We report measurements of the early-time momentum diffusion for the atom-optical delta-kicked rotor. In this experiment a Bose-Einstein condensate provides a source of ultracold atoms with an ultranarrow initial momentum distribution, which is then subjected to periodic pulses (or "kicks") using an intense far-detuned optical standing wave. We characterize the effect of varying the effective Planck's constant for the system, while keeping all other parameters fixed. The observed behavior includes both quantum resonances (ballistic energy growth) and antiresonances (re-establishment of the initial state). Our experimental results are compared with theoretical predictions.

We experimentally investigate the atom-optical delta-kicked harmonic oscillator for the case of nonlinearity due to collisional interactions present in a Bose-Einstein condensate. A Bose condensate of rubidium atoms tightly confined in a static harmonic magnetic trap is exposed to a one-dimensional optical standing-wave potential that is pulsed on periodically. We focus on the quantum anti-resonance case for which the classical periodic behavior is simple and well understood. We show that after a small number of kicks the dynamics is dominated by dephasing of matter wave interference due to the finite width of the condensate's initial momentum distribution.In addition, we demonstrate that the nonlinear mean-field interaction in a typical harmonically confined Bose condensate is not sufficient to give rise to chaotic behavior. The delta-kicked rotor is an extensively investigated system in the field of classical chaos theory. During the last decade great progress has been achieved in understanding quantum dynamics of a classically chaotic system using atom-optical techniques and cold atoms. From an experimental point of view, cold atoms in optical potentials [1,2,3,4,5] provide an ideal environment to explore quantum dynamics. To date, all experimental work has focused on linear atomic systems, (see, for example, [6,7,8,9] and references therein) where the quantum dynamics is stable due to the linearity of the Schrödinger equation. In stark contrast to the chaotic behavior of classical dynamics, the linear quantum systems exhibit anti-resonance (periodic motion), dynamical localization (quasi-periodic motion) or resonant dynamics [10,11].Recently, theoretical investigations have considered how the nonlinearity due to many-body (collisional) interactions in a Bose-Einstein condensate modifies the behavior of the atom-optical kicked rotor system, providing a route to chaotic dynamics. Gardiner et al. developed a theoretical formalism to treat the one-dimensional nonlinear kicked harmonic oscillator (a particular manifestation of the generic delta-kicked rotor) using GrossPitaevskii and Liouville-type equations to describe the dynamics of a Bose-Einstein condensate, and estimated the growth rate in the number of non-condensate particles [12]. Zhang et al. investigated the generalized quantum kicked rotor by considering a periodically kicked Bose condensate confined in a ring potential for the case of quantum anti-resonance [13]. As opposed to the familiar periodic behavior exhibited by a corresponding linear system, they predicted quasi-periodic variation in energy for a weak interaction strength and chaotic behavior for strong interactions.In this work we investigate the nonlinear delta-kicked harmonic oscillator by performing experiments on BoseEinstein condensates in a harmonic potential. A Bose condensate of rubidium atoms tightly confined in a static harmonic magnetic trap is exposed to a periodically pulsed one-dimensional optical standing-wave potential. Our focus is on the particular case of quantum antireso...

The photoabsorption spectrum of In II has been recorded in the 18-33 eV region using the dual laser plasma (DLP) technique. Transitions from the 4d105s2 ground state dominate the In II spectrum with some contribution from the metastable 3P2, 3P1 and 3P0 levels of the excited 4d105s5p configuration also observed. Transitions were identified by comparison with values obtained from multiconfiguration Hartree-Fock calculations.

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The photoabsorption spectrum of a tin laser-produced plasma has been recorded in the 23-33 eV region using the dual laser plasma technique. 4d→5p transitions from the 4d105s25p ground state of Sn II and from the 4d105s2 ground and 4d105s5p excited states of Sn III were observed and new features identified with the aid of multiconfiguration Hartree-Fock calculations. The relative intensities of transitions in Sn III indicate a departure from local thermodynamic equilibrium conditions in the absorbing plasma.