Ultracold Dipolar Gas of Fermionic Na23K40 Molecules in Their Absolute Ground State

Abstract

We report on the creation of an ultracold dipolar gas of fermionic Na23K40 molecules in their absolute rovibrational and hyperfine ground state. Starting from weakly bound Feshbach molecules, we demonstrate hyperfine resolved two-photon transfer into the singlet X1Σ+|v=0,J=0〉 ground state, coherently bridging a binding energy difference of 0.65 eV via stimulated rapid adiabatic passage. The spin-polarized, nearly quantum degenerate molecular gas displays a lifetime longer than 2.5 s, highlighting NaK's stability against two-body chemical reactions. A homogeneous electric field is applied to induce a dipole moment of up to 0.8 D. With these advances, the exploration of many-body physics with strongly dipolar Fermi gases of Na23K40 molecules is within experimental reach.