New Paths to Molecular Ion Quantum Logic

Molecular ion quantum systems may offer advantages over current platforms for certain tasks in quantum sensing, communication, and computation. Before these advantages can be realized, control of molecular ion qubits, e.g. quantum state preparation/measurement and entangling operations, must be improved to levels similar to those in atomic systems. Recent work has deciphered several long-standing riddles for one of these important steps: preparing molecular ions in a single internal quantum state via sympathetic cooling with laser-cooled gases. We will review these developments, which involve both ion-ion and ion-neutral collision physics. We will also discuss several new ideas for quantum logic using both dipolar and dipole-phonon interactions between these cooled molecular ions, which hold promise for rapidly advancing the field.