Littérature scientifique sur le sujet « Equation de Lindblad »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les listes thématiques d’articles de revues, de livres, de thèses, de rapports de conférences et d’autres sources académiques sur le sujet « Equation de Lindblad ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Articles de revues sur le sujet "Equation de Lindblad"
1
Tarasov, Vasily E. « Quantum Maps with Memory from Generalized Lindblad Equation ». Entropy 23, no 5 (28 avril 2021) : 544. http://dx.doi.org/10.3390/e23050544.
Texte intégralRésumé :
In this paper, we proposed the exactly solvable model of non-Markovian dynamics of open quantum systems. This model describes open quantum systems with memory and periodic sequence of kicks by environment. To describe these systems, the Lindblad equation for quantum observable is generalized by taking into account power-law fading memory. Dynamics of open quantum systems with power-law memory are considered. The proposed generalized Lindblad equations describe non-Markovian quantum dynamics. The quantum dynamics with power-law memory are described by using integrations and differentiation of non-integer orders, as well as fractional calculus. An example of a quantum oscillator with linear friction and power-law memory is considered. In this paper, discrete-time quantum maps with memory, which are derived from generalized Lindblad equations without any approximations, are suggested. These maps exactly correspond to the generalized Lindblad equations, which are fractional differential equations with the Caputo derivatives of non-integer orders and periodic sequence of kicks that are represented by the Dirac delta-functions. The solution of these equations for coordinates and momenta are derived. The solutions of the generalized Lindblad equations for coordinate and momentum operators are obtained for open quantum systems with memory and kicks. Using these solutions, linear and nonlinear quantum discrete-time maps are derived.
2
Fagnola, Franco, et Carlos M. Mora. « Basic Properties of a Mean Field Laser Equation ». Open Systems & ; Information Dynamics 26, no 03 (septembre 2019) : 1950015. http://dx.doi.org/10.1142/s123016121950015x.
Texte intégralRésumé :
We study the nonlinear quantum master equation describing a laser under the mean field approximation. The quantum system is formed by a single mode optical cavity and two level atoms, which interact with reservoirs. Namely, we establish the existence and uniqueness of the regular solution to the nonlinear operator equation under consideration, as well as we get a probabilistic representation for this solution in terms of a mean field stochastic Schrödinger equation. To this end, we find a regular solution for the nonautonomous linear quantum master equation in Gorini–Kossakowski–Sudarshan–Lindblad form, and we prove the uniqueness of the solution to the nonautonomous linear adjoint quantum master equation in Gorini–Kossakowski–Sudarshan–Lindblad form. Moreover, we obtain rigorously the Maxwell–Bloch equations from the mean field laser equation.
3
ISAR, A., A. SANDULESCU, H. SCUTARU, E. STEFANESCU et W. SCHEID. « OPEN QUANTUM SYSTEMS ». International Journal of Modern Physics E 03, no 02 (juin 1994) : 635–714. http://dx.doi.org/10.1142/s0218301394000164.
Texte intégralRésumé :
The damping of the harmonic oscillator is studied in the framework of the Lindblad theory for open quantum systems. A generalization of the fundamental constraints on quantum mechanical diffusion coefficients which appear in the master equation for the damped quantum oscillator is presented; the Schrödinger, Heisenberg and Weyl-Wigner-Moyal representations of the Lindblad equation are given explicitly. On the basis of these representations it is shown that various master equations for the damped quantum oscillator used in the literature are particular cases of the Lindblad equation and that not all of these equations are satisfying the constraints on quantum mechanical diffusion coefficients. Analytical expressions for the first two moments of coordinate and momentum are obtained by using the characteristic function of the Lindblad master equation. The master equation is transformed into Fokker-Planck equations for quasiprobability distributions and a comparative study is made for the Glauber P representation, the antinormal ordering Q representation, and the Wigner W representation. The density matrix is represented via a generating function, which is obtained by solving a timedependent linear partial differential equation derived from the master equation. Illustrative examples for specific initial conditions of the density matrix are provided. The solution of the master equation in the Weyl-Wigner-Moyal representation is of Gaussian type if the initial form of the Wigner function is taken to be a Gaussian corresponding (for example) to a coherent wavefunction. The damped harmonic oscillator is applied for the description of the charge equilibration mode observed in deep inelastic reactions. For a system consisting of two harmonic oscillators the time dependence of expectation values, Wigner function and Weyl operator, are obtained and discussed. In addition models for the damping of the angular momentum are studied. Using this theory to the quantum tunneling through the nuclear barrier, besides Gamow’s transitions with energy conservation, additional transitions with energy loss are found. The tunneling spectrum is obtained as a function of the barrier characteristics. When this theory is used to the resonant atom-field interaction, new optical equations describing the coupling through the environment of the atomic observables are obtained. With these equations, some characteristics of the laser radiation absorption spectrum and optical bistability are described.
4
Pearle, Philip. « Simple derivation of the Lindblad equation ». European Journal of Physics 33, no 4 (27 avril 2012) : 805–22. http://dx.doi.org/10.1088/0143-0807/33/4/805.
Texte intégral
5
Kostyakov, I. V., V. V. Kuratov et N. A. Gromov. « Lie algebra contractions and the Lindblad equation ». Proceedings of the Komi Science Centre of the Ural Division of the Russian Academy of Sciences 6 (2021) : 36–41. http://dx.doi.org/10.19110/1994-5655-2021-6-36-41.
