Self-trapping mechanisms in the dynamics of three coupled Bose-Einstein condensates

We formulate the dynamics of three coupled Bose-Einstein condensates within a semiclassical scenario based on the standard boson coherent states. We compare such a picture with that of Ref. 1 and show how our approach entails a simple formulation of the dimeric regime therein studied. This allows to recognize the parameters that govern the bifurcation mechanism causing self-trapping, and paves the way to the construction of analytic solutions. We present the results of a numerical simulation showing how the three-well dynamics has, in general, a cahotic behavior.Comment: 4 pages, 5 figure

Moving lattice kinks and pulses: an inverse method

We develop a general mapping from given kink or pulse shaped travelling-wave solutions including their velocity to the equations of motion on one-dimensional lattices which support these solutions. We apply this mapping - by definition an inverse method - to acoustic solitons in chains with nonlinear intersite interactions, to nonlinear Klein-Gordon chains, to reaction-diffusion equations and to discrete nonlinear Schr\"odinger systems. Potential functions can be found in at least a unique way provided the pulse shape is reflection symmetric and pulse and kink shapes are at least $C^2$ functions. For kinks we discuss the relation of our results to the problem of a Peierls-Nabarro potential and continuous symmetries. We then generalize our method to higher dimensional lattices for reaction-diffusion systems. We find that increasing also the number of components easily allows for moving solutions.Comment: 15 pages, 5 figure

Localization from quantum interference in one-dimensional disordered potentials

We show that the tails of the asymptotic density distribution of a quantum wave packet that localizes in the the presence of random or quasiperiodic disorder can be described by the diagonal term of the projection over the eingenstates of the disordered potential. This is equivalent of assuming a phase randomization of the off-diagonal/interference terms. We demonstrate these results through numerical calculations of the dynamics of ultracold atoms in the one-dimensional speckle and quasiperiodic potentials used in the recent experiments that lead to the observation of Anderson localization for matter waves [Billy et al., Nature 453, 891 (2008); Roati et al., Nature 453, 895 (2008)]. For the quasiperiodic case, we also discuss the implications of using continuos or discrete models.Comment: 5 pages, 3 figures; minor changes, references update

Nonlinear Lattice Waves in Random Potentials

Localization of waves by disorder is a fundamental physical problem encompassing a diverse spectrum of theoretical, experimental and numerical studies in the context of metal-insulator transition, quantum Hall effect, light propagation in photonic crystals, and dynamics of ultra-cold atoms in optical arrays. Large intensity light can induce nonlinear response, ultracold atomic gases can be tuned into an interacting regime, which leads again to nonlinear wave equations on a mean field level. The interplay between disorder and nonlinearity, their localizing and delocalizing effects is currently an intriguing and challenging issue in the field. We will discuss recent advances in the dynamics of nonlinear lattice waves in random potentials. In the absence of nonlinear terms in the wave equations, Anderson localization is leading to a halt of wave packet spreading. Nonlinearity couples localized eigenstates and, potentially, enables spreading and destruction of Anderson localization due to nonintegrability, chaos and decoherence. The spreading process is characterized by universal subdiffusive laws due to nonlinear diffusion. We review extensive computational studies for one- and two-dimensional systems with tunable nonlinearity power. We also briefly discuss extensions to other cases where the linear wave equation features localization: Aubry-Andre localization with quasiperiodic potentials, Wannier-Stark localization with dc fields, and dynamical localization in momentum space with kicked rotors.Comment: 45 pages, 19 figure

Relaxation channels of two-vibron bound states in \alpha-helix proteins

Relaxation channels for two-vibron bound states in an anharmonic alpha-helix protein are studied. It is pointed out that the relaxation originates in the interaction between the dressed anharmonic vibrons and the remaining phonons. This interaction is responsible for the occurrence of transitions between two-vibron eigenstates mediated by both phonon absorption and phonon emission. At biological temperature, it is shown that the relaxation rate does not significantly depends on the nature of the two-vibron state involved in the process. Therefore, the lifetime for both bound and free states is of the same order of magnitude and ranges between 0.1 and 1.0 ps for realistic parameters. By contrast, the relaxation channels strongly depend on the nature of the two-vibron states which is a consequence of the breather-like behavior of the two-vibron bound states.Comment: octobre 2003 - soumis Phys. Rev.

High prevalence of peribronchial focal lesions of airway invasive aspergillosis in hematological cancer patients with prolonged neutropenia.

The aim of this study is to characterize chest CT findings of neutropenic patients with proven/probable invasive pulmonary aspergillosis (IPA). Hematological cancer patients admitted to our institution (2007-2017) were retrospectively enrolled if the diagnostic criteria of proven/probable IPA during the neutropenia were met (EORTC/MSG). Galactomannan (GM) was routinely measured in serum and chest CT-scan was routinely performed in case of recurrent/persistent fever. Bronchoscopy was performed in case of chest CT-scan abnormalities. Chest CT-scan and GM dosage were analyzed at the time of IPA suspicion. Chest lesions were classified using a clinical report form by two expert radiologists. 35 patients were identified. Peribronchial focal lesions were observed in 29 IPA (82.9%) by the first radiologist and in 31 (88.5%) by the second (k = 0.768). 12 weeks mortality was 20%. Peribronchial focal lesions are a common finding in early-IPA whatever the GM value during neutropenia and our findings reinforce the efficiency of a preemptive approach. Peribronchial focal lesions, which are classically described in airway invasive aspergillosis, are a common finding in early-IPA in hematological cancer patients with prolonged neutropenia regardless of the GM value, and such peribronchial lesions should reinforce the possibility of IPA

Electron motion in a Holstein molecular chain in an electric field

A charge motion in an electric field in a Holstein molecular chain is modeled in the absence of dissipation. It is shown that in a weak electric field a Holstein polaron moves uniformly experiencing small oscillations of its shape. These oscillations are associated with the chain’s discreteness and caused by the presence of Peierls-Nabarro potential there. The critical value of the electric field intensity at which the moving polaron starts oscillating at Bloch frequency is found. It is shown that the polaron can demonstrate Bloch oscillations retaining its shape. It is also shown that a breathing mode of Bloch oscillations can arise. In all cases the polaron motion along the chain is infinite. Copyright EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg 2011