Efficient conversion of closed-channel-dominated Feshbach molecules of 23Na40K to their absolute ground state

We demonstrate the transfer of (NaK)-Na-23-K-40 molecules from a closed-channel-dominated Feshbach-molecule state to the absolute ground state. The Feshbach molecules are initially created from a gas of sodium and potassium atoms via adiabatic ramping over a Feshbach resonance at 78.3 G. The molecules are then transferred to the absolute ground state using stimulated Raman adiabatic passage with an intermediate state in the spin-orbit-coupled complex vertical bar c(3)Sigma(+), upsilon = 35, J = 1 > - vertical bar B-1 Pi, upsilon = 12, J = 1). Our measurements show that the pump transition dipole moment linearly increases with the closed-channel fraction. Thus, the pump-beam intensity can be two orders of magnitude lower than is necessary with open-channel-dominated Feshbach molecules. We also demonstrate that the phase noise of the Raman lasers can be reduced by filter cavities, significantly improving the transfer efficiency.

Automated summary

This study demonstrates the transfer of (NaK)-Na-23-K-40 molecules from a closed-channel-dominated Feshbach-molecule state to the absolute ground state by using stimulated Raman adiabatic passage and reveals that the pump transition dipole moment linearly increases with the closed-channel fraction. It is also shown that the phase noise of the Raman lasers can be reduced by filter cavities, significantly improving the transfer efficiency.