Download or read book Real time Simulations of Open Quantum Spin Systems Driven by Measurement written by and published by . This book was released on 2015 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Real time Simulation of Open Quantum Spin Systems Driven by Measurements written by Franziska Schranz and published by . This book was released on 2015 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantum Classical Correspondence and Entanglement in Periodically Driven Spin Systems written by Meenu Kumari and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation sets out to examine some fundamental open questions in quantum physics regarding quantum-classical correspondence in regular versus chaotic systems. Specifically, we study these questions using approaches in quantum information science in an experimentally realized textbook model of quantum chaos - the quantum kicked top (QKT). The effect of classical chaos on the generation of entanglement in spin systems has been a field of active research for a couple of decades. Whether high entanglement in these systems is a hallmark of chaos or not remains a widely debated topic. We explain the connection between entanglement and chaos in spin systems and resolve previous conflicting results. The previous studies have mostly drawn conclusions from numerical work on a few initial states in regular versus chaotic regions. We instead focus on stable and unstable periodic orbits because chaos emerges around unstable periodic orbits. We first propose a new set of criteria for determining whether quantum evolution will correspond to the classical trajectory in a localized manner at stable periodic orbits in periodically driven systems. These criteria can be used to calculate the quantum numbers that will lead to quantum-classical correspondence even in a deep quantum regime, and thus to quantify the well-known Bohr correspondence principle. Next, we analytically show a direct connection between entanglement generation and a measure of delocalization of a quantum state in spin systems. More concretely, we describe a method to calculate an upper bound on entanglement generation in any bipartition of spin systems, where the upper bound is a function of trace distance between the evolved state and the most localized classical-like separable states. This method along with our criteria for localized evolution enables us to explain the behaviour of entanglement in both deep quantum and semiclassical regimes for regular as well as chaotic regions. Hence, our analysis resolves the long-standing debates regarding the connection between classical chaos and quantum entanglement in deep quantum and semiclassical regimes. In addition to the study of entanglement, we perform the first study of nonlocality, and the effect of chaos on its generation in the QKT. Since nonlocality and entanglement are inequivalent quantum resources, the effect of chaos on nonlocality merits an explicit study. Violations of Bell inequalities in the presence of spacelike separation among the subsystems imply nonlocality - meaning nonlocal correlations between subsystems of the total spin system. We show that the QKT evolution can lead to states that violate multiqubit Bell inequalities and hence provides a deterministic method to prepare nonlocal quantum states. Our numerical results suggest a correlation between delocalized evolution of a pure quantum state and generation of nonlocality in the quantum state. We further demonstrate that dynamical tunnelling - a classically forbidden phenomenon - in the QKT leads to the generation of Greenberger-Horne-Zeilinger (GHZ)-like states for even numbers of qubits. We analytically prove that these states are maximally nonlocal. On the other hand, we numerically show that any reduced state of the QKT obtained by tracing out a subsystem of the total spin system does not violate Bell inequalities. We provide an analytical explanation of the numerical results for $2-$qubit reduced states by formulating and proving two general theorems regarding $2-$qubit Bell inequalities. These theorems imply that any $2-$qubit mixed state having a symmetric extension or symmetric purification cannot violate the Clauser-Horne-Shimony-Holt inequality. This highlights fundamental connections between two important and distinct concepts in quantum information science - Bell inequalities and symmetric extension of quantum states. Apart from providing deeper insights into the fundamental questions of quantum-classical correspondence and new approaches to analyze quantum chaos, the methods developed in this thesis can be used to design quantum systems that can efficiently generate entanglement and nonlocality. Thus, our results could have interesting applications in quantum computing and quantum information science.
