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Atoms in high-lying (n > 300) Rydberg states permit the engineering of electronic wavefunctions using carefully-tailored sequences of short electric field pulses whose characteristic times (duration and/or rise/fall times) are less than the classical Kepler orbital period, ~ 4.3 ns at n ~ 300. The level of control that can be exercised is illustrated by protocols developed to create localized wavepackets moving in near-circular "Bohr-like" orbits about the nucleus and precisely manipulate their n distributions. The extraction of detailed information on the density matrix of near-circular Rydberg wavepackets through Fourier analysis of the quantum beat and quantum revival signals is demonstrated. This is facilitated by the remarkably long coherence times associated with circular wave packets which enables the preservation and read-out of phase information encoded in this matrix. The power of this method is illustrated by determining the angular localization of the components of the wavepacket. Such information, however, can be lost through decoherence. Experiment shows that while decoherence induced by collisions is slow the application of even very small amounts of "colored" electrical noise can lead to rapid decoherence. The physical processes underlying the various control protocols are discussed with reference to classical trajectory and "quantized" classical trajectory Monte Carlo simulations.
† research undertaken in collaboration with B. Wyker, J.J. Mestayer, C. O. Reinhold, S. Yoshida, and J Burgdörfer |
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