Texte intégralRésumé :
The dynamics of an open quantum system leads to decoherence, which is accompanied by limiting transitions in the Lie algebra of observables and appearance of abelian subalgebras. It is possible to set an inverse problem as well – by a given Lie algebra contraction to find the dynamics of an open quantum system given by the Lindblad equation. The paper proposes examples of finding the Lindblad equation by the known contractions of algebra su(3).
6
Karabanov, A. A. « Symmetry reductions of Lindblad equations – simple examples and applications ». Proceedings of the Komi Science Centre of the Ural Division of the Russian Academy of Sciences 6 (2021) : 49–52. http://dx.doi.org/10.19110/1994-5655-2021-6-49-52.
Texte intégralRésumé :
Open quantum dynamics in the Markovian approximation is described by the Lindblad master equation. The Lindbladian dynamics is closed in the Lie algebra Λ = su(n), i.e. it has su(n) symmetry. We say that the Lindblad equation admits a symmetry reduction if it has an invariant vector subspace Λ0 ⊂Λ with the Lie algebraic structure. Symmetry reductions restrict dynamics to smaller subspaces that additionally are Lie algebras. In these notes, trivial reductions relying onthe reducibility of the Hamiltonian and Lindblad operators are described. Examples of nontrivial reductions in the infinite temperature limit and the parity preserving Majorana reductions are presented. Applicationsto open spin dynamics are discussed.
7
FUJII, KAZUYUKI. « ALGEBRAIC STRUCTURE OF A MASTER EQUATION WITH GENERALIZED LINDBLAD FORM ». International Journal of Geometric Methods in Modern Physics 05, no 07 (novembre 2008) : 1033–40. http://dx.doi.org/10.1142/s0219887808003168.
Texte intégralRésumé :
The quantum damped harmonic oscillator is described by the master equation with usual Lindblad form. The equation has been solved completely by us in arXiv: 0710.2724 [quant-ph]. To construct the general solution a few facts of representation theory based on the Lie algebra su(1,1) were used. In this paper we treat a general model described by a master equation with generalized Lindblad form. Then we examine the algebraic structure related to some Lie algebras and construct the interesting approximate solution.
8
Vacchini, Bassano. « General structure of quantum collisional models ». International Journal of Quantum Information 12, no 02 (mars 2014) : 1461011. http://dx.doi.org/10.1142/s0219749914610115.
Texte intégralRésumé :
We point to the connection between a recently introduced class of non-Markovian master equations and the general structure of quantum collisional models. The basic construction relies on three basic ingredients: a collection of time dependent completely positive maps, a completely positive trace preserving transformation and a waiting time distribution characterizing a renewal process. The relationship between this construction and a Lindblad dynamics is clarified by expressing the solution of a Lindblad master equation in terms of demixtures over different stochastic trajectories for the statistical operator weighted by suitable probabilities on the trajectory space.
9
Binney, James. « Angle-action variables for orbits trapped at a Lindblad resonance ». Monthly Notices of the Royal Astronomical Society 495, no 1 (19 mai 2020) : 886–94. http://dx.doi.org/10.1093/mnras/staa092.
Texte intégralRésumé :
ABSTRACT The conventional approach to orbit trapping at Lindblad resonances via a pendulum equation fails when the parent of the trapped orbits is too circular. The problem is explained and resolved in the context of the Torus Mapper and a realistic Galaxy model. Tori are computed for orbits trapped at both the inner and outer Lindblad resonances of our Galaxy. At the outer Lindblad resonance, orbits are quasi-periodic and can be accurately fitted by torus mapping. At the inner Lindblad resonance, orbits are significantly chaotic although far from ergodic, and each orbit explores a small range of tori obtained by torus mapping.
10
Ou, Congjie, Yuho Yokoi et Sumiyoshi Abe. « Spin Isoenergetic Process and the Lindblad Equation ». Entropy 21, no 5 (17 mai 2019) : 503. http://dx.doi.org/10.3390/e21050503.
Texte intégralRésumé :
A general comment is made on the existence of various baths in quantum thermodynamics, and a brief explanation is presented about the concept of weak invariants. Then, the isoenergetic process is studied for a spin in a magnetic field that slowly varies in time. In the Markovian approximation, the corresponding Lindbladian operators are constructed without recourse to detailed information about the coupling of the subsystem with the environment called the energy bath. The entropy production rate under the resulting Lindblad equation is shown to be positive. The leading-order expressions of the power output and work done along the isoenergetic process are obtained.
Thèses sur le sujet "Equation de Lindblad"
1
Debierre, Vincent. « La fonction d'onde du photon en principe et en pratique ». Thesis, Ecole centrale de Marseille, 2015. http://www.theses.fr/2015ECDM0004/document.