Download or read book Quantum Many Body Physics in Open Systems Measurement and Strong Correlations written by Yuto Ashida and published by Springer Nature. This book was released on 2020-01-06 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book studies the fundamental aspects of many-body physics in quantum systems open to an external world. Recent remarkable developments in the observation and manipulation of quantum matter at the single-quantum level point to a new research area of open many-body systems, where interactions with an external observer and the environment play a major role. The first part of the book elucidates the influence of measurement backaction from an external observer, revealing new types of quantum critical phenomena and out-of-equilibrium dynamics beyond the conventional paradigm of closed systems. In turn, the second part develops a powerful theoretical approach to study the in- and out-of-equilibrium physics of an open quantum system strongly correlated with an external environment, where the entanglement between the system and the environment plays an essential role. The results obtained here offer essential theoretical results for understanding the many-body physics of quantum systems open to an external world, and can be applied to experimental systems in atomic, molecular and optical physics, quantum information science and condensed matter physics.
Download or read book Quantum Dissipative Systems written by Ulrich Weiss and published by World Scientific. This book was released on 2012 with total page 587 pages. Available in PDF, EPUB and Kindle. Book excerpt: Starting from first principles, this book introduces the fundamental concepts and methods of dissipative quantum mechanics and explores related phenomena in condensed matter systems. Major experimental achievements in cooperation with theoretical advances have brightened the field and brought it to the attention of the general community in natural sciences. Nowadays, working knowledge of dissipative quantum mechanics is an essential tool for many physicists. This book -- originally published in 1990 and republished in 1999 and and 2008 as enlarged second and third editions -- delves significantly deeper than ever before into the fundamental concepts, methods and applications of quantum dissipative systems.This fourth edition provides a self-contained and updated account of the quantum mechanics of open systems and offers important new material including the most recent developments. The subject matter has been expanded by about fifteen percent. Many chapters have been completely rewritten to better cater to both the needs of newcomers to the field and the requests of the advanced readership. Two chapters have been added that account for recent progress in the field. This book should be accessible to all graduate students in physics. Researchers will find this a rich and stimulating source.
Download or read book Spin Dynamics of Open Quantum Systems Driven by Spin exchange Collisions written by Jens Nettersheim and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Static and Dynamic Properties of low dimensional Quantum Spin Systems written by Simon Nils Grossjohann and published by Cuvillier Verlag. This book was released on 2010-08-17 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: In my thesis, static and dynamic properties of low-dimensional spin models were studied by means of a state of the art QMC method (SSE). As one among many numerical algorithms (e.g. DMRG, ED), the QMC proved to be a very flexible and high performance tool with access to dynamic correlation functions at finite temperatures and finite magnetic fields within the thermodynamic limit1. After detailed introduction of the QMC’s basic implementation, I provided yet unpublished information about the measurement of transverse (and longitudinal) imaginary time correlation functions for the spin S Heisenberg model. In addition to that, complications of the analytic continuation to the real axis were explained and two common Maximum Entropy algorithms (Bryan and Meshkov) introduced briefly. In my thesis, both algorithms have been implemented and contrasted in regard to their performance and quality of the continuation, clearly favoring Bryan’s method which is a standard least square algorithm based on Newton iterations with however highly optimized search directions in the multi-dimensional solution space.
Download or read book Crossover Time in Quantum Boson and Spin Systems written by Gennady P. Berman and published by Springer. This book was released on 2014-03-12 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Realizing Quantum Spin Models with 7Li Atoms in an Optical Lattice written by Ivana Ljubomirova Dimitrova and published by . This book was released on 2020 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum spin Hamiltonians are paradigmatic models, which display different kinds of quantum phase transitions, strongly-correlated and topological ground states, and various regimes of transport. Expanding their significance, many mappings exist between quantum spin models and other systems in different areas of physics, mathematics, and beyond. Even though quantum spin models have been studied extensively, there are still many open questions. Simulating these Hamiltonians with the system of ultracold atoms in optical lattices provides a new perspective with the wide tunability of parameters and the minimal coupling to the environment. The mapping involves using the Mott insulating state of ultracold atoms in optical lattices, where the energy of a second-order tunneling process (superexchange) maps to the parameters of a Heisenberg model. This thesis provides a detailed roadmap for the design and building of such a quantum simulator with 7Li atoms in optical lattices. Each step of the process is described, together with the methods and techniques used for the building and the characterization of the physical system. A focus is placed on using the Mott insulator as a starting point for spin physics experiments and, in particular, on the characterization and improvements of the mapping from a density sector description to a spin sector description of the system. Several schemes for implementing and studying spin systems are presented. In particular, the feasibility of implementing the Heisenberg spin-1/2 and spin-1 models in this system is described. The tilted lattice is presented as a tool for studying pure superexchange-driven dynamics and for increasing their timescale by suppressing first order tunneling and the role of number defects. The first measurements and the tuning with this machine of superexchange-driven dynamics over a wide range in the anisotropic Heisenberg spin-1/2 models are presented. Finally, the versatility of the BEC 5 machine is showcased by a study which does not involve an optical lattice. It explores the realization of an exotic quantum phase, a supersolid, in a new way. After many years of building and improvements, the BEC 5 machine emerges as a repeatable and reliable quantum simulator which has a clear scientific agenda of exploring many-body ground states and non-equilibrium dynamics.
