Eliana Ruth Wallach

Precision metrology, quantum information, and quantum-controlled chemistry studies all have many implementations in trapped ion systems that require a precise understanding of the motional dynamics of ions. Between the well-studied Coulomb-crystal and gaseous regimes lies the intermediate liquid-like regime whose properties and boundaries have largely eluded experimental investigation. Here, we track the entire liquid-to-gas transition process by leveraging direct velocity measurements using our newly developed ion-trap with integrated velocity map imaging. We demonstrate that the colder the ensemble, the more viscous the ion motion becomes until radial localization emerges, which marks the onset of the liquid regime at a temperature warmer than commonly assigned. At even hotter temperatures, we observe an abrupt change in the heating rate power-law, which indicates the maximum density threshold. The enhanced sensitivity of direct velocity measurements reveals the full transition process from a fluid with short-range order to a weakly-interacting gas.

Parity non-conservation (PNC) due to the weak interaction is predicted to give rise to enantiomer dependent vibrational constants in chiral molecules, but the phenomenon has so far eluded experimental observation. The enhanced sensitivity of molecules to physics beyond the Standard Model (BSM), has led to substantial advances in molecular precision spectroscopy, and these may be applied to PNC searches as well. Specifically, trapped molecular ion experiments leverage the universality of trapping charged particles to optimize the molecular ion species studied toward BSM searches, but in searches for PNC only a few chiral molecular ion candidates have been proposed so far. Importantly, viable candidates need to be internally cold and their internal state populations should be detectable with high quantum efficiency. To this end, we focus on molecular ions that can be created by near threshold resonant two-photon ionization and detected via state-selective photo-dissociation. Such candidates need to be stable in both charged and neutral chiral versions to be amenable to these methods. Here, we present a collection of suitable chiral molecular ion candidates we have found, including CHDBrI$^+$ and CHCaBrI$^+$, that fulfill these conditions according to our \textit{ab initio} calculations. We find that organo-metallic species have a low ionization energy as neutrals and relatively high dissociation thresholds. Finally, we compute the magnitude of the PNC values for vibrational transitions for some of these candidates. An experimental demonstration of state preparation and readout for these candidates will be an important milestone toward measuring PNC in chiral molecules for the first time.