Excitation of an Atomic Electron to a Coherent Superposition of Macroscopically Distinct States

Abstract

An atomic electron is prepared in a state closely analogous to Schr\"odinger's coherent superposition of ``live cat'' and ``dead cat.'' The electronic state is a coherent superposition of two spatially localized wave packets separated by approximately $0.4\ensuremath{\mu}\mathrm{m}$ at the opposite extremes of a Kepler orbit. State-selective ionization is used to verify that only every other atomic level is populated in the ``cat state,'' and a Ramsey fringe measurement is used to verify the coherence of the superposition.