Multiphoton processes in two-level atoms in two intense pump beams

The dynamical behavior of a two-level atom under the influence of two intense pump beams is examined. Exact equations for the nonlinear susceptibilities to all orders in the field strengths are derived. Numerical results for the nonlinear susceptibilities giving the absorption of the radiation from either of the pump beams and the generation of the four-wave mixing signal are given. The susceptibility for four-wave mixing, in addition to showing various saturation peaks, shows a peak at ω1=ω2 even in the case of radiative relaxation. Higher-order multiphoton peaks in the absorption spectra are found to be extremely sensitive to the temporal fluctuations in the pumps

Source of sediments and response of clay minerals, organic matter and metals to fluctuating environmental conditions in western Bay of Bengal

535-553  The sediment cores collected along three transects off the Mahanadi, Godavari and Krishna rivers were analyzed for spatial and temporal variations in grain size, clay minerals, total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), calcium carbonate, and selected metals (Al, Fe, Ti, Mn, Zn) to understand the provenance of sediments and the role of monsoons and dissolved oxygen in the preservation of organic elements and metals in recent past. Illite was the dominant mineral off Mahanadi and smectite off Godavari and Krishna that indicated their different sources, viz., felsic and mafic rocks, respectively. The high Fe/Al and Ti/Al content in shallow areas off Godavari and Krishna may have been added from the leaching of Red Beds and mafic rocks respectively. The TOC/TN molar ratio was above 8.00 in most samples that indicated the supply of organic matter from terrestrial sources. The sediment with less carbonate and organic matter revealed low biological productivity in the study area.   The relatively higher sand, elevated S/I+C ratio and metal content in the surface sediments and the lower section in majority of the cores indicated intensified rainfall and high runoff that brought increased oxygenated fresh water along with the higher metal influx. The reduced concentration of Mn/Al along with low S/I+C ratio and higher TOC and TN values in the 15 cm to 5 cm section in the cores off Godavari revealed weak rainfall which turned the water anoxic, as the available oxygen was consumed by the planktons. Under intensified OMZ, Mn/Al got depleted in reducing conditions and TOC, TN was better preserved

Collisional and saturation effects in multiphoton processes in the field of two pumps

The nonlinear response of a two-level system interacting with two pump beams of different frequencies is studied with a view to examine several recent experiments on nonlinear mixing of high orders, instabilities in homogeneously broadened lasers, and holes in homogeneous lines. Such a nonlinear response is calculated with use of the continued fractions given in our earlier work [J.Opt. Soc. Am. 81, 164 (1984)]. Saturation effects lead to the appearance of many structures at submultiples of the Rabi frequency. The origin of these subharmonics in nonlinear-response functions is explained. It is shown that collisions not only lead to hole burning at the line center for weak fields but can also lead in moderate fields to the appearance of structures at subharmonics of the Rabi frequency. Existence of collision-induced coherences similar to those in four-wave mixing is shown in six-wave mixing. Exact results for the degenerate nonlinear mixing of arbitrary order are presented for arbitrary values of field strengths. Saturating fields create holes at the line center of such nonlinear mixing signals. Gain profiles of two modes symmetrically displaced from line center are also given. Numerical results, with complete account of saturation and collisions, for a variety of nonlinear-response functions are presented

Kinetics & Mechanism of Oxidation of Aralkyl Amines by Peroxomonophosphoric Acid

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Incoherent scattering of 59.54 keV gamma rays for some rare earth elements at low photon momentum transfers

Incoherent scattering functions S(x, Z) for six rare earth elements were evaluated from accurately measured whole atom differential incoherent scattering cross sections for 59.54 keV γ-rays scattered at 30°, 45°, 60° and 90° scattering angles corresponding to 1.24, 1.84, 2.40 and 3.39 Å -1 photon momentum transfers. Our results for S(x, Z) are the first for these rare earth elements. © 2001 Elsevier Science Ltd. All rights reserved

O(4)-Invariant Formulation of the Nodal Liquid

We consider the O(4) symmetric point in the phase diagram of an electron system in which there is a transition between d_{x^2 - y^2} density-wave order and d_{x^2 - y^2} superconductivity. If the pseudospin $SU(2)\subset O(4)$ symmetry is disordered by quantum fluctuations, the Nodal Liquid can result. In this context, we (1) construct a pseudospin $\sigma$-model; (2) discuss its topological excitations; (3) point out the possibility of a {\it pseudospin-Peierls} state and (4) propose a phase diagram for the underdoped cuprate superconductors

Environment assisted entanglement enhancement

We consider dissipative atom-cavity systems and show that their collective dynamics leads to the maximization of entanglement for intermediate values of the cavity leakage parameter $\kappa$. We discuss possible ways the reservoir influences entanglement. We first consider the entanglement of a single two-level atom with a microwave cavity that is coupled to another cavity. We show that the atom-cavity entanglement can be made to increase with cavity leakage. We next show that the entanglement between two atoms passing successively through a cavity can be maximised for intermediate values of $\kappa$. We finally consider the micromaser where the increase of two-atom entanglement for stronger cavity-environment coupling is demonstrated for experimentally attainable values of the micromaser parameters.Comment: 4 pages, Revtex, 1 eps figure; minor changes to match with published versio

Production and Equilibration of the Quark-Gluon Plasma with Chromoelectric Field and Minijets

Production and equilibration of quark-gluon plasma are studied within the color flux-tube model, at the RHIC and LHC energies. Non-Abelian relativistic transport equations for quarks, antiquarks and gluons, are solved in the extended phase space which includes coordinates, momenta and color. Before the chromoelectric field is formed, hard and semihard partons are produced via minijets which provide the initial conditions necessary to solve the transport equations. The model predicts that in spite of the vast difference between the RHIC and LHC incident energies, once the local equilibrium is reached, the energy densities, the number densities and the temperatures at the two machines may not be very different from each other. The minijet input significantly alters the evolution of the deconfined matter, unless the color field is too strong. For the input parameters used here the equilibration time is estimated to be $\sim 1$ fm at RHIC and $\sim 0.5$ fm at LHC, measured from the instant when the two colliding nuclei have just passed through each other. The temperature at equilibration is found to be $\sim 250$ MeV at RHIC and $\sim 300$ MeV at LHC.Comment: version to appear in Phys. Rev. C; discussion enlarged to include comparison with other models; conclusions unchanged; 14 single-spaced pages + 8 ps figure

Non-abelian statistics of half-quantum vortices in p-wave superconductors

Excitation spectrum of a half-quantum vortex in a p-wave superconductor contains a zero-energy Majorana fermion. This results in a degeneracy of the ground state of the system of several vortices. From the properties of the solutions to Bogoliubov-de-Gennes equations in the vortex core we derive the non-abelian statistics of vortices identical to that for the Moore-Read (Pfaffian) quantum Hall state.Comment: 5 pages, 3 figures, REVTeX, epsf. Reference adde

Efficient fiber-optical interface for nanophotonic devices

We demonstrate a method for efficient coupling of guided light from a single mode optical fiber to nanophotonic devices. Our approach makes use of single-sided conical tapered optical fibers that are evanescently coupled over the last ~10 um to a nanophotonic waveguide. By means of adiabatic mode transfer using a properly chosen taper, single-mode fiber-waveguide coupling efficiencies as high as 97(1)% are achieved. Efficient coupling is obtained for a wide range of device geometries which are either singly-clamped on a chip or attached to the fiber, demonstrating a promising approach for integrated nanophotonic circuits, quantum optical and nanoscale sensing applications.Comment: 7 pages, 4 figures, includes supplementary informatio