Download or read book Localization and Slow Thermalization in Quantum Many body Systems written by Wen Wei Ho and published by . This book was released on 2017 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Interplay of Localization and Interactions in Quantum Many body Systems written by Shankar Iyer and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Disorder and interactions both play crucial roles in quantum transport. Decades ago, Mott showed that electron-electron interactions can lead to insulating behavior in materials that conventional band theory predicts to be conducting. Soon thereafter, Anderson demonstrated that disorder can localize a quantum particle through the wave interference phenomenon of Anderson localization. Although interactions and disorder both separately induce insulating behavior, the interplay of these two ingredients is subtle and often leads to surprising behavior at the periphery of our current understanding. Modern experiments probe these phenomena in a variety of contexts (e.g. disordered superconductors, cold atoms, photonic waveguides, etc.); thus, theoretical and numerical advancements are urgently needed. In this thesis, we report progress on understanding two contexts in which the interplay of disorder and interactions is especially important. The first is the so-called "dirty" or random boson problem. In the past decade, a strong-disorder renormalization group (SDRG) treatment by Altman, Kafri, Polkovnikov, and Refael has raised the possibility of a new unstable fixed point governing the superfluid-insulator transition in the one-dimensional dirty boson problem. This new critical behavior may take over from the weak-disorder criticality of Giamarchi and Schulz when disorder is sufficiently strong. We analytically determine the scaling of the superfluid susceptibility at the strong-disorder fixed point and connect our analysis to recent Monte Carlo simulations by Hrahsheh and Vojta. We then shift our attention to two dimensions and use a numerical implementation of the SDRG to locate the fixed point governing the superfluid-insulator transition there. We identify several universal properties of this transition, which are fully independent of the microscopic features of the disorder. The second focus of this thesis is the interplay of localization and interactions in systems with high energy density (i.e., far from the usual low energy limit of condensed matter physics). Recent theoretical and numerical work indicates that localization can survive in this regime, provided that interactions are sufficiently weak. Stronger interactions can destroy localization, leading to a so-called many-body localization transition. This dynamical phase transition is relevant to questions of thermalization in isolated quantum systems: it separates a many-body localized phase, in which localization prevents transport and thermalization, from a conducting ("ergodic") phase in which the usual assumptions of quantum statistical mechanics hold. Here, we present evidence that many-body localization also occurs in quasiperiodic systems that lack true disorder.

Download or read book NMR Studies of Quantum Thermalization written by Pai Peng (Scientist in electrical engineering and computer science) and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: To understand many-body localized (MBL) systems, an algorithm to compute local integrals of motion (LIOMs) is designed. From LIOMs, various localization lengths are extracted and their critical behavior is studied.

Download or read book Entanglement and Thermalization Many Body Quantum Systems written by Philip Crowley and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Strongly Interacting Quantum Systems out of Equilibrium written by Thierry Giamarchi and published by Oxford University Press. This book was released on 2016-07-07 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last decade new experimental tools and theoretical concepts are providing new insights into collective nonequilibrium behavior of quantum systems. The exquisite control provided by laser trapping and cooling techniques allows us to observe the behavior of condensed bose and degenerate Fermi gases under nonequilibrium drive or after `quenches' in which a Hamiltonian parameter is suddenly or slowly changed. On the solid state front, high intensity short-time pulses and fast (femtosecond) probes allow solids to be put into highly excited states and probed before relaxation and dissipation occur. Experimental developments are matched by progress in theoretical techniques ranging from exact solutions of strongly interacting nonequilibrium models to new approaches to nonequilibrium numerics. The summer school `Strongly interacting quantum systems out of equilibrium' held at the Les Houches School of Physics as its XCIX session was designed to summarize this progress, lay out the open questions and define directions for future work. This books collects the lecture notes of the main courses given in this summer school.

