Tesis sobre el tema "Out-of-equilibrium quantum systems"
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Kasztelan, Christian. "Strongly Interacting Quantum Systems out of Equilibrium". Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-124827.
Texto completoGAMBETTA, FILIPPO MARIA. "Out-of-equilibrium dynamics of one-dimensional integrable quantum systems". Doctoral thesis, Università degli studi di Genova, 2018. http://hdl.handle.net/11567/930218.
Texto completoGoihl, Marcel [Verfasser]. "Emergence of Thermodynamics For Quantum Systems Out Of Equilibrium / Marcel Goihl". Berlin : Freie Universität Berlin, 2020. http://d-nb.info/1203129017/34.
Texto completoFriesdorf, Mathis [Verfasser]. "Closed quantum many-body systems out of equilibrium : A quantum information perspective / Mathis Friesdorf". Berlin : Freie Universität Berlin, 2016. http://d-nb.info/1099282829/34.
Texto completoBuchhold, Michael. "Thermalization and Out-of-Equilibrium Dynamics in Open Quantum Many-Body Systems". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-181786.
Texto completoHenriet, Loïc. "Non-equilibrium dynamics of many body quantum systems". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX036/document.
Texto completoThis thesis deals with the study of dynamical properties of out-of-equilibrium quantum systems. We introduce in particular a general class of Spin-Boson models, which describe for example light-matter interaction or dissipative phenomena. We contribute to the development of a stochastic approach to describe the spin dynamics in these models. In this context, the effect of the bosonic environment is encapsulated into additional stochastic degrees of freedom whose time-correlations are determined by spectral properties of the bosonic environment. We use this approach to study many-body phenomena such as the dissipative quantum phase transition induced by an ohmic bosonic environment. Synchronization phenomena as well as dissipative topological transitions are identified. We also progress in the study of arrays of interacting light-matter systems. These theoretical developments follow recent experimental achievements, which could ensure a quantitative study of these phenomena. This notably includes ultra-cold atoms, trapped ions and cavity and circuit electrodynamics setups. We also investigate hybrid systems comprising electronic quantum dots coupled to electromagnetic resonators, which enable us to provide a spectroscopic analysis of many-body phenomena linked to the Kondo effect. We also introducethermoelectric applications in these devices
Cevolani, Lorenzo. "Out-Of-Equilibrium Dynamics and Locality in Long-Range Many-Body Quantum Systems". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLO011/document.
Texto completoIn this thesis we present our results on the propagation of correlations in long-range interacting quantum systems. The dynamics of local observables in these systems cannot be described with the standard methods used in equilibrium statistical physics and completely new methods have to be developed. Several bounds on the time evolution of correlations have been derived for these systems. However the propagation found in experimental and numerical results is completely different and several regimes are present depending on the long-range character of the interactions. Here we present analytical expressions to describe the time evolution of generic observables in systems where the Hamiltonian takes a quadratic form with long- and short-range interactions. These expressions describe the spreading of local observables as the spreading of the fundamental excitations of the system. We apply these expressions to a spin model finding three different propagation regimes. They can be described qualitatively et quantitatively by the divergences in the energy spectrum. The most important result is that the propagation is at most ballistic, but it can be also significantly slower, where the general bounds predict a propagation faster than ballistic. This points out that the bounds are not able to describe properly the propagation, but a more specific approach is needed. We then move to a system of lattice bosons interacting via long-range interactions. In this case we study two different observables finding completely different results for the same interactions: the spreading of two-body correlations is always ballistic while the one of the one-body correlations ranges from faster-than-ballistic to ballistic. Using our general analytic expressions we find that different parts of the spectrum contribute differently to different observables determining the previous differences. This points out that an observable-dependent notion of locality, missing in the general bounds, have to be developed to correctly describe the time evolution
Hild, Sebastian [Verfasser] y Immanuel [Akademischer Betreuer] Bloch. "Microscopy of quantum many-body systems out of equilibrium / Sebastian Hild ; Betreuer: Immanuel Bloch". München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2016. http://d-nb.info/111747416X/34.
Texto completoMinganti, Fabrizio. "Out-of-Equilibrium Phase Transitions in Nonlinear Optical Systems". Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC004/document.
