Generation of entangled coherent states via cross-phase-modulation in a double electromagnetically induced transparency regime

The generation of an entangled coherent state is one of the most important ingredients of quantum information processing using coherent states. Recently, numerous schemes to achieve this task have been proposed. In order to generate travelling-wave entangled coherent states, cross-phase-modulation, optimized by optical Kerr effect enhancement in a dense medium in an electromagnetically induced transparency (EIT) regime, seems to be very promising. In this scenario, we propose a fully quantized model of a double-EIT scheme recently proposed [D. Petrosyan and G. Kurizki, Phys. Rev. A 65, 33 833 (2002)]: the quantization step is performed adopting a fully Hamiltonian approach. This allows us to write effective equations of motion for two interacting quantum fields of light that show how the dynamics of one field depends on the photon-number operator of the other. The preparation of a Schrodinger cat state, which is a superposition of two distinct coherent states, is briefly exposed. This is based on nonlinear interaction via double EIT of two light fields (initially prepared in coherent states) and on a detection step performed using a 50:50 beam splitter and two photodetectors. In order to show the entanglement of an entangled coherent state, we suggest to measure the joint quadrature variance of the field. We show that the entangled coherent states satisfy the sufficient condition for entanglement based on quadrature variance measurement. We also show how robust our scheme is against a low detection efficiency of homodyne detectors.

Preliminary Results of a Prospective Randomized Trial of Restrictive Versus Standard Fluid Regime in Elective Open Abdominal Aortic Aneurysm Repair

Background: Open abdominal aortic aneurysm (AAA) repair is associated with a significant morbidity (primarily respiratory and cardiac complications) and an overall mortality rate of 4% to 10%. We tested the hypothesis that perioperative fluid restriction would reduce complications and improve outcome after elective open AAA repair.

Experimental observations of the stress regime in unsaturated compacted clay when laterally confined

Construction processes often involve reformation of the landscape, which will inevitably encompass compaction of artificially placed soils. A common application of fill materials is their use as backfill in many engineering applications, for example behind a retaining wall. The post-construction behaviour of clay fills is complex with respect to stresses and deformation when the fills become saturated over time. Heavily compacted fills swells significantly more than the lightly compacted fills. This will produce enhanced lateral stresses if the fill is laterally restrained. The work presented in this paper examines how the stress regime in unsaturated clay fills changes with wetting under laterally restrained conditions. Specimens of compacted kaolin, with different initial conditions, were wetted to various values of suction under zero lateral strain at constant net overburden pressure which allowed the concept of K _{0 (the ratio between the net horizontal stress and the net vertical stress) to be examined. Tests were also carried out to examine the traditional concept of the earth pressure coefficient ‘at rest' under loading and unloading and its likely effects on the stress–strain properties. The results have shown that the stress regime (i.e. the lateral stress) changes significantly during wetting under laterally restrained conditions. The magnitude of the change is affected by the initial condition of the soil. The results have also indicated that the earth pressure coefficient ‘at rest' during loading (under the normally consolidated condition) is unaffected by suction and such loading conditions inevitably lead to the development of anisotropic stress–strain properties}

De novo generation of a non-segmented negative strand RNA virus with a bicistronic gene

Reverse genetics has facilitated the use of non-segmented negative strand RNA viruses (NNSV) as vectors. Currently, heterologous gene expression necessitates insertion of extra-numeral transcription units (ENTUs), which may alter the NNSV polar transcription gradient and attenuate growth relative to wildtype (Wt). We hypothesized that rescuing recombinant Sendai Virus (rSeV) with a bicistronic gene might circumvent this attenuation but still allow heterologous open reading frame (ORF) expression. Therefore, we used a 9-nucleotide sequence previously described with internal ribosome entry site (IRES) activity, which, when constructed as several repeats, synergistically increased the level of expression of the second cistron [Chappell, S.A., Edelman, G.M., Mauro, V.P., 2000. A 9-nt segment of a cellular mRNA can function as an internal ribosome entry site (IRES) and when present in linked multiple copies greatly enhances IRES activity. Proc. Natl. Acad. Sci. U.S.A. 97, 1536-1541]. We inserted the Renilla luciferase (rLuc) ORF, preceded by 1, 3 or 7 IRES copies, downstream of the SeV N ORF in an infectious clone. Corresponding rSeVs were successfully rescued. Interestingly, bicistronic rSeVs grew as fast as or faster than Wt rSeV. Furthermore, SeV gene transcription downstream of the N/rLuc gene was either equivalent to, or slightly enhanced, compared to Wt rSeV. Importantly, all rSeV/rLuc viruses efficiently expressed rLuc. IRES repetition increased rLuc expression at a multiplicity of infection of 0.1, although without evidence of synergistic enhancement. In conclusion, our approach provides a novel way of insertion and expression of foreign genes in NNSVs. (C) 2008 Elsevier B.V. All rights reserved.