Download or read book Entanglement in Spin Chains written by Abolfazl Bayat and published by Springer Nature. This book was released on 2022-09-26 with total page 549 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers recent developments in the understanding, quantification, and exploitation of entanglement in spin chain models from both condensed matter and quantum information perspectives. Spin chain models are at the foundation of condensed matter physics and quantum information technologies and elucidate many fundamental phenomena such as information scrambling, quantum phase transitions, and many-body localization. Moreover, many quantum materials and emerging quantum devices are well described by spin chains. Comprising accessible, self-contained chapters written by leading researchers, this book is essential reading for graduate students and researchers in quantum materials and quantum information. The coverage is comprehensive, from the fundamental entanglement aspects of quantum criticality, non-equilibrium dynamics, classical and quantum simulation of spin chains through to their experimental realizations, and beyond into machine learning applications.

Download or read book Manipulating Quantum Systems written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2020-10-14 with total page 315 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of atomic, molecular, and optical (AMO) science underpins many technologies and continues to progress at an exciting pace for both scientific discoveries and technological innovations. AMO physics studies the fundamental building blocks of functioning matter to help advance the understanding of the universe. It is a foundational discipline within the physical sciences, relating to atoms and their constituents, to molecules, and to light at the quantum level. AMO physics combines fundamental research with practical application, coupling fundamental scientific discovery to rapidly evolving technological advances, innovation and commercialization. Due to the wide-reaching intellectual, societal, and economical impact of AMO, it is important to review recent advances and future opportunities in AMO physics. Manipulating Quantum Systems: An Assessment of Atomic, Molecular, and Optical Physics in the United States assesses opportunities in AMO science and technology over the coming decade. Key topics in this report include tools made of light; emerging phenomena from few- to many-body systems; the foundations of quantum information science and technologies; quantum dynamics in the time and frequency domains; precision and the nature of the universe, and the broader impact of AMO science.

Download or read book Periodically driven Quantum Many body Systems Many body Localization and Machine Learning written by Pedro Ponte and published by . This book was released on 2018 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: Despite the exponentially large amount of information required in the quantum description of many-body systems, finite size numerical simulations have paved the way for recent progress in the understanding of quantum phases of matter both in and out-of-equilibrium. In this spirit, using exact diagonalization for a small number of spins ~ 20, first, we investigate the fate of both ergodic quantum many-body systems that thermalize at long times and systems with quenched disorder that exhibit many-body localization (MBL) and fail to thermalize (due to an extensive set of local conserved degrees of freedom) under periodic driving. Ergodic systems always delocalize in energy space and heat up to infinite temperature, for both local driving, in which the time dependence of the Hamiltonian is restricted to a few contiguous degrees of freedom, and global driving. On the other hand, MBL systems remain localized at finite energy density for local driving, while in the case of global driving these systems can either heat up to infinite temperature or remain localized depending on the parameters of the drive. Underlying the latter is the emergence of an effective time independent MBL Hamiltonian describing the long time dynamics of the system. These numerical predictions have recently been verified experimentally in a one dimensional quasi-disordered optical lattice of interacting fermions wherein unitary time evolution can be experimentally probed. Subsequently, we study the stability of MBL systems with respect to another perturbation, in this case by thermal inclusions, which remains poorly understood.

Download or read book Entanglement and Thermalization in Many Body Quantum Systems written by P. J. D. Crowley and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Prethermalization and Localization in Quantum Spin Chains written by Pai Peng (S. M.) and published by . This book was released on 2019 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: How can a quantum many-body system escape the fate of thermalization is of importance to both fundamental study of quantum statistical physics and applications in quantum devices. Here we develop novel experimental and computational tools to address this question. First, novel control techniques are introduced to investigate prethermalization, a process where a quantum system fails to thermalize on a practical timescale. Prethermalization is demonstrated by measuring out-of-time ordered (OTO) correlations in nuclear spin systems with magnetic resonance techniques. Hamiltonian engineering enables tuning the strength of spin-spin interactions and of a transverse magnetic field in a spin chain system, as well as to invert the Hamiltonian sign to reveal OTO correlations. The experiments reveal that at high fields an emergent conserved quantity arises due to prethermalization, and the OTO commutator involving such prethermal conserved quantity saturates after a short time. These results not only introduce a new protocol to measure out-of-time ordered correlations, but also provide new insights in the study of prethermalization. Second, the role of localization in avoiding thermalization is analyzed with a novel computational method. Introducing a novel, non-perturbative approach, a complete set of local integrals of motion (LIOMs) in many-body localization systems can be computed efficiently. By maximizing the overlap between LIOMs and physical spin operators in real space, the set of LIOMs satisfies the desired exponential decay of weight of LIOMs in real space. This allows comparing localization lengths extracted from the LIOM weights, their interactions, and dephasing dynamics, which reveals interesting aspects of many-body localization. This scheme is immune to accidental resonances and can be applied even at the phase transition point, providing a novel tool to study the microscopic features of the phenomenological model of many-body localization. The results presented here provide insight into two many-body mechanisms for avoiding thermalization and pave the way for further exploration to unravel the dynamics of complex quantum spin systems.