Texto completoIn this thesis we theoretically study driven-dissipative nonlinear systems, whosedynamics is capture by a Lindblad master equation. In particular, we investigate theemergence of criticality in out-of-equilibrium dissipative systems. We present a generaland model-independent spectral theory relating first- and second-order dissipative phasetransitions to the spectral properties of the Liouvillian superoperator. In the critical region,we determine the general form of the steady-state density matrix and of the Liouvillianeigenmatrix whose eigenvalue defines the Liouvillian spectral gap. We discuss the relevanceof individual quantum trajectories to unveil phase transitions. After these general results,we analyse the inset of criticality in several models. First, a nonlinear Kerr resonator in thepresence of both coherent (one-photon) and parametric (two-photon) driving and dissipation.We then explore the dynamical properties of the coherently-driven Bose-Hubbard and of thedissipative XYZ Heisenberg model presenting a first-order and a second-order dissipativephase transition, respectively. Finally, we investigate the physics of photonic Schrödingercat states in driven-dissipative resonators subject to engineered two-photon processes andone-photon losses. We propose and study a feedback protocol to generate a pure cat-likesteady state
Leyton, Ortega Vicente Ancelmo [Verfasser] y Michael [Akademischer Betreuer] Thorwart. "Quantum noise in nonlinear nanoscale systems out of equilibrium / Vicente Ancelmo Leyton Ortega. Betreuer: Michael Thorwart". Hamburg : Staats- und Universitätsbibliothek Hamburg, 2013. http://d-nb.info/1030366446/34.
Texto completoCavina, Vasco. "Thermodynamics of open quantum systems: from a critical study to the optimization of non-equilibrium heat engines". Doctoral thesis, Scuola Normale Superiore, 2019. http://hdl.handle.net/11384/85921.
Texto completoScarlatella, Orazio. "Driven-Dissipative Quantum Many-Body Systems". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS281/document.
Texto completoMy PhD was devoted to the study of driven-dissipative quantum many-body systems. These systems represent natural platforms to explore fundamental questions about matter under non-equilibrium conditions, having at the same time a potential impact on emerging quantum technologies. In this thesis, we discuss a spectral decomposition of single-particle Green functions of Markovian open systems, that we applied to a model of a quantum van der Pol oscillator. We point out that a sign property of spectral functions of equilibrium systems doesn't hold in the case of open systems, resulting in a surprising ``negative density of states", with direct physical consequences. We study the phase transition between a normal and a superfluid phase in a prototype system of driven-dissipative bosons on a lattice. This transition is characterized by a finite-frequency criticality corresponding to the spontaneous break of time-translational invariance, which has no analog in equilibrium systems. Later, we discuss the mean-field phase diagram of a Mott insulating phase stabilized by dissipation, which is potentially relevant for ongoing experiments. Our results suggest that there is a trade off between the fidelity of the stationary phase to a Mott insulator and robustness of such a phase at finite hopping. Finally, we present some developments towards using dynamical mean field theory (DMFT) for studying driven-dissipative lattice systems. We introduce DMFT in the context of driven-dissipative models and developed a method to solve the auxiliary problem of a single impurity, coupled simultaneously to a Markovian and a non-Markovian environment. As a test, we applied this novel method to a simple model of a fermionic, single-mode impurity
Robinson, Neil Joe. "Pairing, paramagnetism and prethermalization in strongly correlated low-dimensional quantum systems". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:167d164c-e318-49b3-83ea-69b54ec531e0.
Texto completoDroenner, Leon Janek [Verfasser], Alexander [Akademischer Betreuer] Carmele, Andreas [Akademischer Betreuer] Knorr, Andreas [Gutachter] Knorr y Peter [Gutachter] Rabl. "Out-of-equilibrium dynamics of open quantum many-body systems / Leon Janek Droenner ; Gutachter: Andreas Knorr, Peter Rabl ; Alexander Carmele, Andreas Knorr". Berlin : Technische Universität Berlin, 2019. http://d-nb.info/1177881233/34.
Texto completoBuchhold, Michael [Verfasser], Sebastian [Akademischer Betreuer] Diehl y Walter [Akademischer Betreuer] Hofstetter. "Thermalization and Out-of-Equilibrium Dynamics in Open Quantum Many-Body Systems / Michael Buchhold. Betreuer: Sebastian Diehl. Gutachter: Sebastian Diehl ; Walter Hofstetter". Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://d-nb.info/1078205078/34.
Texto completoHauschild, Johannes Michael [Verfasser], Frank [Akademischer Betreuer] Pollmann, Frank [Gutachter] Pollmann y Michael [Gutachter] Knap. "Quantum Many-Body Systems Far Out of Equilibrium — Simulations with Tensor Networks / Johannes Michael Hauschild ; Gutachter: Frank Pollmann, Michael Knap ; Betreuer: Frank Pollmann". München : Universitätsbibliothek der TU München, 2019. http://d-nb.info/1199537772/34.
Texto completoVille, Jean-Loup. "Quantum gases in box potentials : sound and light in bosonic Flatland". Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEE024/document.
