Dressed-State Spectroscopy and Magic Trapping of Microwave-Shielded NaCs Molecules

TL;DR

This study investigates the optical polarizability and dressed-state spectroscopy of microwave-shielded NaCs molecules, demonstrating a magic rotational transition that is insensitive to laser fluctuations, with implications for cooling and quantum simulation.

Contribution

We experimentally characterize the polarizability of dressed NaCs molecules and realize a magic rotational transition, advancing control over molecular quantum states.

Findings

Optical polarizability depends on microwave dressing parameters.

A magic rotational transition with minimal laser sensitivity was engineered.

Results are relevant for molecular cooling and many-body quantum systems.

Abstract

We report on the optical polarizability of microwave-shielded ultracold NaCs molecules in an optical dipole trap. While dressing a pair of rotational states with a microwave field, we observe a marked dependence of the optical polarizability on the intensity and detuning of the dressing field. To precisely characterize differential energy shifts between dressed rotational states, we establish dressed-state spectroscopy. For strong dressing fields, we find that a magic rotational transition can be engineered and demonstrate its insensitivity to laser intensity fluctuations. The results of this work have direct relevance for evaporative cooling and the recent demonstration of molecular Bose-Einstein condensates [Bigagli, et al., Nature (2024)] and may open a door to precision microwave spectroscopy in interacting many-body systems of microwave-shielded molecules.