Download or read book Supercomputing Frontiers written by Dhabaleswar K. Panda and published by Springer Nature. This book was released on 2022-06-30 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book constitutes the refereed proceedings of the 7th Asian Conference Supercomputing Conference, SCFA 2022, which took place in Singapore in March 2022. The 8 full papers presented in this book were carefully reviewed and selected from 21 submissions. They cover a range of topics including file systems, memory hierarchy, HPC cloud platform, container image configuration workflow, large-scale applications, and scheduling.

Download or read book Disorder Free Localization written by Adam Smith and published by Springer. This book was released on 2019-07-01 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is a contribution at the intersection of a number of active fields in theoretical and experimental condensed matter, particularly those concerned with disordered systems, integrable models, lattice gauge theories, and non-equilibrium quantum dynamics. It contributes an important new facet to our understanding of relaxation in isolated quantum systems by conclusively demonstrating localization without disorder for the first time, answering a long-standing question in this field. This is achieved by introducing a family of models – intimately related to paradigmatic condensed matter models – and studying their non-equilibrium dynamics through a combination of exact analytical mappings and an array of numerical techniques. This thesis also makes contributions relevant to the theory of quantum chaotic behaviour by calculating novel, and often intractable, entanglement measures and out-of-time-ordered correlators. A concrete and feasible proposal is also made for the experimental realization and dynamical study of the family of models, based on currently available technologies.

Download or read book Time Crystals written by Krzysztof Sacha and published by Springer Nature. This book was released on 2020-09-24 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides the first comprehensive description of time crystals which have a repeating structure in time. It introduces the fundamental concepts behind time crystals and explores the many different branches of this new research area. The book starts with the original idea of the time crystallization in quantum systems as introduced by Wilczek and follows the development of the field up to the present day. Both spontaneous formation of crystalline structures in time and concepts of the condensed matter physics in the time domain, ranging from Anderson localization in time to many-body systems with exotic interactions, are described. The prospect of creation of novel objects by means of time engineering is also presented. The book assumes knowledge of quantum mechanics to the graduate level. It serves as a valuable reference with pointers to future research directions for graduate students and senior scientists alike.

Download or read book Methods for Thermalization and Equilibration Dynamics in Quantum Many Body Systems written by Asli Cebe and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Thermalization and Out of Equilibrium Dynamics in Open Quantum Many Body Systems written by Michael Buchhold and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Analogue Quantum Simulation written by Dominik Hangleiter and published by Springer Nature. This book was released on 2022-01-21 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents fresh insights into analogue quantum simulation. It argues that these simulations are a new instrument of science. They require a bespoke philosophical analysis, sensitive to both the similarities to and the differences with conventional scientific practices such as analogical argument, experimentation, and classical simulation. The analysis situates the various forms of analogue quantum simulation on the methodological map of modern science. In doing so, it clarifies the functions that analogue quantum simulation serves in scientific practice. To this end, the authors introduce a number of important terminological distinctions. They establish that analogue quantum ‘computation' and ‘emulation' are distinct scientific practices and lead to distinct forms of scientific understanding. The authors also demonstrate the normative value of the computation vs. emulation distinction at both an epistemic and a pragmatic level. The volume features a range of detailed case studies focusing on: i) cold atom computation of many-body localisation and the Higgs mode; ii) photonic emulation of quantum effects in biological systems; and iii) emulation of Hawing radiation in dispersive optical media. Overall, readers will discover a normative framework to isolate and support the goals of scientists undertaking analogue quantum simulation and emulation. This framework will prove useful to both working scientists and philosophers of science interested in cutting-edge scientific practice.