Texte intégralRésumé :
Pendant ces trois ans, nous nous sommes intéressés à quelques sujets choisis en optique et en électrodynamique quantiques. Le fil rouge de nos interrogations est la fonction d’onde du photon. Les expériences d’optique et d’électrodynamique quantique peuvent-elles être décrites de manière simple, dans l’espace des positions, à l’aide d’une fonction d’onde décrivant le ou les photon(s) impliqués dans l’expérience ? Ce n’est pas entièrement évident :la description usuelle des photons se fait dans l’espace réciproque des vecteurs d’onde. Mais ces expériences gagnent à être décrites par la mécanique ondulatoire en représentation position, comme cela est fait dans les manuels de mécanique quantique pour des situations impliquant des particules massives. De surcroît, une expérience récente[1] a conduit à l’observation de trajectoires de photons uniques à travers un interféromètre à deux fentes d’Young.Pour essayer de décrire formellement ces trajectoires, il est naturel de formuler une mécanique ondulatoire pour les photons. Nous avons donc examiné en détail la construction formelle de la fonction d’onde du photon, un objet qui est resté peu étudié jusqu’aux années 1990. Nous avons également étudié les propriétés de la fonction d’onde du photon en présence de sources, et considéré pour ce faire divers systèmes quantiques ouverts (en interaction). Nous avons vu qu’il existe, en principe, une infinité de possibilités pour le choix de la fonction d’onde du photon.Nous avons mis en évidence un certain nombre de critères sur la base desquels il apparaît que seuls trois choix parmi tous ceux possibles sont intéressants, l’un d’entre eux ramenant à un objet introduit par Glauber [2] pour étudier la détection de la lumière et les corrélations du champ électromagnétique. Nous avons également vu qu’en l’absence de sources l’équation quantique de propagation des photons est formellement identique aux équations de Maxwell.À bas nombre de photons, le formalisme de la fonction d’onde peut se révéler très pratique. Nous avons adapté l’approche aux systèmes en interaction, en nous intéressant dans un premier temps à l’électrodynamique quantique1en cavité [3], en particulier aux expériences réalisées par le groupe de Serge Haroche [4]. Nous avons proposé un modèle simple pour la description des photons dans les cavités d’électrodynamique. À l’aide de ce modèle, et de la fonction d’onde du photon, nous avons étudié la propagation des photons s’échappant de la cavité. Nous avons également construit l’équation maîtresse de Lindblad sans introduire de sauts quantiques non unitaires (voir également [5]). Nous nous sommes enfin intéressés à la question de l’évolution spatiotemporelle d’un photon émis lors d’une désexcitation d’un électron atomique. Après avoir étudié soigneusement la dynamique de la désexcitation de l’électron, notamment aux temps très courts [6, 7], nous nous sommes attachés à décrire, aussi rigoureusement que possible, le champ électromagnétique émis. Celui-ci, de manière surprenante, n’évolue pas causalement. Si cela n’est pas entièrement inattendu au vu du théorème de Hegerfeldt, qui stipule [8] que la causalité est exclue pour les systèmes décrits par un Hamiltonien dont le spectre est borné inférieurement, nous avons identifié [9] deux autres sources de non-causalité, l’une, prédite qualitativement par Shirokov [10], et l’autre, entièrement nouvelle à notre connaissance, et dont la compréhension reste à affinerDuring these three years we focused on several topics in quantum otpics and quantum electrodynamics. A central theme in our investigations is that of the photon wave function. Can quantum optics and quantum electrodynamics experiments be described simply, in position space, with the help of a wave function describing the photon(s) featured in the experiment ? The answer to that question is not quite obvious: the usual description of photons takes place in the reciprocal space of wave vectors. But these experiments call for a wave mechanical description in the position representation, as is done in quantum mechanics textbooks in situations featuring massive particles. Moreover, in a recent experiment [1], single photon trajectories through a Young two-slit setup have been observed. In order to try and describe these trajectories formally, it is natural to build a wave mechanical formalism for photons. We therefore studied in detail the formal construction of the photon wave function, an object which was little studied until the 1990s. We also studied the properties of the photon wave function in the presence of sources.To do that, we considered several open (interacting) quantum systems. We saw that there exists in principle an infinite number of possibilities when defining the photon wave function. We emphasised several criteria on the basis of which it appears that only three choices for the wave function are interesting. One of them coincides with an object introduced and used by Glauber [2] to study light detection andthe correlations of the electromagnetic field in the quantum regime. We also saw that, in the absence of sources, the propagation equation for a single photon is formally equivalent to Maxwell’s equations. At low photon numbers, the wave function formalism can be very useful. We adapted it to interacting systems,first, to cavity quantum electrodynamics (QED) [3], in particular to the experiments carried out by Serge Haroche’s group [4]. We proposed a simple model to describe photons in QED cavities. With this model, and with the helpof the photon wave function, we studied the propagation of photons escaping a cavity. We also constructed the Lindblad master equation without introducing nonunitary quantum jumps (also see [5]). We finally investigated the spacetime evolution of a photon which is emitted during the decay of an atomic electron. After having carefully studied the dynamics of the electronic decay, especially at very short times [6, 7], we set out to describe the emitted electromagnetic field as rigorously as possible. This emitted field, surprisingly, does not evolve causally. Though this is not entirely unexpected in view of Hegerfeldt’s theorem, which states [8] that causality is impossible for quantum systems which are described by a Hamiltonian with a spectrum which is bounded by below, we identified [9] two other sources of non causality. One of them was predicted qualitatively by Shirokov [10], while the other one, which is completely new as far as we can tell, is still to be better understood
2
Lindblad, Petersen Oliver [Verfasser], et Christian [Akademischer Betreuer] Bär. « The Cauchy problem for the linearised Einstein equation and the Goursat problem for wave equations / Oliver Lindblad Petersen ; Betreuer : Christian Bär ». Potsdam : Universität Potsdam, 2018. http://d-nb.info/1219149489/34.
