rovibrational ground state

Abstract

One possible way to produce ultracold, high-phase-space-density quantum gases of molecules in the rovibronic ground state is given by molecule association from quantum-degenerate atomic gases on a Feshbach resonance and subsequent coherent optical multi-photon transfer into the rovibronic ground state. In ultracold samples of Cs_2 molecules, we observe two-photon dark resonances that connect the intermediate rovibrational level |v=73,J=2> with the rovibrational ground state |v=0,J=0> of the singlet $X^1\Sigma_g^+$ ground state potential. For precise dark resonance spectroscopy we exploit the fact that it is possible to efficiently populate the level |v=73,J=2> by two-photon transfer from the dissociation threshold with the stimulated Raman adiabatic passage (STIRAP) technique. We find that at least one of the two-photon resonances is sufficiently strong to allow future implementation of coherent STIRAP transfer of a molecular quantum gas to the rovibrational ground state |v=0,J=0>.