Dephasing of Stark wave packets induced by colored noise

The time evolution of Stark wave packets in Rydberg atoms under the influence of colored noise is analyzed. The Stark wave packets are generated by exposing K(350p) Rydberg atoms to an electric field step. Their time evolution is monitored using a half-cycle probe pulse that is applied after a variable time delay. The noise is generated by randomly modulating the amplitude of the static field. We show that noise results in an enhanced and irreversible dephasing of Stark quantum beats, as monitored by the damping of the beat amplitude. This source of decoherence is most effective when the characteristic frequency of the noise power spectrum matches the orbital frequency of the Rydberg electron. Noise driven resonant Δn=1 transitions broaden the energy distribution thereby accelerating the dephasing.