Texte intégral
3
Zuo, Xingdong. « Derivation of the Lindblad Equation for Open Quantum Systems and Its Application to Mathematical Modeling of the Process of Decision Making ». Thesis, Linnéuniversitetet, Institutionen för matematik (MA), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-38711.
Texte intégralRésumé :
In the theory of open quantum systems, a quantum Markovian master equation, the Lindblad equation, reveals the most general form for the generators of a quantum dynamical semigroup. In this thesis, we present the derivation of the Lindblad equation and several examples of Lindblad equations with their analytic and numerical solutions. The graphs of the numerical solutions illuminate the dynamics and the stabilization as time increases. The corresponding von Neumann entropies are also presented as graphs. Moreover, to illustrate the difference between the dynamics of open and isolated systems, we prove two theorems about the conditions for stabilization of the solutions of the von Neumann equation which describes the dynamics of the density matrix of open quantum systems. It shows that the von Neumann equation is not satisfied for modelling dynamics in the cognitive contextin general. Instead, we use the Lindblad equation to model the mental dynamics of the players in the game of the 2-player prisoner’s dilemma to explain the irrational behaviors of the players. The stabilizing solution will lead the mental dynamics to an equilibrium state, which is regarded as the termination of the comparison process for a decision maker. The resulting pure strategy is selected probabilistically by performing a quantum measurement. We also discuss two important concepts, quantum decoherence and quantum Darwinism. Finally, we mention a classical Neural Network Master Equation introduced by Cowan and plan our further works on an analogous version for the quantum neural network by using the Lindblad equation.
4
Pinna, Lorenzo. « On the controllability of the quantum dynamics of closed and open systems ». Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLX017/document.
Texte intégralRésumé :
On etudie la contrôlabilité des systèmes quantiques dans deux contextes différents: le cadre standard fermé, dans lequel un système quantique est considéré comme isolé et le problème de contrôle est formulé sur l'équation de Schrödinger; le cadre ouvert qui décrit un système quantique en interaction avec un plus grand, dont seuls les paramètres qualitatifs sont connus, au moyen de l'équation de Lindblad sur les états.Dans le contexte des systèmes fermés on se focalise sur la classe intéressante des systèmes spin-boson, qui décrivent l'interaction entre un système quantique à deux niveaux et un nombre fini de modes distingués d'un champ bosonique. On considère deux exemples prototypiques, le modèle de Rabi et le modèle de Jaynes-Cummings qui sont encore très populaires dans plusieurs domaines de la physique quantique. Notamment, dans le contexte de la Cavity Quantum Electro Dynamics (C-QED), ils fournissent une description précise de la dynamique d'un atome à deux niveaux dans une cavité micro-onde en résonance, comme dans les expériences récentes de S. Haroche. Nous étudions les propriétés de contrôlabilité de ces modèles avec deux types différents d'opérateurs de contrôle agissant sur la partie bosonique, correspondant respectivement – dans l'application à la C-QED – à un champ électrique et magnétique externe. On passe en revue quelques résultats récents et prouvons la contrôlabilité approximative du modèle de Jaynes-Cummings avec ces contrôles. Ce résultat est basé sur une analyse spectrale exploitant les non-résonances du spectre. En ce qui concerne la relation entre l'Hamiltonien de Rabi et Jaynes-Cummings nous traitons dans un cadre rigoureux l'approximation appelée d'onde tournante. On formule le problème comme une limite adiabatique dans lequel la fréquence de detuning et le paramètre de force d'interaction tombent à zero, ce cas est connu sous le nom de régime de weak-coupling. On prouve que, sous certaines hypothèses sur le rapport entre le detuning et le couplage, la dynamique de Jaynes-Cumming et Rabi montrent le même comportement, plus précisément les opérateurs d'évolution qu'ils génèrent sont proches à la norme.Dans le cadre des systèmes quantiques ouverts nous étudions la contrôlabilité de l'équation de Lindblad. Nous considérons un contrôle agissant adiabatiquement sur la partie interne du système, que nous voyons comme un degré de liberté qui peut être utilisé pour contraster l'action de l'environnement. L'action adiabatique du contrôle est choisie pour produire une transition robuste. On prouve, dans le cas prototype d'un système à deux niveaux, que le système approche un ensemble de points d'équilibre déterminés par l'environnement, plus précisément les paramètres qui spécifient l'opérateur de Lindblad. Sur cet ensemble, le système peut être piloté adiabatiquement en choisissant un contrôle approprié. L'analyse est fondée sur l'application de méthodes de perturbation géométrique singulièreWe investigate the controllability of quantum systems in two differentsettings: the standard 'closed' setting, in which a quantum system is seen as isolated, the control problem is formulated on the Schroedinger equation; the open setting that describes a quantum system in interaction with a larger one, of which just qualitative parameters are known, by means of the Lindblad equation on states.In the context of closed systems we focus our attention to an interesting class ofmodels, namely the spin-boson models. The latter describe the interaction between a 2-level quantum system and finitely many distinguished modes of a bosonic field. We discuss two prototypical examples, the Rabi model and the Jaynes-Cummings model, which despite their age are still very popular in several fields of quantum physics. Notably, in the context of cavity Quantum Electro Dynamics (C-QED) they provide an approximate yet accurate description of the dynamics of a 2-level atom in a resonant microwave cavity, as in recent experiments of S. Haroche. We investigate the controllability properties of these models, analyzing two different types of control operators acting on the bosonic part, corresponding -in the application to cavity QED- to an external electric and magnetic field, respectively. We review some recent results and prove the approximate controllability of the Jaynes-Cummings model with these controls. This result is based on a spectral analysis exploiting the non-resonances of the spectrum. As far as the relation between the Rabi andthe Jaynes-Cummings Hamiltonians concerns, we treat the so called rotating waveapproximation in a rigorous framework. We formulate the problem as an adiabaticlimit in which the detuning frequency and the interaction strength parameter goes to zero, known as the weak-coupling regime. We prove that, under certain hypothesis on the ratio between the detuning and the coupling, the Jaynes-Cumming and the Rabi dynamics exhibit the same behaviour, more precisely the evolution operators they generate are close in norm.In the framework of open quantum systems we investigate the controllability ofthe Lindblad equation. We consider a control acting adiabatically on the internal part of the system, which we see as a degree of freedom that can be used to contrast the action of the environment. The adiabatic action of the control is chosen to produce a robust transition. We prove, in the prototype case of a two-level system, that the system approach a set of equilibrium points determined by the environment, i.e. the parameters that specify the Lindblad operator. On that set the system can be adiabatically steered choosing a suitable control. The analysis is based on the application of geometrical singular perturbation methods
5
Gozzi, Riccardo. « Open dynamics of su(3) quantum systems ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/12395/.
