Work

Improving the stimulated Raman adiabatic passage efficiency for ultracold 6Li40K ground state molecules

Year: 2025

Type: article

Abstract: Ultracold polar molecules represent a rapidly advancing platform at the forefront of quantum simulation, quantum computation, quantum chemistry, and precision measurement. We report an experimental investigation for improving the creation efficiency of ultracold 6Li40K ground state molecules using stimulated Raman adiabatic passage (STIRAP). We address laser amplitude/phase noise and polarization impurity to improve STIRAP efficiency. The phase noise of our two Raman lasers is suppressed effectively by extending the cavity length for the external-cavity diode lasers (ECDLs). Further, we find that even a weak polarization impurity significantly reduces the STIRAP efficiency on the single-photon resonance (Δ = 0) for 6Li40K, due to coupling to undesired molecular levels. However, STIRAP efficiencies over 90% can be achieved by increasing Δ/2π to 10 MHz, which is comparable to the excited-state scattering rate. Our work holds significance for achieving efficient STIRAP transfer in ultracold molecules with unresolved excited-state hyperfine splittings and large scattering rates.

Source: Communications Physics

DOI: 10.1038/s42005-025-02309-5