Stimulated Raman adiabatic passage analogs in classical physics

Stimulated Raman adiabatic passage (STIRAP) is a well established technique for producing coherent population transfer in a three-state quantum system. We here exploit the resemblance between the Schrodinger equation for such a quantum system and the Newton equation of motion for a classical system undergoing torque to discuss several classical analogs of STIRAP, notably the motion of a moving charged particle subject to the Lorentz force of a quasistatic magnetic field, the orientation of a magnetic moment in a slowly varying magnetic field, the Coriolis effect and the inertial frame dragging effect. Like STIRAP, those phenomena occur for counterintuitively ordered field pulses and are robustly insensitive to small changes in the interaction properties

Preparation of nondegenerate coherent superpositions in a three-state ladder system assisted by Stark Shifts

We propose a technique to prepare coherent superpositions of two nondegenerate quantum states in a three-state ladder system, driven by two simultaneous fields near resonance with an intermediate state. The technique, of potential application to enhancement of nonlinear processes, uses adiabatic passage assisted by dynamic Stark shifts induced by a third laser field. The method offers significant advantages over alternative techniques: (\i) it does not require laser pulses of specific shape and duration and (\ii) it requires less intense fields than schemes based on two-photon excitation with non-resonant intermediate states. We discuss possible experimental implementation for enhancement of frequency conversion in mercury atoms.Comment: 22 pages, 8 figures, 1 table, submitted to PHys. Rev.

Photoionization Suppression by Continuum Coherence: Experiment and Theory

We present experimental and theoretical results of a detailed study of laser-induced continuum structures (LICS) in the photoionization continuum of helium out of the metastable state 2s $^1S_0$. The continuum dressing with a 1064 nm laser, couples the same region of the continuum to the {4s $^1S_0$} state. The experimental data, presented for a range of intensities, show pronounced ionization suppression (by as much as 70% with respect to the far-from-resonance value) as well as enhancement, in a Beutler-Fano resonance profile. This ionization suppression is a clear indication of population trapping mediated by coupling to a contiuum. We present experimental results demonstrating the effect of pulse delay upon the LICS, and for the behavior of LICS for both weak and strong probe pulses. Simulations based upon numerical solution of the Schr\"{o}dinger equation model the experimental results. The atomic parameters (Rabi frequencies and Stark shifts) are calculated using a simple model-potential method for the computation of the needed wavefunctions. The simulations of the LICS profiles are in excellent agreement with experiment. We also present an analytic formulation of pulsed LICS. We show that in the case of a probe pulse shorter than the dressing one the LICS profile is the convolution of the power spectra of the probe pulse with the usual Fano profile of stationary LICS. We discuss some consequences of deviation from steady-state theory.Comment: 29 pages, 17 figures, accepted to PR

Spatial and Temporal Distribution of Essential and Non-Essential Elements Recorded in Western Arctic Bowhead Whales (Balaena mysticetus)

Western Arctic bowhead whales, Balaena mysticetus, migrate annually among the Bering, Chukchi, and Beaufort seas. Foraging along their route, they use keratinous baleen to filter microscopic zooplankton from the water column. A single baleen plate from an adult bowhead whale grows continuously and stores 20+ years of dietary and environmental data. This study utilized induced coupled plasma-mass spectrometry (ICP-MS) to evaluate concentrations of 14 essential and non-essential elements in baleen samples from nine subsistence-harvested whales, yielding continuous data from 1958–1999 (n=148). Stable isotope data previously reported on these samples provided information on location (Beaufort Sea; Bering/Chukchi seas), season (winter; summer), and year per sample. All 14 elements were detected in baleen: aluminum (Al), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), nickel (Ni), manganese (Mn), lead (Pb), selenium (Se), vanadium (V), zinc (Zn). The lowest concentrations of elements were found for As, Cd, V; the highest Al, Cu, Fe, and Zn. Fe and Mn varied coincidentally across the plates of whales from the 1990s. Se and Hg were significantly correlated (ρ=–0.398, p0.05). These data implied biomagnification, bioaccumulation, and/or toxicity with time, though further studies are necessary to confirm

Drip irrigation of plastic mulched strawberry using carbonated water - a greenhouse study

1994 Fall.Covers not scanned.Includes bibliographical references.Carbonated water irrigation enhanced yields of tomato, however, little is known about the mechanism of this response. Objectives were: 1.) determine if strawberry responds to irrigation with carbonated water and 2.) determine if yield increase, should it occur, is due to short-term soil pH optimization or air-soil atmospheric enrichment with CO2. Two different soils (2:1, perlite:soil) were used: a calcareous soil (5% CaCO3, pH 8.0), with a Zn content of 0.9 μg/g and a non-calcareous soil (< 1 % CaCO3, pH 6.4) with a Zn content of 8.4 μg/g. The carbonated water temporarily lowered the pH of the calcareous soil to 6.7 and the non-calcareous soil to 5.9, at both extremes of the optimal range (5.2-6.4) for strawberry. There was significant increase in above ground (1 cm) CO2 during irrigation. Also, a significant increase in soil CO2 was observed in the calcareous soil, carbonated water treatment over the noncalcareous, carbonated water treatment, which suggests carbonic acid played a role in lowering the surface pH of the calcareous soil from 8.0 to 6.7 shortly after each irrigation event. Application of carbonated water increased production of buds and open flowers at the P < 0.05 significance level. Carbonated water increased the production of marketable fruit (P < 0.10) as compared to the noncarbonated water considering both soils. In addition, there was greater crown dry weight and higher leaf chlorophyll content (P < 0.05) observed in plants irrigated with carbonated water. The magnitude of the response to carbonated water was similar for each soil. The noncalcareous soil had significantly greater accumulation of Zn in leaf tissue as compared to calcareous soil, considering both irrigation treatments. However, the calcareous soil, carbonated water irrigation treatment had a slight increase in the uptake of Zn over the calcareous, noncarbonated water treatment. Also, there was no significant difference in the uptake of Fe, Mn, or Cu in regard to irrigation treatments or soil type

Radiative, actively cooled panel tests results

The radiative, actively cooled panel designed to withstand a uniform incident heat flux of 136 kW/sq m to a 444 K surface temperature was evaluated. The test program consisted of preliminary static thermal mechanical loading and aerothermal flow tests. Test results are briefly discussed

Extension of the Morris-Shore transformation to multilevel ladders

We describe situations in which chains of N degenerate quantum energy levels, coupled by time-dependent external fields, can be replaced by independent sets of chains of length N, N-1,...,2 and sets of uncoupled single states. The transformation is a generalization of the two-level Morris-Shore transformation [J.R. Morris and B.W. Shore, Phys. Rev. A 27, 906 (1983)]. We illustrate the procedure with examples of three-level chains

Flutter at Mach 3 of thermally stressed panels and comparison with theory for panels with edge rotational restraint

Flutter at Mach 3 of thermally stressed flat isotropic panel

Diffusion-Induced Oscillations of Extended Defects

From a simple model for the driven motion of a planar interface under the influence of a diffusion field we derive a damped nonlinear oscillator equation for the interface position. Inside an unstable regime, where the damping term is negative, we find limit-cycle solutions, describing an oscillatory propagation of the interface. In case of a growing solidification front this offers a transparent scenario for the formation of solute bands in binary alloys, and, taking into account the Mullins-Sekerka instability, of banded structures