Crossover-Time in Quantum Boson and Spin Systems PDF Download

Author: Gennady P. Berman
Publisher: Springer Science & Business Media
ISBN: 3540484159
Category : Science
Languages : en
Pages : 279

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Book Description
The authors compare classical and quantum dynamics in the quasiclassical region of parameters and under the condition of unstable (chaotic) classical behavior. They estimate the characteristic time-scale at which classical and quantum solutions start to differ significantly. The method is based on exact equations for time-dependent expectation values in boson and spin coherent states, and applies to rather general Hamiltonians with many degrees of freedom. The authors develop a consistent dynamical theory for quantum nonintegrable Hamiltonians and provide explicit examples of classical-quantum "crossover-time", a very common and fundamental phenomenon in quantum nonintegrable systems. This book can be recommended to graduate students and to specialists.

Author: Paul Busch
Publisher: Springer Science & Business Media
ISBN: 3540492399
Category : Science
Languages : en
Pages : 237

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Book Description
Operational Quantum Physics offers a systematic presentation of quantum mechanics which makes exhaustive use of the full probabilistic structure of this theory. Accordingly the notion of an observable as a positive operator valued (POV) measure is explained in great detail, and the ensuing quantum measurement theory is developed and applied both to a resolution of long-standing conceptual and interpretational puzzles in the foundations of quantum mechanics, and to an analysis of various recent fundamental experiments. The book, or different parts of it, may be of interest to advanced students or researchers in quantum physics, to philosophers of physics, and to mathematicians working in operator valued measures.

Author: Bikas K. Chakrabarti
Publisher: Springer Science & Business Media
ISBN: 3540498656
Category : Science
Languages : en
Pages : 217

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Book Description
Investigations into the zero-temperature phases in various frustrated and random Ising models in a transverse or tunnelling field have caught attention very recently in the context of quantum magnetisation of glasses and other frustrated systems. This book gives a detailed discussion of the various theoretical techniques developed for the study of transverse Ising models and of the results of these studies with regular and random frustration, dilution, randomness, etc. Recent developments in the studies on their (quantum) relaxational dynamics, such as in quantum hysteresis, are also treated. The detailed presentation of original results and the reviews given here are expected to inspire further research in the exciting field of quantum many-body systems with randomness and frustration.

Author: Hans-Jürgen Borchers
Publisher: Springer Science & Business Media
ISBN: 3540499547
Category : Science
Languages : en
Pages : 143

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Book Description
At the time I learned quantum field theory it was considered a folk theo rem that it is easy to construct field theories fulfilling either the locality or the spectrum condition. The construction of an example for the latter case is particularly easy. Take for instance an irreducible representation of the Poincare group with positive energy, and as an algebra of observables all compact operators in that representation space. This algebra of observables is even an asymptotically Abelian algebra. Since it has only a single repre sentation - except for multiples of this one - it is hardly possible to replace locality in order to obtain a theory with a reasonable physical structure. This example shows that it is not sufficient to replace locality by asymptotic Abelian-ness. The construction of a theory fulfilling locality without a pos itive energy representation was first done by Doplicher, Regge, and Singer [DRS]. However, modern investigations on the locality ideal in the algebra oftest functions, started by Alcantara and Yngvason [AY], seem to indicate that this is a general feature; this means that most of the algebras of ob servables fulfilling the locality condition will not have representations that also fulfil the spectrum condition. This discussion shows that quantum field theory becomes a subject of interest only if both conditions are satisfied at the same time.

Author: Barnabas Apagyi
Publisher: Springer
ISBN: 3662141450
Category : Science
Languages : en
Pages : 402

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Book Description
This volume contains three interrelated, beautiful, and useful topics of quantum scattering theory: inverse scattering theory, algebraic scattering theory and supersymmetrical quantum mechanics. The contributions cover such issues as coupled-channel inversions at fixed energy, inversion of pion-nucleon scattering cross-sections into potentials, inversions in neutron and x-ray reflection, 3-dimensional fixed-energy inversion, inversion of electron scattering data affected by dipole polarization, nucleon-nucleon potentials by inversion versus meson-exchange theory, potential reversal and reflectionless impurities in periodic structures, quantum design in spectral, scattering, and decay control, solution hierarchy of Toda lattices, etc.

