Anisotropic Polarizability of Ultracold Ground-state $^{23}$Na$^{87}$Rb Molecules

TL;DR

This study measures the anisotropic ac polarizabilities of ultracold $^{23}$Na$^{87}$Rb molecules in different rotational states, revealing how light polarization affects molecular coherence.

Contribution

It provides precise measurements of rotational state polarizabilities and demonstrates how to optimize light polarization to maximize rotational coherence time.

Findings

Polarizability of $J=0$ is isotropic.

Polarizability of $J=1$ is anisotropic and polarization-dependent.

Optimized polarization enhances coherence time.

Abstract

We report measurements of the ac polarizabilities of ultracold ground-state $^{23}\rm{Na}^{87}\rm{Rb}$ molecules. While the polarizability of the ground rotational state $J = 0$ is isotropic, that of the first excited rotational state $J = 1$ is anisotropic and depends strongly on the light polarization angle. We obtain both polarizabilities precisely by combining trap oscillation frequency measurement and high resolution rotational spectroscopy driven by microwave. 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.