Evaporative cooling of an atomic beam

We present a theoretical analysis of the evaporative cooling of an atomic beam propagating in a magnetic guide. Cooling is provided by transverse evaporation. The atomic dynamics inside the guide is analyzed by solving the Boltzmann equation with two different approaches: an approximate analytical ansatz and a Monte-Carlo simulation. Within their domain of validity, these two methods are found to be in very good agreement with each other. They allow us to determine how the phase-space density and the flux of the beam vary along its direction of propagation. We find a significant increase for the phase-space density along the guide for realistic experimental parameters. By extrapolation, we estimate the length of the beam needed to reach quantum degeneracy.Comment: 13 pages, 7 figures, to be published in EPJ D, revised versio

Retroactive quantum jumps in a strongly-coupled atom-field system

We investigate a novel type of conditional dynamic that occurs in the strongly-driven Jaynes-Cummings model with dissipation. Extending the work of Alsing and Carmichael [Quantum Opt. {\bf 3}, 13 (1991)], we present a combined numerical and analytic study of the Stochastic Master Equation that describes the system's conditional evolution when the cavity output is continuously observed via homodyne detection, but atomic spontaneous emission is not monitored at all. We find that quantum jumps of the atomic state are induced by its dynamical coupling to the optical field, in order retroactively to justify atypical fluctuations in ocurring in the homodyne photocurrent.Comment: 4 pages, uses RevTex, 5 EPS figure

Dark-Bright Solitons in Inhomogeneous Bose-Einstein Condensates

We investigate dark-bright vector solitary wave solutions to the coupled non-linear Schr\"odinger equations which describe an inhomogeneous two-species Bose-Einstein condensate. While these structures are well known in non-linear fiber optics, we show that spatial inhomogeneity strongly affects their motion, stability, and interaction, and that current technology suffices for their creation and control in ultracold trapped gases. The effects of controllably different interparticle scattering lengths, and stability against three-dimensional deformations, are also examined.Comment: 5 pages, 5 figure

PHYSIOLOGICAL ROLE OF HUNTERIA UMBELLATA FRUIT EXTRACT ON HORMONAL AND RENAL PROFILE IN CADMIUM INDUCED TOXICITY MALE WISTAR RATS

The present study was design with an objective to investigate the toxicity level of cadmium chloride on hormonal and biochemical markers and the restoration strength of Hunteria umbellata aqueous fruit extract administered at various dosage level of treatment in induced male wistar rats. The parameters investigated includes LH,FSH, Testosterone, Prolactin, Urea, Creatinine, and Uric acid following 0.07ml and 0.06ml single dose cdcl₂ induction of group2 and group3.However group4 was administered 0.03ml cdcl₂ daily while group1 serve as the control.Group2 was treated at 400mg/kg and group3 at 200mg/kg extract daily while group4 received no treatment but feed  and water ad libidum.Results from this study shows higher FSH (0.52 m/u/ml), LH (1.32 m/u/ml) and Prolactin (1.17ng/ml) among group3 treated at 200mg/kg extract of the Hunteria umbellata fruit. This was closely followed by group2 treated at 400mg/kg body weight ie LH (0.74 m/u/ml), Prolactin (1.04ng/ml) compared with group4 FSH of (0.25 m/u/ml), LH (0.37 m/u/ml) and control. The testosterone level was higher in group2 (4.65 ng/ml) compared with other groups. The study shows higher renal markers in group4 administered cdcl₂ without treatment. However in group2 treated at 400mg/kg extract had decreased renal markers followed by group3 treated at 200mg/kg extract.ie results from this study further indicate higher renal indices among group4 administered oral cdcl₂ daily with urea having (10.70mmol/l), Creatinine (178.5µmol/l) and uric acid (430.0µmol/l) compared with the control group of (9.6mmol/l),(165µmol/l) and (375µmol/l) respectively. This study have shown clearly the physio-pharmacological effect of Hunteria umbellata fruit extract in increasing glomerullar filtration rate to clear off these parameters from the blood and restore normal renal function

Detection of vorticity in Bose-Einstein condensed gases by matter-wave interference

A phase-slip in the fringes of an interference pattern is an unmistakable characteristic of vorticity. We show dramatic two-dimensional simulations of interference between expanding condensate clouds with and without vorticity. In this way, vortices may be detected even when the core itself cannot be resolved.Comment: 3 pages, RevTeX, plus 6 PostScript figure

Ion Temperatures in the Low Solar Corona: Polar Coronal Holes at Solar Minimum

In the present work we use a deep-exposure spectrum taken by the SUMER spectrometer in a polar coronal hole in 1996 to measure the ion temperatures of a large number of ions at many different heights above the limb between 0.03 and 0.17 solar radii. We find that the measured ion temperatures are almost always larger than the electron temperatures and exhibit a non-monotonic dependence on the charge-to-mass ratio. We use these measurements to provide empirical constraints to a theoretical model of ion heating and acceleration based on gradually replenished ion-cyclotron waves. We compare the wave power required to heat the ions to the observed levels to a prediction based on a model of anisotropic magnetohydrodynamic turbulence. We find that the empirical heating model and the turbulent cascade model agree with one another, and explain the measured ion temperatures, for charge-to-mass ratios smaller than about 0.25. However, ions with charge-to-mass ratios exceeding 0.25 disagree with the model; the wave power they require to be heated to the measured ion temperatures shows an increase with charge-to-mass ratio (i.e., with increasing frequency) that cannot be explained by a traditional cascade model. We discuss possible additional processes that might be responsible for the inferred surplus of wave power.Comment: 11 pages (emulateapj style), 10 figures, ApJ, in press (v. 691, January 20, 2009

On the stability of standing matter waves in a trap

We discuss excited Bose-condensed states and find the criterion of dynamical stability of a kink-wise state, i.e., a standing matter wave with one nodal plane perpendicular to the axis of a cylindrical trap. The dynamical stability requires a strong radial confinement corresponding to the radial frequency larger than the mean-field interparticle interaction. We address the question of thermodynamic instability related to the presence of excitations with negative energy.Comment: 4 pages, 3 figure

Dark-State Polaritons in Electromagnetically Induced Transparency

We identify form-stable coupled excitations of light and matter (``dark-state polaritons'') associated with the propagation of quantum fields in Electromagnetically Induced Transparency. The properties of the dark-state polaritons such as the group velocity are determined by the mixing angle between light and matter components and can be controlled by an external coherent field as the pulse propagates. In particular, light pulses can be decelerated and ``trapped'' in which case their shape and quantum state are mapped onto metastable collective states of matter. Possible applications of this reversible coherent-control technique are discussed.Comment: 4 pages, 2 figure

Many-body solitons in a one-dimensional condensate of hard core bosons

A mapping theorem leading to exact many-body dynamics of impenetrable bosons in one dimension reveals dark and gray soliton-like structures in a toroidal trap which is phase-imprinted. On long time scales revivals appear that are beyond the usual mean-field theory