Texte intégralRésumé :
Questo lavoro di tesi nasce con lo scopo di fornire una inquadratura generale del campo di studi relativo ad i sistemi quantistici aperti.
Esattamente come avviene nel caso della termodinamica, questo tipo di approfondimento vuole tenere conto delle interazioni che un qualunque sistema quantistico può sviluppare con l'ambiente esterno.
La prima parte del lavoro intende introdurre il lettore all'argomento; in queste prime sezioni si trattano anche alcuni argomenti più concettuali di rilevanza prettamente fisica, come ad esempio il fenomeno dell'entanglement o del quantum eraser.
La seconda parte presenta un approccio geometrico, allo scopo di chiarire come vengono a modificarsi in questo nuovo contesto le strutture geometriche entro cui si sviluppa il sistema quantistico interagente, intendendo con ciò sia le orbite unitarie, sia gli spazi formati dagli stati puri e dagli stati misti.
Infine, la parte finale della tesi sviluppa questi argomenti in due circostanze applicative, relative all'insieme delle matrici densità rispettivamente di dimensione due e tre. Nello specifico, queste due trattazioni analizzano specialmente le problematiche relative all'evoluzione temporale aperta , ossia quel tipo di evoluzione osservabile esclusivamente in caso di interazione del sistema quantistico con un ambiente esterno, e che per questo si discosta dalle usuali evoluzioni unitarie descrivendo invece una traiettoria che permette il passaggio dall'una all'altra di queste orbite.
6
Brasil, Carlos Alexandre. « Descrição de medidas em sistemas de 2 níveis pela equação de Lindblad com inclusão de ambiente ». Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-12032012-080819/.
Texte intégralRésumé :
O objetivo deste trabalho é explorar um modelo para medidas quânticas de duração finita baseado na equação de Lindblad, com a análise de um sistema de 2 níveis acoplado a um reservatório térmico que ocasiona decoerência. A interação entre o sistema e o dispositivo de medida é markoviana, justificando o uso da equação de Lindblad para obter a dinâmica do processo de medida. Para analisar a influência do ambiente/reservatório térmico não-markoviano, cuja definição não inclui o aparato de medida, foi utilizada a abordagem de Redfield para a interação entre o sistema e o ambiente. Na teoria híbrida aqui exposta, para efetuar o traço parcial dos graus de liberdade do ambiente foi desenvolvido um método analítico baseado na álgebra de super-operadores e no uso dos super-operadores de Nakajima-Zwanzig. Foi verificado que medidas de duração finita sobre o sistema aberto de 2 níveis podem proteger o estado inicial dos efeitos do ambiente, desde que o observável medido não comute com a interação. Quando o observável medido comuta com a interação sistema-ambiente, a medida de duração finita acelera a decoerência induzida pelo ambiente. A validade das previsões analíticas foi testada comparando os resultados com uma abordagem numérica exata. Quando o acoplamento entre o sistema e o aparato de medida excede a faixa de validade da aproximação analítica, o estado inicial ainda é protegido pela medida de duração finita, como indicam os cálculos numéricos exatos.The aim of this work is to explore a model for finite-time measurement based on the Lindblad equation, with analysis of a system consisting of a 2-level system coupled to a thermal reservoir. We assume a Markovian measuring device and, therefore, use a Lindbladian description for the measurement dynamics. For studying the case of noise produced by a non-Markovian environment, whose definition does not include the measuring apparatus, we use the Redfield approach to the interaction between system and environment. In the present hybrid theory, to trace out the environmental degrees of freedom, we introduce an analytic method based on superoperator algebra and Nakajima-Zwanzig superoperators. We show that measurements of finite duration performed on an open two-state system can protect the initial state from a phase-noisy environment, provided the measured observable does not commute with the perturbing interaction. When the measured observable commutes with the environmental interaction, the finite-duration measurement accelerates the rate of decoherence induced by the phase noise. We have tested the validity of the analytical predictions against an exact numerical approach. When the coupling between the system and the measuring apparatus increases beyond the range of validity of the analytical approximation, the initial state is still protected by the finite-time measurement, according with the exact numerical calculations.
