共查询到20条相似文献,搜索用时 15 毫秒
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Systems of strongly coupled chaotic maps generically exhibit collective behavior emerging out of extensive chaos. We show how the well-known renormalization group (RG) of unimodal maps can be extended to the coupled systems, and in particular to coupled map lattices (CMLs) with local diffusive coupling. The RG relation derived for CMLs is nonperturbative, i.e., not restricted to a particular class of configurations nor to some vanishingly small region of parameter space. After defining the strong-coupling limit in which the RG applies to almost all asymptotic solutions, we first present the simple case of coupled tent maps. We then turn to the general case of unimodal maps coupled by diffusive coupling operators satisfying basic properties, extending the formal approach developed by Collet and Eckmann for single maps. We finally discuss and illustrate the general consequences of the RG: CMLs are shown to share universal properties in the space-continuous limit which emerges naturally as the group is iterated. We prove that the scaling properly ties of the local map carry to the coupled systems, with an additional scaling factor of length scales implied by the synchronous updating of these dynamical systems. This explains various scaling laws and self-similar features previously observed numerically. 相似文献
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We study spectral properties of a system of weakly coupled stochastic evolutions placed at sites of a lattice. Under general assumptions we prove a simple criterion for the presence of spectral gaps and develop a scattering theory of quasi-particle excitations. 相似文献
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Aaraki Huzihiro Flato Moshé Michéa Sébastien Sternheimer Daniel 《Letters in Mathematical Physics》1998,43(2):155-171
We indicate similarities in the structure of two types of infinite-dimensional algebras, one introduced 28 years ago in connection with the mass problem of elementary particles and the other seven years ago in connection with spin systems (XY models). We show that these algebras can be considered as representations of a single Grand Algebra, the enveloping algebra of an affine Kac–Moody algebra built on the Poincaré Lie algebra. As an associative and coassociative bialgebra of operators, the latter representation of the grand algebra is a preferred nontrivial deformation of the Ising case bialgebra. 相似文献
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We study the dynamics of large polarons described by the Fröhlich Hamiltonian in the limit of strong coupling. The initial conditions are (perturbations of) product states of an electron wave function and a phonon coherent state, as suggested by Pekar. We show that, to leading order on the natural time scale of the problem, the phonon field is stationary and the electron moves according to an effective linear Schrödinger equation. 相似文献
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《Journal of Magnetic Resonance, Series A》1994,106(2):159-167
Optimized AM/FM pulses are described which excite an arbitrary coherence of a coupled spin system with optimal intensity. These pulses may become important for creating maximum signal intensity in MQC-filtered and polarization-transfer experiments in HRNMR and in vivo spectroscopy. For an AB system, for example, a pure DQC or ZQC state is obtained (100%) compared to maximal 50% with a conventional π/2-π/2 MQC pulse sequence. The design and numerical optimization of these pulses, with pulse times of about 1/2J (J is the coupling constant), are described. Examples of three of these spin-state-selective pulses (SSSP) for an AB system are given; simulations and experiments confirm their expected performance. To get some insight in the relations between the expectation values of the several coherences under the influence of Zeeman, J-coupling, and RF terms, Bloch-like equations for a proton AB system are derived, with neglection of relaxation. A system of 15 first-order coupled differential equations is found. A solution to these equations is given for the evolution of the zero-quantum coherence and longitudinal magnetization. 相似文献
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Robin Steinigeweg Heinz-Jürgen Schmidt 《Mathematical Physics, Analysis and Geometry》2009,12(1):19-45
We investigate certain classes of integrable classical or quantum spin systems. The first class is characterized by the recursively
defined property P saying that the spin system consists of a single spin or can be decomposed into two uniformly coupled or disjoint subsystems
with property P. For these systems the time evolution can be explicitly calculated. The second class consists of spin systems where all non-zero
coupling constants have the same strength (spin graphs) possessing N − 1 independent, commuting constants of motion of Heisenberg type. These systems are shown to have the above property P and can be characterized as spin graphs not containing chains of length four as vertex-induced sub-graphs. We completely
enumerate and characterize all spin graphs up to N = 5 spins. Applications to the construction of symplectic numerical integrators for non-integrable spin systems are briefly
discussed.
