Quantum state preparation and control of single molecular ions
Dietrich G. Leibfried
Preparing molecules at rest and in a highly pure electronic, rotational and vibrational quantum state is a long standing dream in chemistry and physics, so far only achieved for a select set of molecules in experimental setups dedicated to that species. Here, a quantum-limited combination of mass spectrometry and Raman-spectroscopy is proposed that should be applicable to a wide range of molecular ions. No excitation of electrons in the molecule followed by uncontrolled decay and branching into several lower energy states is required. Instead, the molecule is always confined to a small number of rotational states within the electronic and vibrational ground state manifold, while a co-trapped atomic ion provides efficient entropy removal and allows for extraction of information on the molecule. The outlined techniques might enable preparation, manipulation and measurement of pure quantum states of a large multitude of highly isolated and precisely prepared molecular ion species with the same instrument. Such a device could lead to unprecedented opportunities for precision molecular spectroscopy with applications including, but not limited to, determination of molecular properties for physics and chemistry to tests of fundamental laws of physics.