Efficient Creation of Ultracold Ground State $^{6}\textrm{Li}^{40}\textrm{K}$ Polar Molecules

TL;DR

This paper demonstrates an efficient method to produce ultracold $^{6}$Li$^{40}$K polar molecules in their ground state with high transfer efficiency, enabling future studies of quantum many-body physics with these molecules.

Contribution

The work introduces a highly efficient STIRAP-based technique for creating ultracold ground state LiK molecules with a 96% transfer efficiency using narrow-linewidth lasers.

Findings

Achieved 96% transfer efficiency to ground state.

Measured a 5 ms lifetime of molecules in an optical trap.

Confirmed large dipole moment via Stark spectroscopy.

Abstract

We report the creation of ultracold ground state $^{6}\textrm{Li}^{40}\textrm{K}$ polar molecules with high efficiency. Starting from weakly-bound molecules state, stimulated Raman adiabatic passage (STIRAP) is adopted to coherently transfer the molecules to their singlet ro-vibrational ground state $|\textrm{X}^{1}\Sigma^{+},v=0,J=0>$. By employing a singlet STIRAP pathway and low-phase-noise narrow-linewidth lasers, we observed a one-way transfer efficiency of 96(4)\,\%. Held in an optical dipole trap, the lifetime of the ground-state molecules is measured to be 5.0(3)\,ms. The large permanent dipole moment of LiK is confirmed by applying a DC electric field on the molecules and performing Stark shift spectroscopy of the ground state. With recent advances in the quantum control of collisions, our work paves the way for exploring quantum many-body physics with strongly-interacting $^{6}\textrm{Li}^{40}\textrm{K}$ molecules.