EXAMPLES OF COUNTERINTUITIVE PHYSICS

This article describes some examples, involving atomic or molecular excitation by two nearly simultaneous coherent pulses of light, in which unexpected destructive interference has striking effects. In particular, population transfer between two atomic states can proceed to completion if the pulses occur in the reverse order to what naive intuition would suggest Some elementary theoretical descriptions of this phenomena are presented, and a few experimental applications of the concepts are discussed. The theory relies on such traditional concepts as quantum states and state vectors, as well as the less familiar constructs of trapped states, dressed states, dark states and adiabatic states, The experimental implementations include applications to state-selective studies of molecular reactions and to laser-induced cooling of atomic beams and deflection of atoms by multiple-photon momentum transfer.