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

An atomic electron is prepared in a state closely analogous to Schr{umlt o}dinger{close_quote}s coherent superposition of {open_quote}{open_quote}live cat{close_quote}{close_quote} and {open_quote}{open_quote}dead cat.{close_quote}{close_quote} The electronic state is a coherent superposition of two spatially localized wave packets separated by approximately 0.4 {mu}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 {open_quote}{open_quote}cat state,{close_quote}{close_quote} and a Ramsey fringe measurement is used to verify the coherence of the superposition. {copyright} {ital 1996 The American Physical Society.}