Stability and dynamical behavior in a lake-model and implications for regime shifts in real lakes

A modified abstract version of the Comprehensive Aquatic Simulation Model (CASM) is found to exhibit three types of folded bifurcations due to nutrient loading. The resulting bifurcation diagrams account for nonlinear dynamics such as regime shifts and cyclic changes between clear-water state and turbid state that have actually been observed in real lakes. In particular, pulse-perturbation simulations based on the model presented suggest that temporal behaviors of real lakes after biomanipulations can be explained by pulse-dynamics in complex ecosystems, and that not only the amplitude (manipulated abundance of organisms) but also the phase (timing) is important for restoring lakes by biomanipulation. Ecosystem management in terms of possible irreversible changes in ecosystems induced by regime shifts is also discussed. (c) 2007 Elsevier B.V All rights reserved.

Pattern formation of chevrons in the conduction regime in homeotropically aligned liquid crystals

We report on chevrons (herringbonelike patterns) observed in homeotropically aligned liquid crystals with high electric conductivity. We focus our attention on two types of chevrons observed in the conduction regime. The threshold voltage and the characteristic double periodicity of chevrons (i.e., the short wavelength lambda(1) of the striated rolls and the long wavelength lambda(2) Of the chevron bands) have been measured as functions of the applied electric frequency f. With the aid of a crossed polarizer set, we have, in addition, determined the director field which shows a periodic in-plane rotation for our chevrons (with a wavelength lambda(2)) We arrived at the types of chevrons after qualitatively different bifurcation sequences with increasing voltage. The frequency dependence of lambda(2) also shows a qualitatively different behavior with respect to the two types of chevrons. The experimental results are discussed in terms of recent theoretical investigations.

Radiation-Pressure Acceleration of Ion Beams from Nanofoil Targets: The Leaky Light-Sail Regime

A new ion radiation-pressure acceleration regime, the "leaky light sail," is proposed which uses sub-skin-depth nanometer foils irradiated by circularly polarized laser pulses. In the regime, the foil is partially transparent, continuously leaking electrons out along with the transmitted laser field. This feature can be exploited by a multispecies nanofoil configuration to stabilize the acceleration of the light ion component, supplementing the latter with an excess of electrons leaked from those associated with the heavy ions to avoid Coulomb explosion. It is shown by 2D particle-in-cell simulations that a monoenergetic proton beam with energy 18 MeV is produced by circularly polarized lasers at intensities of just 10(19) W/cm(2). 100 MeV proton beams are obtained by increasing the intensities to 2 x 10(20) W/cm(2).

Dependence of the ion energy on the parameters of the laser pulse and target in the radiation-pressure-dominated regime of acceleration

When the dominant mechanism for ion acceleration is the laser radiation pressure, the conversion efficiency of the laser energy into the energy of relativistic ions may be very high. Stability analysis of a thin plasma layer accelerated by the radiation pressure shows that Raleigh-Taylor instability may enhance plasma inhomogeneity. In the linear stage of instability, the plasma layer decays into separate bunches, which are accelerated by the radiation pressure similarly to clusters accelerated under the action of an electromagnetic wave. The energy and luminosity of an ion beam accelerated in the radiation-pressure-dominated regime are calculated.

Enhanced Laser-Driven Ion Acceleration in the Relativistic Transparency Regime

We report on the acceleration of ion beams from ultrathin diamondlike carbon foils of thickness 50, 30, and 10 nm irradiated by ultrahigh contrast laser pulses at intensities of similar to 7 X 10(19) W/cm(2). An unprecedented maximum energy of 185 MeV (15 MeV/u) for fully ionized carbon atoms is observed at the optimum thickness of 30 nm. The enhanced acceleration is attributed to self-induced transparency, leading to strong volumetric heating of the classically overdense electron population in the bulk of the target. Our experimental results are supported by both particle-in-cell (PIC) simulations and an analytical model.