Atoms can be excited so as to occupy several energy levels at the same time. Such "Rydberg" atoms and their multitude of levels might one day be employed for encoding and manipulating information in a quantum computer. This movie is a time sequence showing the measured wave packet in a cesium atom. The fuzzy patch indiates the probable position and momentum of the excited electron. Its size is dictated by Heisenberg's Uncertainty principle; that is, both its position and momentum are shown here, but they cannot be determined simultaneously.
This research is reported by Philip Bucksbaum at the CLEO meeting.