Quantum control of motional states of neutral atoms: Exploiting the external degrees of freedom

As research in quantum optics has advanced, so too has our ability to precisely tailor the quantum state of a system. Indeed, techniques for quantum state preparation have become sufficiently advanced that an entire subfield has appeared which has been given the name "quantum control" Parallel to these advances have been other striking developments in quantum optics, in particular, laser cooling and trapping of neutral atoms. In this paper we describe some of the recent advancements in laser cooling, particularly in our laboratories, and point out that laser cooling and trapping is also realizing an important form of quantum control. In laser cooling, instead of exercising control over the internal quantum state of an atom or molecule or a laser field, we are instead controlling a complementary set of degrees of freedom: those of the external coordinates of the atom.