Demonstrate dipolar blockade and collisional stability in the j=3 storage state for molecule loading into optical tweezers

Demonstrate the dipolar blockade that prevents accumulation of more than one molecule in a single optical tweezer by shifting the j=1 ↔ j=2 microwave transition out of resonance in the presence of a stored j=3 molecule, and demonstrate the collisional stability of molecules prepared in the j=3 rotational storage state used in the proposed deterministic loading scheme for laser-cooled molecules.

Background

The paper proposes a scheme to achieve near-deterministic loading of optical tweezers with single laser-cooled molecules. The approach repeatedly loads j=1 molecules under collisional blockade, then transfers loaded molecules into a j=3 storage state via two microwave π pulses. Molecules in the storage state are designed to experience suppressed collisional loss due to repulsive rotational dispersion interactions and to induce a dipolar blockade that prevents further molecules from being transferred into the same tweezer.

The authors note that the enabling ingredients—laser cooling into tweezers, optical pumping or coherent population trapping to prepare internal states, and microwave π pulses—have all been experimentally realized. However, two key components specific to their scheme remain to be experimentally demonstrated: (i) the dipolar blockade effect in tweezers that distinguishes loaded from empty sites during subsequent cycles, and (ii) the collisional stability (suppressed loss) of molecules in the j=3 storage state under the conditions relevant to the loading cycles.