7
Bystrik, Y. « Driven anharmonic oscillator : classical and quantum analysis ». Thesis, Sumy State University, 2016. http://essuir.sumdu.edu.ua/handle/123456789/46814.
Texte intégralRésumé :
The existence of a perfectly isolated quantum system is impossible. In
reality, no quantum system is completely isolated from its surroundings, so
every quantum system is open to some extent. The dynamics of any open
quantum system is described by Lindblad equation [1].
8
Ribeiro, Wellington Luiz. « Evolution of a 1D bipartite fermionic chain under in?uence of a phenomenological dephasing ». reponame:Repositório Institucional da UFABC, 2018.
Trouver le texte intégralRésumé :
Orientador: Prof. Dr. Gabriel Teixeira LandiDissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Física, Santo André, 2018.
Em sistemas microscópicos, grandezas como calor e trabalho devem ser tratadas como variáveis aleatórias. Neste trabalho foram estudados os fluxos de calor e de partículas entre dois sistemas unidimensionais fermiônicos A eB, inicialmente preparados separadamente em equilíbrio térmico com reservatórios de calor e partículas preparados a diferentes temperaturas e diferentes potenciais químicos. Calculando a evolução da matriz densidade, foram analisadas as implicações da presença de um ruído de dephasing no sistema, tais como a termalização, a produção de entropia e a evolução da informação mútua como uma forma de analisar a correlação entre os sistemas. Além disso, foi estudado também uma forma do teorema de flutuação do calor no caso onde há fluxo de partículas.
In microscopic systems, heat and work must be treated as random variables. In this work I studied the fluxes of heat and particles between two unidimentional fermionic systems A and B, initially prepared in thermal equilibrium with a reservoir of particles and heat, kept at diferent temperatures and chemical potentials. Computing the evolution of the density matrix, the implications of the presence of a dephasing noise in the system were analyzed, such as thermalization, entropy production and the evolution of mutual information as a way to analyze the correlation between the systems. Moreover, a shape for fluctuation theorems of the heat in the case where there is also a ?ux of particles and its validity was also studied.
9
Ermakova, Natalia. « Signatures of topological phases in an open Kitaev chain ». Thesis, KTH, Fysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-300177.
Texte intégralRésumé :
Some physical systems exhibit topological properties in the form of topological invariants— features of the system that remain constant unless the system undergoessignificant changes i.e. changes that require closing the energy gap of the Hamiltonian.This work studies one example of a system with topological properties — a Kitaevchain. Here, this model is studied when it is coupled to an environment. We studythe effect of the coupling on the topology of the system and attempt to find signaturesof topological phases in the dynamics of the system. By using the Lindblad equationdefined in the formalism of third quantization, we study the time evolution of thesystem numerically by using the Euler method. We find that the dynamics of theentanglement spectrum of half of the chain is different in the topological and trivialphases: if the system undergoes a quench from trivial to topological phase, the entanglementspectrum exhibits crossings as the system evolves in time. We also studythe topological phases when disorder is added to the system. We test the stabilityof the topological phases of the system against disorder and find that the topologicalphases are not affected by a weak disorder. Moreover, by studying the statistics of theminimum entanglement spectrum gap, we find that, in general, a stronger disordermakes the crossings less likely to appear in the topological phase and more likely toappear in the trivial phase.Det finns fysiska system som visar topologiska egenskaper i form av topologiska invarianter,som ändras inte så länge systemet genomgår ändringar som inte stängerHamiltonianens energigap. I det här arbetet undersöker vi ett exempel av ett systemmed topologiska egenskaper — en Kitaev kedja. Denna modell är studerat närden är kopplad till en omgivning. Vi undersöker kopplingens påverkan på systemetstopologi och vi försöker hitta tecken på topologiska faser i systemets dynamik. Vianvänder Lindblads ekvation definierat i tredje kvantiserings formalism för att studerasystemets tidsutveckling numeriskt, genom att använda Eulers metod. Vi upptäckeratt det finns skillnader i tidsutveckling av kvantsammanflätningsspektrumav häften av kedjan som beror på systems topologiska fas. Om systemet genomgåren kvantsläckning från den triviala till den topologiska fasen, kommer det finnas korsningari kvantsammanflätningensspektrum som uppstår under dess tidsutveckling.Dessutom studerar vi de topologiska faserna när det finns oordning i systemet. Viundersöker topologiska fasernas stabilitet mot oordning och upptäcker att en svagoordning påverkar inte de topologika faserna. Dessutom, genom att studera den minstakvantsammanflätningsspektrumsgap upptäcker vi att en starkare oordning ledertill kvantsammanflätningsspektrumskorsningar att vara mindre sannolika i den topologiskafasen och mer sannolika i den triviala fasen.
10
Schlesinger, Martin. « Quantum Dissipative Dynamics and Decoherence of Dimers on Helium Droplets ». Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-82729.