Texto completoUltracold atoms have proven to be a powerful platform for studying many-body physics. However the inhomegeneity of atomic clouds induced by potentials commonly used to trap the atoms constitutes a limitation for studies probing large length scales. Here we present the implementation of a new versatile setup to study two-dimensional Bose gases, combining a tunable in-plane box potential with a strong and efficient confinement along the third direction. We study different excitations of the system, either of internal degrees of freedom of the atoms with light scattering, or of their collective motion with phonon propagation. The slab geometry is particularly well suited for light scattering studies. It allows one to probe high atomic densities, leading to strong induced dipole-dipole interactions, while keeping a good enough light transmission for measurements. We monitor the deviation from the single atom behavior for near resonant light by varying the atomic density. We additionally monitor the spreading of photons inside the slab by injecting light only at the center of a disk of atoms. We also investigate collective excitations of the atomic gas. We measure the speed of sound which is linked to the superfluid density of the cloud and compare our results to a two-fluid hydrodynamic model predictions. Using a relevant geometry, we additionally study how an isolated system goes back to equilibrium. This is done by imaging the phase of the resulting Bose-Einstein condensate (BEC) after merging up to twelve BECs
Jussiau, Etienne. "Dynamique des systèmes quantiques ouverts : un niveau quantique discret fortement couplé à un continuum avec une structure de bandes". Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAY032.
Texto completoFollowing the technological advances of the Industrial Revolution, classical thermodynamics was developed in the 19th century in order to understand the conversion of heat into work in newly designed machines. The works of Boltzmann brought another conceptual revolution with statistical mechanics. He demonstrated the microscopical origin of the laws of thermodynamics which actually only describe the macroscopic behaviour of systems in which local thermalization is faster than all other timescales. However, following the growing interest for nanotechnologies, it is now possible to manipulate microscopic systems in which thermalization is slower than the timescales for electron flow. A major technological advance in this field stems from the use of quantum dots, nanoscale devices which confine electrons on such small scales that they spread on discrete energy levels. It is then essential to take into account quantum effects for the study of this type of systems, that is to say to design theoretical tools combining thermodynamics and quantum mechanics.Problems of quantum thermodynamics are often tackled in the framework of the theory of open quantum systems. The general idea of this formalism is to study the dynamics of a “small” quantum system when it is coupled to another much bigger representing the environment. One can then show that the time evolution of the small system can be described by a master equation in the limit where it is weakly coupled to the environment. However, it intuitively seems that the power output of machine would be higher in the context of strong coupling.For problems of electronic transport, the Landauer-Büttiker formalism allows to describe the strong-coupling regime. In this framework, electrons are assumed to solely undergo elastic scattering processes in the central system. All the thermoelectric properties of the machine can then be characterized thanks to the transmission properties of the scatterer. However, this formalism has an important limitation; it ignores the band structure of the reservoirs.Here we have chosen to adopt a different viewpoint to tackle the strong-coupling regime by studying an exactly soluble model. We therefore analyze the Fano-Anderson model describing a discrete level coupled to a continuum. We are particularly interested by the influence of the reservoirs’ band structure. One can indeed show that, under certain conditions, discrete bound states appear in the band gaps of the reservoirs. This state play an important rôle on the dynamics of the discrete at long times: their contribution depends on the initial preparation of the system and gives rise to persistent oscillations of the occupation of the discrete level.We start by deriving the exact solution of the model especially focusing on its long-time behaviour. We then analyze two special cases. First, we study the transport properties of a single-level quantum dot coupled to a semiconductor with single a band gap. A bound state appears in this gap when the coupling to the reservoir exceeds a critical value. We show that this greatly affects the transport properties of the device. We then study the case of reservoirs described by a tight-binding model which density of states consists of a single finite-range energy band. We show that a discrete level coupled to such reservoir behaves like a many-level system as its local density of states and transmission function exhibits multiple resonances
Gonzalez, Yuber Ferney Perez. "Leptogênese e mecanismo de See-Saw de tipo I na teoria quântica de campos fora do equilíbrio térmico". Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-24092014-151403/.
Texto completoOne of the most important problems that is needed to solve by the Elementary Particle Physics as well as by the Cosmology is the existence of baryonic asymmetry. Among the most attractive scenarios of dynamic generation of baryonic asymmetry (Baryogenesis) is the so-called Leptogenesis. In that scenario, a leptonic asymmetry is treated in such a way that it will be converted in baryonic asymmetry by non-perturbative processes mediated by sphalerons. In the simplest realization of Leptogenesis, that will be studied in this disertation, heavy right-handed neutrinos, produzed thermally, decay violating CP generating a leptonic asymmetry in these decays. The principal attractive of this scenario is that it connects two apparently different scales, the scale of leptonic asymmetry generation and the scale of masses and oscillations of the active neutrinos through the See-Saw mechanism. The usual study of the leptogenesis uses Boltzmann equations in order to determine the temporal evolution of the asymmetry. However, the Boltzmann equation is a semiclassical equations, since, on one side, it is formulated for a classical function in phases space, the distribution function, but, on the other hand, the collision term involves quantities obtained in the Quantum Field Theory at zero temperature. In particular, Boltzmann formulation does not allow to describe quantum phenomena such coherent oscillations and effects of decoherence and interference. Indeed, a proper quantum description of the evolution of the leptonic asymmetry must be obtained in the context of the Non-Equilibrium Quantum Field Theory. The Schwinger-Keldysh formalism allows to perform this. In this dissertation, leptogenesis is described using the Schwinger-Keldysh formalism for the case in which there are three right-handed neutrinos without a definite mass hierarchy.