Download or read book A Trapped Ion Quantum Simulator for Two dimensional Spin Systems written by Marissa Danielle D'Onofrio and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Universal, fault-tolerant quantum computing would require millions of physical qubits to practically implement most proposed algorithms, a target currently out of reach of experimental capability. In the near term, noisy systems on the order of tens of qubits can employ quantum simulation of particular Hamiltonians to surpass classical computational abilities and solve interesting problems. In particular, one-dimensional (1D) ion chains in radiofrequency (RF) traps have seen remarkable success in simulating 1D quantum spin systems. A comparable ability to manipulate two-dimensional (2D) ion crystals in RF traps would significantly expand the class of systems accessible to quantum simulation. Notably, 2D ion arrays are conducive to studies of many-body systems such as geometrically frustrated lattices, topological materials, and spin-liquid states.In this thesis, I present advances toward the goal of creating programmable, "radial-2D" arrays of trapped 171Yb+ ions for quantum simulation. Qubits are embedded within two hyperfine electronic energy levels, cooled to their motional ground state, and measured via spin-dependent fluorescence. A precisely controlled entangling mechanism allows for the creation of a wide variety of spin models, including Ising or Heisenberg interactions. We present an experimental study which establishes radial-2D crystals of 171Yb+ ions as a robust platform for quantum simulation, through characterization of ion positions, structural phases, normal mode frequencies, and effects from RF heating. We also design and experimentally demonstrate a new open-endcap, blade-style RF trap which can confine and resolve large numbers of ions in the radial-2D crystal phase. Finally, we examine other challenges faced by trapped ion systems: optimally cooling to the motional ground state, accurately determining ion temperature, and measuring susceptibility to the presence of ionizing radiation.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theory and Simulations of Interacting Quantum Systems written by A. Bariş Özgüler and published by . This book was released on 2020 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, we cover several topics from interacting quantum systems in the setting of quantum information algorithms and devices. The thesis is divided into two parts. In the first part, we study interacting spin-1/2 systems in the presence of uniform or disordered field. In the second part, we study novel multiterminal Josephson junctions. We first analyze how a disordered spin system responds to a local drive. The response behavior of the system depends on the disorder strength. We show that one can obtain the phase of the system using the statistical measures of the response. We perform fidelity susceptibility and experimentally accessible spin variance calculations to identify whether the system is in the many-body localized or ergodic regime. We show that the results of these two approaches are correlated to each other and both can be used to find the phase of the system. We further propose a steering method for the random spin systems to speed up the quantum adiabatic algorithm (QAA). We utilize counterdiabatic driving techniques to form 1-spin and cluster steering terms. We compare the efficiency of our steered QAA to the efficiencies of conventional QAA and classical optimization. We obtain a large parameter range in which steering provides speed-up. Next, we study fluxonium qubit systems. Their strong anharmonicity, long coherence time and strong coupling ability makes them a good fit for spin-1/2 system simulations. We study quantum phase diagram of fluxonium qubit chains. We identify the phase transition boundary using the fidelity susceptibility techniques. We discuss some Ising spin chain simulations that can be performed using the fluxonium qubit chains. Finally, we investigate multiterminal Josephson junctions. These devices work in high dimensional phase spaces due to phase contributions from extra terminals. Tuning the parameters of junctions with special geometries by gate voltage and magnetic field leads to multiterminal Josephson effect. The transition characteristics is measured by the shape and area of the multidimensional critical current contour. We explore the mechanisms behind this transition by using the scattering theory and microscopic computation of the wave functions.