Download or read book Thermal and Non thermal Behavior of Quantum Systems written by Sebastian Wenderoth and published by . This book was released on 2022* with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Thermalization is one of the most prominent physical effects in our everyday experience of the world. It refers to the process of a system, which is in a non-equilibrium state, relaxing to a thermal equilibrium. The remarkable property of this process is that the thermal equilibrium state is determined by few macroscopic properties of the system, like the total energy of the system. The information about the precise initial configuration of the system is lost during this process: on a macroscopic scale, thermalization is an irreversible process. This is particularly surprising since the fundamental laws of motion, which describe how the microscopic particles move, is formally reversible at all times. Bridging this apparent contradiction between the fundamental laws of nature, prescribed by Newton's or Schrödinger's equation, and the emergence of thermalization on a macroscopic scale is a non-trivial question. Nowadays, the emergence of thermalization in a quantum mechanical system is understood in a local sense: subsystems are driven towards thermal equilibrium by the interaction with their remainder. The remainder acts as an effective environment and in the long-time limit the state of the subsystem becomes independent of the initial configuration. Over the last decade it was realized that thermalization can be decomposed into different aspects showing that systems can exhibit qualitatively different non-thermal behaviors depending on which aspects of thermalization is violated. Although the emergence of thermal behavior can be explained in this way and non-thermal behavior was found in a variety of different systems, there are still many open questions. In this thesis we contribute to three of these open question: First, we analyze environment- induced effects and investigate in which situations an environment can thermalize a system. Second, we examine the local memory in thermal and non-thermal systems and how the information about the initial state distributes over the system. Third, we investigate the stability of a many-body localized system, one prominent example of a non-thermalizing systems, with respect to long-range interactions. To address these different issues, we consider three different model systems: the spin-boson model, the disordered XXZ Heisenberg spin chain, and a centrally coupled spin chain, respectively. Our analysis is based on a combination of analytic and numerical approaches. Based on the time-evolution of subsystems, we propose a measure to quantify the local memory in subsystems, which can be used as an indicator for thermal and non-thermal behavior in quantum systems. To simulate the dynamics of the different systems we employ exact diagonalization and the multilayer multiconfiguration time-dependent Hartree approach. While the first can be used to simulate the dynamics of small systems for arbitrary times, the later can be used to simulate the dynamcis of large systems at short and intermediate times. Our findings demonstrate that all considered systems have a parameter regime in which they exhibit thermal behavior, i.e. subsystems approach a unique equilibrium state which is vii determined only by macroscopic observables. The relaxation towards the equilibrium state, however, is qualitatively different for the different models and exhibit a rich and interesting dynamical behavior. In the weak coupling regime of the spin-boson model we find a transition from coherent to incoherent equilibration as well as a partial back flow of information, giving rise to non-Markovian dynamics. In the thermal phase of the disordered XXZ Heisenberg spin chain we identify different delocalization mechanisms, leading to different time scales in the relaxation. In the strong coupling regime of the centrally coupled spin chain we find that the spins of the chain are thermalized by the long-range interactions. On the other hand, all systems have a parameter regime in which they show non-thermal behavior. Depending on the spectrum of the environment, we find different non-thermal behaviors in the strong coupling regime of the spin-boson model. For a gapped spectrum we find a failure of subsystem equilibration, i.e. the state of the spin remains time-dependent at all times. For an Ohmic spectral density the spin localizes in its initial state, and thus retains information about the initial state in local observables. We find a similar effect in the disordered XXZ Heisenberg spin chain in the many-body localized phase and in the weak and intermediate coupling regime of the centrally coupled spin chain: some information about the initial state is stored in the asymptotic state of the spins. Furthermore, our results show that the initial state of a subsystem can influence the asymptotic state of the system if macroscopic observables, like the total energy, are influenced by the initial state. This can be seen in the asymptotic state of the central degree of freedom in the centrally coupled spin chain