Search results for "Dissipative system"
showing 10 items of 195 documents
Dynamical Processes in Open Quantum Systems from a TDDFT Perspective: Resonances and Electron Photoemission
2015
We present a review of different computational methods to describe time-dependent phenomena in open quantum systems and their extension to a density-functional framework. We focus the discussion on electron emission processes in atoms and molecules addressing excited-state lifetimes and dissipative processes. Initially we analyze the concept of an electronic resonance, a central concept in spectroscopy associated with a metastable state from which an electron eventually escapes (electronic lifetime). Resonances play a fundamental role in many time-dependent molecular phenomena but can be rationalized from a time-independent context in terms of scattering states. We introduce the method of c…
Extended irreversible thermodynamics of liquid helium II
1993
In this work a macroscopic monofluid theory of liquid helium II, which is based on the extended irreversible thermodynamics, is formulated both in the presence and in the absence of dissipative phenomena. The work is a generalization of previous papers, where the extended thermodynamics of an ideal monoatomic fluid was applied to liquid helium II. It is shown that the behavior of helium II can be described by means of an extended thermodynamic theory where four fields, namely density, temperature, velocity, and heat flux are involved as independent fields. In the presence of dissipative phenomena, constitutive relations for the trace and the deviator of the nonequilibrium stress tensor are …
Dissipative solitons and their interactions
2007
Coupled soliton pairs in nonlinear dissipative systems can exist in various forms. They can be stationary, or they can pulsate periodically, quasi-periodically or chaotically, as is the case for single solitons. Each type is stable in the sense that a given bound state exists in the same form inde.nitely. Single solitons can be perfectly stable for a given set of parameters. However, this does not mean that a bound state formed from them is either stationary or stable. Moreover, their relations can be highly complicated. Such is the life of dissipative solitons. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Soliton complexes in dissipative systems: Vibrating, shaking and mixed soliton pairs
2007
We show, numerically, that coupled soliton pairs in nonlinear dissipative systems modeled by the cubic-quintic complex Ginzburg-Landau equation can exist in various forms. They can be stationary, or they can pulsate periodically, quasiperiodically, or chaotically, as is the case for single solitons. In particular, we have found various types of vibrating and shaking soliton pairs. Each type is stable in the sense that a given bound state exists in the same form indefinitely. New solutions appear at special values of the equation parameters, thus bifurcating from stationary pairs. We also report the finding of mixed soliton pairs, formed by two different types of single solitons. We present …
Complexes and Molecules of Dissipative Solitons in Mode-Locked Lasers
2009
Pulse-pulse interaction is a major issue in the development of high-repetition rate fiber laser sources or soliton-based optical transmission lines. The design of a suitable level of nonlinear dissipation, through nonlinear filters or saturable absorbers for instance, is able to improve significantly the stability of multiple pulse operation. The concept of a dissipative soliton has become an important tool for the exploration and the analysis of the multiple pulse dynamics, with mode-locked lasers and regenerated transmission lines as important applications [1,2]. Above all, the study of dissipative solitons has become a fertile area of nonlinear science with multidisciplinary implications…
Dissipative Optical Breather Molecular Complexes
2020
We demonstrate different types of breathing soliton complexes in a mode-locked fibre laser: multi-breather molecules, and molecular complexes arising from the binding of two breather-pair molecules or a breather-pair molecule and a single breather.
Stationary and pulsating dissipative light bullets from a collective variable approach
2009
A collective variable approach is used to map domains of existence for (3+1) -dimensional spatiotemporal soliton solutions of a complex cubic-quintic Ginzburg-Landau equation. A rich variety of evolution behaviors, which include stationary and pulsating dissipative soliton dynamics, is revealed. Comparisons between the results obtained by the semianalytical approach of collective variables, and those obtained by a purely numerical approach show good agreement for a wide range of equation parameters. This also demonstrates the relevance of the semianalytical method for a systematic search of stability domains for spatiotemporal solitons, leading to a dramatic reduction of the computation tim…
Optical bullets and double bullet complexes in dissipative systems
2006
We show that optical light bullets can coexist with double bullet complexes in nonlinear dissipative systems. Coexistence occurs for a relatively large range of the system parameters, and is associated with either marginal stability or bistable existence of the two dissipative soliton species. In the case of marginal stability, spontaneous transformations of single bullets into double bullet complexes are observed. Among the bistable cases, we show how both clockwise and anticlockwise rotating double bullet complexes can be formed out of the phase-controlled interaction of two single bullets. The internal dynamics of pulsating double bullet complexes, with oscillations in both the spatial s…
Dissipative soliton in a laser cavity: A novel concept in action
2006
International audience; The recent concept of a dissipative optical soliton sheds new light for understanding the stability of optical pulses that are generated in passively mode-locked lasers. Considering in these lasers the multiple pulsing regime of operation, the dissipative soliton concept is able to explain the great diversity of interaction behaviours that have been observed experimentally. Among the most spectacular behaviours are the formation of "soliton molecules" and "elastic-type" collisions. The dissipative soliton also explains the existence of complex limit cycles of pulsations within single pulse operation.
Field-free molecular alignment of CO2 mixtures in presence of collisional relaxation
2008
The present work explores the extension of the concept of short-pulse-induced alignment to dissipative environments within quantum mechanical density matrix formalism (Liouville equation) from the weak to the strong field regime. This is illustrated within the example of the CO2 molecule in mixture with Ar and He, at room temperature, for which a steep decrease of the alignment is observed at moderate pressure because of the collisional relaxation. The field-free alignment is measured by a polarization technique where the degree of alignment is monitored in the time domain by measuring the resulting transient birefringence with a probe pulse Raman induced polarization spectroscopy (RIPS) Co…