Texte intégralRésumé :
In this thesis, quantum dynamical simulations are performed in order to describe the vibrational motion of diatomic molecules in a highly quantum environment, so-called helium droplets. We aim to reproduce and explain experimental findings which were obtained from dimers on helium droplets. Nanometer-sized helium droplets contain several thousands of 4-He atoms. They serve as a host for embedded atoms or molecules and provide an ultracold “refrigerator” for them. Spectroscopy of molecules in or on these droplets reveals information on both the molecule and the helium environment. The droplets are known to be in the superfluid He II phase. Superfluidity in nanoscale systems is a steadily growing field of research. Spectra obtained from full quantum simulations for the unperturbed dimer show deviations from measurements with dimers on helium droplets. These deviations result from the influence of the helium environment on the dimer dynamics. In this work, a well-established quantum optical master equation is used in order to describe the dimer dynamics effectively. The master equation allows to describe damping fully quantum mechanically. By employing that equation in the quantum dynamical simulation, one can study the role of dissipation and decoherence in dimers on helium droplets. The effective description allows to explain experiments with Rb-2 dimers on helium droplets. Here, we identify vibrational damping and associated decoherence as the main explanation for the experimental results. The relation between decoherence and dissipation in Morse-like systems at zero temperature is studied in more detail. The dissipative model is also used to investigate experiments with K-2 dimers on helium droplets. However, by comparing numerical simulations with experimental data, one finds that further mechanisms are active. Here, a good agreement is obtained through accounting for rapid desorption of dimers. We find that decoherence occurs in the electronic manifold of the molecule. Finally, we are able to examine whether superfluidity of the host does play a role in these experimentsIn dieser Dissertation werden quantendynamische Simulationen durchgeführt, um die Schwingungsbewegung zweiatomiger Moleküle in einer hochgradig quantenmechanischen Umgebung, sogenannten Heliumtröpfchen, zu beschreiben. Unser Ziel ist es, experimentelle Befunde zu reproduzieren und zu erklären, die von Dimeren auf Heliumtröpfchen erhalten wurden. Nanometergroße Heliumtröpfchen enthalten einige tausend 4-He Atome. Sie dienen als Wirt für eingebettete Atome oder Moleküle und stellen für dieseeinen ultrakalten „Kühlschrank“ bereit. Durch Spektroskopie mit Molekülen in oder auf diesen Tröpfchen erhält man Informationen sowohl über das Molekül selbst als auch über die Heliumumgebung. Man weiß, dass sich die Tröpfchen in der suprafluiden He II Phase befinden. Suprafluidität in Nanosystemen ist ein stetig wachsendes Forschungsgebiet. Spektren, die für das ungestörte Dimer durch voll quantenmechanische Simulationen erhalten werden, weichen von Messungen mit Dimeren auf Heliumtröpfchen ab. Diese Abweichungen lassen sich auf den Einfluss der Heliumumgebung auf die Dynamik des Dimers zurückführen. In dieser Arbeit wird eine etablierte quantenoptische Mastergleichung verwendet, um die Dynamik des Dimers effektiv zu beschreiben. Die Mastergleichung erlaubt es, Dämpfung voll quantenmechanisch zu beschreiben. Durch Verwendung dieser Gleichung in der Quantendynamik-Simulation lässt sich die Rolle von Dissipation und Dekohärenz in Dimeren auf Heliumtröpfchen untersuchen. Die effektive Beschreibung erlaubt es, Experimente mit Rb-2 Dimeren zu erklären. In diesen Untersuchungen wird Dissipation und die damit verbundene Dekohärenz im Schwingungsfreiheitsgrad als maßgebliche Erklärung für die experimentellen Resultate identifiziert. Die Beziehung zwischen Dekohärenz und Dissipation in Morse-artigen Systemen bei Temperatur Null wird genauer untersucht. Das Dissipationsmodell wird auch verwendet, um Experimente mit K-2 Dimeren auf Heliumtröpfchen zu untersuchen. Wie sich beim Vergleich von numerischen Simulationen mit experimentellen Daten allerdings herausstellt, treten weitere Mechanismen auf. Eine gute Übereinstimmung wird erzielt, wenn man eine schnelle Desorption der Dimere berücksichtigt. Wir stellen fest, dass ein Dekohärenzprozess im elektronischen Freiheitsgrad des Moleküls auftritt. Schlussendlich sind wir in der Lage herauszufinden, ob Suprafluidität des Wirts in diesen Experimenten eine Rolle spielt
Livres sur le sujet "Equation de Lindblad"
1
Kavokin, Alexey V., Jeremy J. Baumberg, Guillaume Malpuech et Fabrice P. Laussy. Quantum description of light–matter coupling. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198782995.003.0005.
Texte intégralRésumé :
In this chapter we study with the tools developed in Chapter 3 the basic models that are the foundations of light–matter interaction. We start with Rabi dynamics, then consider the optical Bloch equations that add phenomenologically the lifetime of the populations. As decay and pumping are often important, we cover the Lindblad form, a correct, simple and powerful way to describe various dissipation mechanisms. Then we go to a full quantum picture, quantizing also the optical field. We first investigate the simpler coupling of bosons and then culminate with the Jaynes–Cummings model and its solution to the quantum interaction of a two-level system with a cavity mode. Finally, we investigate a broader family of models where the material excitation operators differ from the ideal limits of a Bose and a Fermi field.
Chapitres de livres sur le sujet "Equation de Lindblad"
1
Haba, Zbigniew. « Lindblad equation and stochastic Schrödinger equation ». Dans Feynman Integral and Random Dynamics in Quantum Physics, 185–249. Dordrecht : Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4716-3_12.
Texte intégral
2
Soto-Eguibar, Francisco, Braulio Misael Villegas-Martínez et Héctor Manuel Moya-Cessa. « The Matrix Perturbation Method for the Lindblad Master Equation ». Dans The Matrix Perturbation Method in Quantum Mechanics, 137–55. Cham : Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-48546-6_6.
