Determination of bifurcations from recurrence peaks of electronic wavepackets in an electric field

A new and simple way to determine the bifurcations of electron orbits in an electric field is presented. From the quantum-mechanical wavepacket motion the classical energies at which new orbits bifurcate from the uphill and downhill orbits are obtained. This is an application of the inverse correspondence principle, since the discrete quantum spectrum is used to calculate classical features of the system. It is shown that at every bifurcation the periods of wavepacket motion in the radial and angular-momentum coordinate are commensurable. Therefore, all recurrences seen in electronic wavepacket experiments with Rydberg atoms in an electric field are the direct result of these bifurcations. To illustrate our point, experimental spectra before and after the bifurcation of the so-called ²/₃ orbit are presented.