Measurements of Diffusion Resonances for the Atom Optics Quantum Kicked Rotor
Mary E. K. Williams, Mark Sadgrove, Andrew J. Daley, Richard Gray, S. M. Tan, A. S. Parkins, R. Leonhardt, Nelson L Christensen
Abstract
We present experimental observations of diffusion resonances for the quantum kicked rotor with weak decoherence. Cold caesium atoms are subject to a pulsed standing wave of near-resonant light, with spontaneous emission providing environmental coupling. The mean energy as a function of the pulse period is determined during the late-time diffusion period for a constant probability of spontaneous emission. Structure in the late-time energy is seen to increase with physical kicking strength. The observed structure is related to Shepelyansky's predictions of the initial quantum diffusion rates. Additional results of diffusion rates as a function of the effective Planck's constant are given, showing non-trivial behaviour in the quantum-to-classical transition regime.