Texte intégral
3
Chattah, A. Karina, et Manuel O. Cáceres. « Computing the quantum Boltzmann equation from a Kossakowski-Lindblad generator ». Dans Nonlinear Phenomena and Complex Systems, 183–95. Dordrecht : Springer Netherlands, 2004. http://dx.doi.org/10.1007/978-1-4020-2149-7_11.
Texte intégral
4
Bertlmann, Reinhold A., et Nicolai Friis. « Open Quantum Systems, Decoherence, Atom-Field Coupling ». Dans Modern Quantum Theory, 726–57. Oxford University PressOxford, 2023. http://dx.doi.org/10.1093/oso/9780199683338.003.0022.
Texte intégralRésumé :
Abstract Chapter 22 investigates the dynamics of open quantum systems that interact with their environment. We discuss the time-evolution of the joint system in terms of a time-ordered exponential of an integral over the Hamiltonian and determine a similar formulation for a Liouvillian super-operator. Based on these ideas we develop the notion of dynamical maps and apply the Born-Markov approximation to arrive at a dynamical semi-group and general Markovian master equations. We then turn to a specific example of such an equation of motion for the density operator: the Gorini-Kossakowski-Lindblad-Sudarshan (GKLS) equation which captures both dissipative dynamics and decoherence using Lindblad operators. We employ the GKLS equation to model the absorption, and spontaneous as well as stimulated emission of radiation by a two-level atom. We then discuss the Jaynes-Cummings model that describes the interaction of such an atom with a single mode of the electromagnetic field in a cavity
5
Eichler, Alexander, et Oded Zilberberg. « From Closed to Open Quantum Systems ». Dans Classical and Quantum Parametric Phenomena, 132–42. Oxford University PressOxford, 2023. http://dx.doi.org/10.1093/oso/9780192862709.003.0010.
Texte intégralRésumé :
Abstract In this chapter, we generalize our treatment of quantum systems by allowing them to be coupled to an environment at a finite temperature, similar to what we discussed for classical systems in chapter 4. The time evolution of many open quantum system can be calculated using the Lindblad master equation. We study various effects of the thermal environment on the quantum harmonic oscillator, and then continue to include driving by an external force
Actes de conférences sur le sujet "Equation de Lindblad"
1
Riesch, Michael, Alek Pikl et Christian Jirauschek. « Completely Positive Trace Preserving Methods for the Lindblad Equation ». Dans 2020 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD). IEEE, 2020. http://dx.doi.org/10.1109/nusod49422.2020.9217670.
Texte intégral
2
Ribeiro, P., et V. R. Vieira. « NON-MARKOVIAN EFFECTS IN THE LINDBLAD MASTER EQUATION APPROACH TO ELECTRONIC TRANSPORT ». Dans 11th International School on Theoretical Physics. WORLD SCIENTIFIC, 2015. http://dx.doi.org/10.1142/9789814740371_0005.
Texte intégral
3
Anastopoulos, C., S. Shresta et B. L. Hu. « Quantum Entanglement under Non-Markovian Dynamics of Two Qubits Interacting with a Common Electromagnetic Field* ». Dans Workshop on Entanglement and Quantum Decoherence. Washington, D.C. : Optica Publishing Group, 2008. http://dx.doi.org/10.1364/weqd.2008.eoqs2.
Texte intégralRésumé :
We study the non-equilibrium dynamics of a pair of qubits made of two-level atoms separated in space with distance r and interacting with one common electromagnetic field but not directly with each other. Our calculation makes a weak coupling assumption, but no Born or Markov approximation. We derived a non-Markovian master equation for the evolution of the reduced density matrix of the two-qubit system after integrating out the electromagnetic field modes. It contains a Markovian part with a Lindblad type operator and a nonMarkovian contribution, the physics of which is the main focus of this study. We use the concurrence function as a measure of quantum entanglement between the two qubits. Two classes of states are studied in detail: Class A is a one parameter family of states which are the superposition of the highest energy |I〉 ≡ |11〉 and lowest energy |O〉 ≡ |00〉 states, υiz, |A〉≡p|I〉+(1−p)|O〉, with 0 ≤ p ≤ 1; and Class B states |B〉 are linear combinations of the symmetric |+〉=12(|01〉+|10〉) and the antisymmetric |−〉=12(|01〉−|10〉) Bell states.
4
Azouit, R., A. Sarlette et P. Rouchon. « Adiabatic elimination for open quantum systems with effective Lindblad master equations ». Dans 2016 IEEE 55th Conference on Decision and Control (CDC). IEEE, 2016. http://dx.doi.org/10.1109/cdc.2016.7798963.
Texte intégral
5
Rouchon, Pierre, et Alain Sarlette. « Contraction and stability analysis of steady-states for open quantum systems described by Lindblad differential equations ». Dans 2013 IEEE 52nd Annual Conference on Decision and Control (CDC). IEEE, 2013. http://dx.doi.org/10.1109/cdc.2013.6760928.
Texte intégralRapports d'organisations sur le sujet "Equation de Lindblad"
1
Spahn, G. Parallel-in-Time Simulation of Lindblad's Equation. Office of Scientific and Technical Information (OSTI), août 2020. http://dx.doi.org/10.2172/1647923.
Texte intégral