  Quantum-logic techniques for state preparation, manipulation, and
non-destructive interrogation are increasingly being adopted for experiments on
single molecular ions confined in traps. The ability to control molecular ions
on the quantum level via a co-trapped atomic ion offers intriguing
possibilities for new experiments in the realms of precision spectroscopy,
quantum information processing, cold chemistry, and quantum technologies with
molecules. The present article gives an overview of the basic experimental
methods, recent developments and prospects in this field.
