Gabriel E. Patenotte

Polar molecules are a quantum resource with rich internal structure that can be coherently controlled. The structure, however, also makes the state preparation and measurement (SPAM) of molecules challenging. We advance the SPAM of individual molecules assembled from constituent atoms trapped in optical-tweezer arrays. Sites without $\mathrm{Na}\mathrm{Cs}$ molecules are eliminated using high-fidelity $\mathrm{Cs}$ atom detection, increasing the peak molecule filling fraction of the array threefold. We site-selectively initialize the array in a rotational qubit subspace that is insensitive to differential ac Stark shifts from the optical tweezer. Lastly, we detect multiple rotational states per experimental cycle by imaging atoms after sequential state-selective dissociations. These demonstrations extend the SPAM capabilities of molecules for quantum information, simulation, and metrology.

We report on photoassociation spectroscopy probing the $c^3{\mathrm{\Sigma }}_1^{+}$ potential of the bialkali NaCs molecule, identifying 11 vibrational lines between $v^{\prime }=0$ and $v^{\prime }=25$ of the excited $c^3{\mathrm{\Sigma }}_1^{+}$ potential and fitting their rotational and hyperfine structure. The observed lines are assigned by fitting to an effective Hamiltonian model of the excited-state structure with rotational and hyperfine constants as free parameters. We discuss unexpected broadening of select vibrational lines and its possible link to strong spin-orbit coupling of the $c^3{\mathrm{\Sigma }}_1^{+}$ potential with the nearby $b^3{\mathrm{\Pi }}_1$ and $B^1{\mathrm{\Pi }}_1$ manifolds. Finally, we report use of the $v^{\prime }=22$ line as an intermediate state for two-photon transfer of weakly bound Feshbach molecules to the rovibrational ground state of the $X^1{\mathrm{\Sigma }}^{+}$ manifold.