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Large Deviations for Quantum Spin Systems 总被引:1,自引:0,他引:1
We consider high temperature KMS states for quantum spin systems on a lattice. We prove a large deviation principle for the distribution of empirical averages
, where the X
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's are copies of a self-adjoint element X (level one large deviations). From the analyticity of the generating function, we obtain the central limit theorem. We generalize to a level two large deviation principle for the distribution of
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We analyze the collective excitations in two‐ and three‐dimensional binary Yukawa systems, consisting of two components with different masses. Theoretical analysis reveals a profound difference between the weakly and strongly correlated limits: at weak coupling the two components interact via the mean field only and the oscillation frequency is governed by the light component. In the strongly correlated limit the mode frequency is governed by the combined mass, where the heavy component dominates. Computer simulations in the full coupling range extend and confirm the theoretical results (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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In present work the formation of dusty plasma structures in cryogenic glow dc discharge was investigated. The ordered structures from large number (~104) of charged diamagnetic dust particles in a cusp magnetic trap have been also studied in microgravity conditions. The super high charging (up to 5·107e) of dust macroparticles under direct stimulation by an electron beam is experimentally performed and investigated. The results of the investigation of Brownian motion for strongly coupled dust particles in plasma are presented. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Schulz HJ 《Physical review letters》1996,77(13):2790-2793
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《中国物理快报》2016,(10)
We present the experimental results of nitrogen-vacancy(NV) electron spin decoherence,which are linked to the coexistence of electron spin bath of nitrogen impurity(P1 center) and ~(13)C nuclear spin bath.In previous works,only one dominant decoherence source is studied:PI electron spin bath for type-lb diamond;or ~(13)C nuclear spin bath for type-Ⅱa diamond.In general,the thermal fluctuation from both spin baths can be eliminated by the Hahn echo sequence,resulting in a long coherence time(T_2) of about 400 μs.However,in a high-purity type-Ⅱa diamond where ~(13)C nuclear spin bath is the dominant decoherence source,dramatic decreases of NV electron spin T_2 time caused by P1 electron spin bath are observed under certain magnetic field.We further apply the engineered Hahn echo sequence to confirm the decoherence mechanism of multiple spin baths and quantitatively estimate the contribution of P1 electron spin bath.Our results are helpful to understand the NV decoherence mechanisms,which will benefit quantum computing and quantum metrology. 相似文献
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We investigate the low-noise regime of a large class of probabilistic cellular automata, including the North-East-Center model of Toom. They are defined as stochastic perturbations of cellular automata belonging to the category of monotonic binary tessellations and possessing a property of erosion. We prove, for a set of initial conditions, exponential convergence of the induced processes toward an extremal invariant measure with a highly predominant spin value. We also show that this invariant measure presents exponential decay of correlations in space and in time and is therefore strongly mixing. 相似文献
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《Journal of Nonlinear Mathematical Physics》2013,20(3):376-398
Abstract The set of systems of differential equations that are in normal form with respect to a particular linear part has the structure of a module of equivariants, and is best described by giving a Stanley decomposition of that module. In this paper Groebner basis methods are used to determine a Groebner basis for the ideal of relations and a Stanley decomposition for the ring of invariants that arise in normal forms for Takens-Bogdanov systems. An algorithm developed by Murdock, is then used to produce a Stanley decomposition for the (normal form module) module of the equivariants from the Stanley decomposition for the ring of invariants. 相似文献
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Jinwen Chen 《Journal of statistical physics》1998,91(1-2):369-393
In this paper we investigate the large deviation principle (LDP) for spin particle systems with possibly vanishing flip rates. The situation turns out to be much more complicated if the flip rates are allowed to be zero than the one considered by Dai, where the systems are assumed to have strictly positive flip rates. The upper and lower large-deviation bounds are studied, respectively. The two governing rate functions are compared and a variational principle is given. We then apply the results to obtain some new large-deviation estimates for the occupation times of attractive systems. In particular, we prove a strong form of exponential convergence for ergodic systems. 相似文献