Finding quantum lines of desire

What paths do quantum particles, such as atoms or photons, follow through quantum state space? Kater Murch of Washington University in St. Louis has used a superconducting quantum device to continuously and repeatedly record the paths the device took through quantum state space. From the cobweb of a million paths, a most likely path between two quantum states emerged, much as social trails emerge as people round off corners or cut across lawns between buildings. The research is featured on the cover of the July 31 issue of Nature.