Download or read book Irreversible Real time Dynamics of Spin Systems written by Leon Mixa and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantum Computers Algorithms and Chaos written by Giulio Casati and published by IOS Press. This book was released on 2006 with total page 650 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum Information Processing and Communication (QIPC) has the potential to revolutionize many areas of science and technology. This book covers the following topics: introduction to quantum computing; quantum logic, information and entanglement; quantum algorithms; error-correcting codes for quantum computations; quantum communication; and more."
Download or read book Quantum Thermodynamics written by Jochen Gemmer and published by Springer Science & Business Media. This book was released on 2009-10-21 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the years enormous effort was invested in proving ergodicity, but for a number of reasons, con?dence in the fruitfulness of this approach has waned. — Y. Ben-Menahem and I. Pitowsky [1] Abstract The basic motivation behind the present text is threefold: To give a new explanation for the emergence of thermodynamics, to investigate the interplay between quantum mechanics and thermodynamics, and to explore possible ext- sions of the common validity range of thermodynamics. Originally, thermodynamics has been a purely phenomenological science. Early s- entists (Galileo, Santorio, Celsius, Fahrenheit) tried to give de?nitions for quantities which were intuitively obvious to the observer, like pressure or temperature, and studied their interconnections. The idea that these phenomena might be linked to other ?elds of physics, like classical mechanics, e.g., was not common in those days. Such a connection was basically introduced when Joule calculated the heat equ- alent in 1840 showing that heat was a form of energy, just like kinetic or potential energy in the theory of mechanics. At the end of the 19th century, when the atomic theory became popular, researchers began to think of a gas as a huge amount of bouncing balls inside a box.
Download or read book Tensor Network Contractions written by Shi-Ju Ran and published by Springer Nature. This book was released on 2020-01-27 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tensor network is a fundamental mathematical tool with a huge range of applications in physics, such as condensed matter physics, statistic physics, high energy physics, and quantum information sciences. This open access book aims to explain the tensor network contraction approaches in a systematic way, from the basic definitions to the important applications. This book is also useful to those who apply tensor networks in areas beyond physics, such as machine learning and the big-data analysis. Tensor network originates from the numerical renormalization group approach proposed by K. G. Wilson in 1975. Through a rapid development in the last two decades, tensor network has become a powerful numerical tool that can efficiently simulate a wide range of scientific problems, with particular success in quantum many-body physics. Varieties of tensor network algorithms have been proposed for different problems. However, the connections among different algorithms are not well discussed or reviewed. To fill this gap, this book explains the fundamental concepts and basic ideas that connect and/or unify different strategies of the tensor network contraction algorithms. In addition, some of the recent progresses in dealing with tensor decomposition techniques and quantum simulations are also represented in this book to help the readers to better understand tensor network. This open access book is intended for graduated students, but can also be used as a professional book for researchers in the related fields. To understand most of the contents in the book, only basic knowledge of quantum mechanics and linear algebra is required. In order to fully understand some advanced parts, the reader will need to be familiar with notion of condensed matter physics and quantum information, that however are not necessary to understand the main parts of the book. This book is a good source for non-specialists on quantum physics to understand tensor network algorithms and the related mathematics.
Download or read book Quantum Measurement and Control written by Howard M. Wiseman and published by Cambridge University Press. This book was released on 2010 with total page 477 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modern quantum measurement for graduate students and researchers in quantum information, quantum metrology, quantum control and related fields.
