Sensing the internal dynamics of delocalized molecules

Delocalization of massive objects is a fundamentally non-classical and non-intuitive phenomenon, which is clearly revealed in matter wave interferometry. It is often essential for the success of matter wave experiments, to achieve complete isolation of the interfering particle from its environment since any detailed information about the location of the object will destroy the interference. Especially for complex molecules with a rich structure and dynamics, the interaction between their internal motion and their center-of-mass motion has often been considered a serious obstacle for matter wave experiments. Now, a European collaboration shows how information about the internal molecular dynamics can be extracted in matter wave experiments without destroying quantum interference: an external electric field interacts with the molecule’s internal components and shifts the quantum wave pattern in a precisely measurable. Thus the internal molecular motion can be probed while the particle remains delocalized and quantum interference is still preserved.