Wendenbaum, Pierre. "Intrication et dynamique de trempe dans les chaînes de spins quantiques". Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0170/document.
Texto completoThe study carried in this thesis concerns the dynamics of out-Of-Equilibrium quantum systems, and more particularly their entanglement properties. Indeed, entanglement became a fundamental concept in modern physics, especially with the development of quantum information. We have in a first part studied the dynamics of a model of bosons on a lattice after the quench of their trapping potential. In the hard-Core limit, we developed an hydrodynamical theory which perfectly reproduced the observed behavior. Then, we have looked at the dynamics of two defect spins coupled to an Ising chain. When these defects have been prepared into a separable state, we have established a formula giving the evolution of the reduced density matrix, allowing us to have access to the entanglement create through the coupling to the chain. We considered then the case of two initially entangled defect spins, and we studied the influence of a non-Equilibrium environment on the disentanglement properties. Finally, the last part of this thesis is devoted to the study of a system coupled to an environment by means of the repeated interactions process. We studied the relaxation of the system in two different time regimes. For short times, the state is well described by a non-Equilibrium-Steady-State, in which we highlighted the scaling properties of some observables. For long times, the system reaches an equilibrium steady state made of a product of Bell states
Molineri, Anaïs. "Un nouveau dispositif pour étudier la relaxation d'un système quantique à N corps". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLO013/document.
Texto completoThis manuscript presents the first steps of a new ultracold atoms experiment using strontium 84. The aim of this experiment is to study the relaxation dynamics of quantum gases initially prepared in an out-of-equilibrium state. This experiment will include a quantum gas microscope, allowing us to measure spatial correlation functions in two-dimensionnal systems. The current state of the construction allows us to generate both magneto-optical trap of strontium: along its wide transition at 461 nm and its narrow transition at 689 nm. Concurrently with the experimental setup, we carried out works on a reconstruction algorithm required for the future data processing of the microscope images. This manuscript details experimental aspects, justifying their choices, and presents the current state of work on the reconstruction algorithm. There are still steps to complete the experimental setup: add a chamber where we will make the measurements to the vaccuum system, set up the quantum gaz microscope and all the required optics to transport the atomic clouds between two vaccuum chambers, to reach Bose-Einstein condensation and to confine the atoms in two-dimensionnal optical traps
FRANCESCHINI, PAOLO. "NOVEL SCHEMES FOR ULTRAFAST MANIPULATION OF QUANTUM MATERIALS". Doctoral thesis, Università Cattolica del Sacro Cuore, 2022. http://hdl.handle.net/10280/111822.
Texto completoThe possibility to control the electronic properties on-demand on an ultrafast time scale represents one of the most exciting challenges towards the realization of new generation photonic and electronic devices. Triggered by this, in the last decades the research activity focused its attention to different solid-state platforms. Among all, dielectric nanostructures (and metamaterials) and correlated materials represent the most promising candidate for the implementation of devices endowed by new functionalities. Apart from the specific features making dielectrics more suitable for photonic applications and correlated materials for electronic devices, both categories exhibit new functionalities if subjected to an external stimulus in the form of excitation light pulses shorter than the relaxation timescale of the internal degrees of freedom of the system. Indeed, the out-of-equilibrium state achieved upon photoexcitation exhibits electronic and optical properties highly different from those at equilibrium. Therefore, the aim of this thesis work consists in the development of new methods and experimental approaches capable to induce, measure, and control new functionalities in complex materials on an ultrafast time scale.
Kasztelan, Christian [Verfasser]. "Strongly interacting quantum systems out of equilibrium : ultracold quantum gases and magnetic systems / Christian Kasztelan". 2010. http://d-nb.info/1009820206/34.
Texto completoIadecola, Thomas. "Designing topological quantum matter in and out of equilibrium". Thesis, 2017. https://hdl.handle.net/2144/27071.
Texto completoKarrasch, Christoph [Verfasser]. "The functional renormalization group for zero-dimensional quantum systems in and out of equilibrium / vorgelegt von Christoph Karrasch". 2010. http://d-nb.info/100962234X/34.
Texto completoSchmitt, Markus. "Dynamics of isolated quantum many-body systems far from equilibrium". Doctoral thesis, 2018. http://hdl.handle.net/11858/00-1735-0000-002E-E32A-F.
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