Decoherence of high-ℓ Rydberg wave packets

Abstract

Quantum revivals in very-high-n (n ∼ 300) high-ℓ Rydberg wave packets generated from parent np states are used to examine decoherence induced by the application of ‘coloured’ noise from a random pulse generator and by collisions. In the absence of external perturbations, the high-ℓ wave packets maintain their coherence for periods ∼ 1 µs, i.e. for many hundreds of orbits. This coherence can be destroyed on sub-microsecond timescales by the application of even very small amounts of electrical noise at a rate that depends markedly on the spectral characteristics of the noise. In contrast, measurements over similar timescales with CO2 target gas densities of ∼ 1011 cm−3 provided no evidence of collisional dephasing. The mechanisms responsible for decoherence are discussed with the aid of classical and quantum simulations. The results of these simulations are in good accord with the experimental data.