Rb molecules*

Ultracold polar molecules with the strong, long-range, and anisotropic electric dipole-dipole interaction are attracting more and more researching interest, as a promising platform for applications in quantum simulation and quantum computation. For achieving various quantum phases, maintaining a long coherence time between the rotational levels for trapped molecules is often necessary. Here, we report measurements of the AC polarizabilities of ultracold ground-state ²³Na⁸⁷Rb molecules. By combining trap oscillation frequency measurement and high-resolution rotational spectroscopy driven by microwave, we obtain both the isotropic polarizability of the ground rotational state J= 0 and the anisotropic polarizability of the first excited rotational state J= 1. With the optimized light polarization angle and intensity combination, the nonuniformity of the differential AC Stark shift between the two rotational states is minimized and the rotational coherence time is observed to be the longest.