Author: Ludwig Pittner
Publisher: Springer Science & Business Media
ISBN: 3540478019
Category : Science
Languages : en
Pages : 476

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Book Description
Quantum groups and quantum algebras as well as non-commutative differential geometry are important in mathematics and considered to be useful tools for model building in statistical and quantum physics. This book, addressing scientists and postgraduates, contains a detailed and rather complete presentation of the algebraic framework. Introductory chapters deal with background material such as Lie and Hopf superalgebras, Lie super-bialgebras, or formal power series. Great care was taken to present a reliable collection of formulae and to unify the notation, making this volume a useful work of reference for mathematicians and mathematical physicists.

Author: M. Dineykhan
Publisher: Springer Science & Business Media
ISBN: 3540491864
Category : Science
Languages : en
Pages : 281

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Book Description
The investigation ofmost problems of quantum physics leads to the solution of the Schrodinger equation with an appropriate interaction Hamiltonian or potential. However, the exact solutions are known for rather a restricted set of potentials, so that the standard eternal problem that faces us is to find the best effective approximation to the exact solution of the Schrodinger equation under consideration. In the most general form, this problem can be formulated as follows. Let a total Hamiltonian H describing a relativistic (quantum field theory) or a nonrelativistic (quantum mechanics) system be given. Our problem is to solve the Schrodinger equation Hlft = Enlftn, n i. e. , to find the energy spectrum {En} and the proper wave functions {lft } n including the'ground state or vacuum lft = 10). The main idea of any ap o proximation technique is to find a decomposition in such a way that Ha describes our physical system in the "closest to H" manner, and the Schrodinger equation HolJt. (O) = E(O)lJt. (O) n n n can be solved exactly. The interaction Hamiltonian HI is supposed to give small corrections to the zero approximation which can be calculated. In this book, we shall consider the problem of a strong coupling regime in quantum field theory, calculations ofpath or functional integrals over the Gaussian measure and spectral problems in quantum mechanics. Let us con sider these problems briefly.

Author: Mauro Ferrari
Publisher: Springer Science & Business Media
ISBN: 354049636X
Category : Science
Languages : en
Pages : 225

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Book Description
The recently proposed, fully multi-scale theory of doublet mechanics offers unprecented opportunities to reconcile the discrete and continuum representations of solids while maintaining a simple analytical format and full compatibility with lattice dynamics and continuum mechanics. In this monograph, a self-contained account of the state of the art in doublet mechanics is presented. Novel results in the elastodynamics of microstructured media are reported, including the identification of a new class of dispersive surface waves, and the presentation of methods for the experimental determination of the essential microstructural parameters. The relationships between doublet mechanics, lattice dynamics, and continuum theories are examined, leading to the identification of the subject areas in which the use of doublet mechanics is most advantageous. These areas include the analysis of domains as diverse as micro-electro-mechanical systems (MEMS), granular and particulate media, nanotubes, and peptide arrays.

Author: Alexander Bach
Publisher: Springer Science & Business Media
ISBN: 3540496246
Category : Science
Languages : en
Pages : 166

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Book Description
Here, the concept of indistinguishability is defined for identical particles by the symmetry of the state, therefore applying to both the classical and the quantum framework. The author describes symmetric statistical operators and classifies these by means of extreme points. He derives de Finettis theorem for the description of infinitely extendible interchangeable random variables, and presents generalisations covering the Poisson limit and the central limit. Finally, a characterisation and interpretation of the integral representations of classical photon states in quantum optics are derived in abelian subalgebras, and unextendible indistinguishable particles are analysed in the context of non-classical photon states. Suitable for mathematical physicists and philosophers of science.

Author: Pedro L. Garrido
Publisher: Springer
ISBN: 3662141485
Category : Science
Languages : en
Pages : 326

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Book Description
The methods developed to deal with the computational aspects of physi cal problems are useful in an increasing number of situations, from chem istry, biology and geology to engineering, communications and economics. In fact, computational physics has evolved into a trans-disciplinary field now concerned with the creative use of computers in scientific research. More over, computational methods often help students to develop a deeper under standing of key concepts, and enhance their problem-solving abilities. There fore, computational physics is recognized as having an important educational value, and educators face the task of outlining appropriate curricula to take advantage of these unique features. This is an important motivation for the publication of the contents of the Seminar on Computational Physics which is held in Granada every two years. The seminar aims at bringing together small groups of students and active researchers on different aspects of computational physics. It is part of the doctoral programme of the University of Granada. The proceedings of the previous editions were published as II Granada Lectures in Computational Physics (World Scientific, Singapore 1993) and Third Granada Lectures in Computational Physics (Lecture Notes in Physics, vol. 448, Springer, Berlin 1995) by the same editors. The present book contains the invited lecture notes and a very brief account of contributions by participants at the 4th Granada Seminar on Computational Physics (Granada, Spain, 9-14 September 1996).