Search results for "Cascade"

Electromagnetically induced transparency in Doppler-broadened three-level systems with resonant standing-wave drive

2000

We study electromagnetically induced transparency for a probe travelling-wave (TW) laser field in closed Doppler-broadened three-level systems driven by a resonant standing-wave (SW) laser field of moderate intensity (its Rabi frequencies are smaller than the Doppler width of the driven transition). We show that probe windows of transparency occur only for values of the probe-to-drive field frequency ratio R close to half-integer values. For optical transitions and typical values of Doppler broadening for atoms in a vapor cell, we show that for R > 1 a SW drive field is appreciably more efficient than a TW driving in inducing probe transparency. As an example, we consider parameters for a r…

Types I and II intermittencies in a cascade laser model

1995

Abstract We report on types I and II intermittencies found in a cascade laser model. A continuous transition from one to another type of intermittency, which involves the coexistence of both types of laminar phases within the same time series, is found. Type II intermittency has special characteristics such as its origin at a frequency locked two-torus. When frequency unlocked this torus bifurcates to a three-torus, further giving rise to a type II intermittent like behaviour with new features during the laminar phases.

High-Spin States in204Bi and the Question of Many-Nucleon Configuration Mixing

1981

The properties of high-spin levels in 204Bi have been studied using conventional in-beam γ-ray and conversion-electron spectroscopy on the products of the reactions 205Tl(α, 5n) 204Bi and 203Tl(α, 3n) 204Bi. The yrast cascade is followed to a 19+ level at 3808 keV and several non-yrast levels in the spin interval J = 9-16 are reported. The energies of the levels in 204Bi were calculated within the shell-model frame of multi-nucleon states, and the agreement is found to be good. A previously reported T1/2 = 1 ms isomeric state is shown to have a main configuration πh9/2ν(j-2)0+(i13/2-2)12+f5/2-1 and a spin-parity 17+. The configuration mixing for the neutron-hole components of the wave funct…

Central region in relativistic heavy ion collisions; results from hydrodynamic calculations and cascade simulation

1988

Results of three dimensional hydrodynamic calculations with boost invariant longitudinal expansion are presented with special emphasis on the transverse momentum spectra of hadrons and production rates of dileptons. The effect and signatures of transverse collective motion are discussed in detail. The hydrodynamic results which are based on the assumption of the existence of a first order phase transition and formation of an equilibrium mixed phase are compared with cascade simulation where the mixed phase is modelled in terms of plasma droplets embedded in a pion gas. The comparison shows a great deal of similarity between the two approaches lending further support for the hydrodynamic app…

Universal spectral dynamics of modulation instability : theory, simulation, experiment

2011

A central process of nonlinear fibre optics is modulation instability (MI), where weak perturbations on a continuous wave are amplified to generate a parametric cascade of spectral sidebands. Although studied for many years, it has only been recently appreciated that MI dynamics can be described analytically by Akhmediev breather (AB) solutions to the nonlinear Schrodinger equation (NLSE) [1]. This has led to important results, including the first observation of the Peregrine Soliton [2]. AB theory has also shown that the spectral amplitudes at the peak of the MI gain curve yield a characteristic log-triangular spectrum, providing new insight into the initial phase of supercontinuum generat…

Atomic Coherence Effects in Doppler-Broadened Three-Level Systems with Standing-Wave Drive

2001

We study atomic coherence effects (e.g., electromagnetically induced transparency, EIT, and amplification without inversion, AWI) for a probe travelling-wave (TW) laser field in closed Doppler-broadened three-level systems driven by a standingwave (SW) laser field of moderate intensity (its Rabi frequencies are smaller than the Doppler width of the driven transition). We show that probe windows of transparency occur only for values of the probe to drive field frequency ratio R close to half integer values. For optical transitions and typical values of Doppler broadening for atoms in a vapor cell, we show that for R > 1 a SW drive field is appreciably more efficient than a TW drive in induci…

Cascade coherence transfer and magneto-optical resonances at 455 nm excitation of Cesium

2010

We present and experimental and theoretical study of nonlinear magneto-optical resonances observed in the fluorescence to the ground state from the 7P_{3/2} state of cesium, which was populated directly by laser radiation at 455 nm, and from the 6P_{1/2} and 6P_{3/2} states, which were populated via cascade transitions that started from the 7P_{3/2} state and passed through various intermediate states. The laser-induced fluorescence (LIF) was observed as the magnetic field was scanned through zero. Signals were recorded for the two orthogonal, linearly polarized components of the LIF. We compared the measured signals with the results of calculations from a model that was based on the optica…

Type-II intermittency in a cascade laser model

2005

Master equation for cascade quantum channels: a collisional approach

2012

It has been recently shown that collisional models can be used to derive a general form for the master equations which describe the reduced time evolution of a composite multipartite quantum system, whose components "propagate" in an environmental medium which induces correlations among them via a cascade mechanism. Here we analyze the fundamental assumptions of this approach showing how some of them can be lifted when passing into a proper interaction picture representation.

Observation of inclined EeV air showers with the radio detector of the Pierre Auger Observatory

2018

With the Auger Engineering Radio Array (AERA) of the Pierre Auger Observatory, we have observed the radio emission from 561 extensive air showers with zenith angles between 60 and 84. In contrast to air showers with more vertical incidence, these inclined air showers illuminate large ground areas of several km2 with radio signals detectable in the 30 to 80 MHz band. A comparison of the measured radio-signal amplitudes with Monte Carlo simulations of a subset of 50 events for which we reconstruct the energy using the Auger surface detector shows agreement within the uncertainties of the current analysis. As expected for forward-beamed radio emission undergoing no significant absorption or sc…