Experimental observation of high-order quantum accelerator modes.

Using a freely falling cloud of cold cesium atoms periodically kicked by pulses from a vertical standing wave of laser light, we present the first experimental observation of high-order quantum accelerator modes. This confirms the recent prediction by Fishman, Guarneri, and Rebuzzini [Phys. Rev. Lett.10.1103/PhysRevLett.89.084101 89, 084101 (2002)]. We also show how these accelerator modes can be identified with the stable regions of phase space in a classical-like chaotic system, despite their intrinsically quantum origin

Experimental Observation of Quantum Chaos in a Beam of Light

The manner in which unpredictable chaotic dynamics manifests itself in quantum mechanics is a key question in the field of quantum chaos. Indeed, very distinct quantum features can appear due to underlying classical nonlinear dynamics. Here we observe signatures of quantum nonlinear dynamics through the direct measurement of the time-evolved Wigner function of the quantum-kicked harmonic oscillator, implemented in the spatial degrees of freedom of light. Our setup is decoherence-free and we can continuously tune the semiclassical and chaos parameters, so as to explore the transition from regular to essentially chaotic dynamics. Owing to its robustness and versatility, our scheme can be used to experimentally investigate a variety of nonlinear quantum phenomena. As an example, we couple this system to a quantum bit and experimentally investigate the decoherence produced by regular or chaotic dynamics.Comment: 7 pages, 5 figure

Proportion (mean ±1 SE) of experimentally-administered cercariae demonstrating a preference for a host species.

<p>Values for those species not sharing a letter are significantly different based on Fisher’s least significant difference tests.</p

Proportion (mean ±1 SE) of experimentally-administered cercariae successfully infecting each host species.

<p>Values for those species not sharing a letter are significantly different based on Fisher’s least significant difference test.</p

Focal species and experimental host-selection apparatus.

<p><b>a)</b> Neutral red-stained focal parasite’s armatae cercaria; scale bar = 0.5 mm. <b>b)</b> four focal amphibian species with average larval period length (days from hatching to metamorphosis) in upper right corner. <b>c)</b> Host selection apparatus. Cercariae were placed in the center vial and one tadpole was placed inside of each of four pipette bulbs. Photo credit: a) Scott Egan, b–c) Ron Altig, d) United States Geological Survey.</p