570 research outputs found
Dynamics of bright matter wave solitons in a quasi 1D Bose-Einstein condensate with a rapidly varying trap
The dynamics of a bright matter wave soliton in a quasi 1D Bose-Einstein
condensate with periodically rapidly varying trap is considered. The governing
equation is derived based on averaging over fast modulations of the
Gross-Pitaevskii (GP) equation. This equation has the form of GP equation with
effective potential of more complicated structure than unperturbed trap. For
the case of inverted (expulsive) quadratic trap corresponding to unstable GP
equation, the effective potential can be stable. For the bounded in space trap
potential it is showed that the bifurcation exists, i.e.,the single well
potential bifurcates to the triple well effective potential. Stabilization of
BEC cloud on-site state in the temporary modulated optical lattice is found.
(analogous to the Kapitza stabilization of the pendulum). The predictions of
the averaged GP equation are confirmed by the numerical simulations of GP
equation with rapid perturbations.Comment: 15 pages, 4 figure
Instabilities of wave function monopoles in Bose-Einstein condensates
We present analytic and numerical results for a class of monopole solutions
to the two-component Gross-Pitaevski equation for a two-species Bose condensate
in an effectively two-dimensional trap. We exhibit dynamical instabilities
involving vortex production as one species pours through another, from which we
conclude that the sub-optical sharpness of potentials exerted by matter waves
makes condensates ideal tools for manipulating condensates. We also show that
there are two equally valid but drastically different hydrodynamic descriptions
of a two-component condensate, and illustrate how different phenomena may
appear simpler in each.Comment: 4 pages, 9 figures (compressed figures become legible when zoomed or
when paper is actually printed
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
Dissipative dynamics of a kink state in a Bose-condensed gas
We develop a theory of dissipative dynamics of a kink state in a
finite-temperature Bose-condensed gas. We find that due to the interaction with
the thermal cloud the kink state accelerates towards the velocity of sound and
continuously transforms to the ground-state condensate. We calculate the
life-time of a kink state in a trapped gas and discuss possible experimental
implications.Comment: 4 pages, RevTe
Dynamical Cooling of Trapped Gases I: One Atom Problem
We study the laser cooling of one atom in an harmonic trap beyond the
Lamb-Dicke regime. By using sequences of laser pulses of different detunings we
show that the atom can be confined into just one state of the trap, either the
ground state or an excited state of the harmonic potential. The last can be
achieved because under certain conditions an excited state becomes a dark
state. We study the problem in one and two dimensions. For the latter case a
new cooling mechanism is possible, based on the destructive interference
between the effects of laser fields in different directions, which allows the
creation of variety of dark states. For both, one and two dimensional cases,
Monte Carlo simulations of the cooling dynamics are presented.Comment: LaTeX file with 8 pages, 7 eps figures. Submitted to Phys. Rev.
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
Cat States and Single Runs for the Damped Harmonic Oscillator
We discuss the fate of initial states of the cat type for the damped harmonic
oscillator, mostly employing a linear version of the stochastic Schr\"odinger
equation. We also comment on how such cat states might be prepared and on the
relation of single realizations of the noise to single runs of experiments.Comment: 18, Revte
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
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