160 research outputs found
Quantum Analysis and Nonequilibrium Response
The quantum derivatives of and , which play a basic
role in quantum statistical physics, are derived and their convergence is
proven for an unbounded positive operator in a Hilbert space. Using the
quantum analysis based on these quantum derivatives, a basic equation for the
entropy operator in nonequilibrium systems is derived, and Zubarev's theory is
extended to infinite order with respect to a perturbation. Using the
first-order term of this general perturbational expansion of the entropy
operator, Kubo's linear response is rederived and expressed in terms of the
inner derivation for the relevant Hamiltonian .
Some remarks on the conductivity are given.Comment: Latex, 16 pages, no figures, to be published in Prog. Theor. Phys.
(1998
General Formulation of Quantum Analysis
A general formulation of noncommutative or quantum derivatives for operators
in a Banach space is given on the basis of the Leibniz rule, irrespective of
their explicit representations such as the G\^ateaux derivative or commutators.
This yields a unified formulation of quantum analysis, namely the invariance of
quantum derivatives, which are expressed by multiple integrals of ordinary
higher derivatives with hyperoperator variables. Multivariate quantum analysis
is also formulated in the present unified scheme by introducing a partial inner
derivation and a rearrangement formula. Operator Taylor expansion formulas are
also given by introducing the two hyperoperators and with the inner derivation .
Physically the present noncommutative derivatives express quantum fluctuations
and responses.Comment: Latex file, 29 pages, no figur
Quantum Statistical Mechanics of Ideal Gas Obeying Fractional Exclusion Statistics: A Systematic Study
The quantum statistical mechanics of an ideal gas with a general
free-particle energy obeying fractional exclusion statistics are systematically
investigated in arbitrary dimensions. The pressure relations, the relation
between pressure and internal energy, the equation of state, as well as the
thermodynamic properties are thoroughly discussed. Some novel results are
obtained.Comment: Revtex, one figure in EPS format include
Determining equations for higher-order decompositions of exponential operators
The general decomposition theory of exponential operators is briefly
reviewed. A general scheme to construct independent determining equations for
the relevant decomposition parameters is proposed using Lyndon words. Explicit
formulas of the coefficients are derived.Comment: 30 page
Statistical Mechanics of Non-Equilibrium Systems : Extensive Property, Fluctuation and Nonlinear Response
この論文は国立情報学研究所の電子図書館事業により電子化されました
New Types of Phase Transitions in Magnetic Materials
The present paper reviews the recent work on the quantum effective-field theory by M.Suzuki (in Physica B, 1994). This new theory is shown to be very useful in studying new types of phase transitions in strongly correlated systems and in quantum magnetic systems
Towards Bose-Einstein Condensation of Electron Pairs: Role of Schwinger Bosons
It can be shown that the bosonic degree of freedom of the tightly bound
on-site electron pairs could be separated as Schwinger bosons. This is
implemented by projecting the whole Hilbert space into the Hilbert subspace
spanned by states of two kinds of Schwinger bosons (to be called binon and
vacanon) subject to a constraint that these two kinds of bosonic quasiparticles
cannot occupy the same site. We argue that a binon is actually a kind of
quantum fluctuations of electron pairs, and a vacanon corresponds to a vacant
state. These two bosonic quasiparticles may be responsible for the
Bose-Einstein condensation (BEC) of the system associated with electron pairs.
These concepts are also applied to the attractive Hubbard model with strong
coupling, showing that it is quite useful. The relevance of the present
arguments to the existing theories associated with the BEC of electron pairs is
briefly commented.Comment: Revtex, one figur
Parametric Wind Velocity Vector Estimation Method for Single Doppler LIDAR Model
Doppler lidar (LIght Detection And Ranging) can provide accurate wind velocity vector estimates by processing the time delay and Doppler spectrum of received signals. This system is essential for real-time wind monitoring to assist aircraft taking off and landing. Considering the difficulty of calibration and cost, a single Doppler lidar model is more attractive and practical than a multiple lidar model. In general, it is impossible to estimate two or three dimensional wind vectors from a single lidar model without any prior information, because lidar directly observes only a 1-dimensional (radial direction) velocity component of wind. Although the conventional VAD (Velocity Azimuth Display) and VVP (Velocity Volume Processing) methods have been developed for single lidar model, both of them are inaccurate in the presence of local air turbulence. This paper proposes an accurate wind velocity estimation method based on a parametric approach using typical turbulence models such as tornado, micro-burst and gust front. The results from numerical simulation demonstrate that the proposed method remarkably enhances the accuracy for wind velocity estimation in the assumed modeled turbulence cases, compared with that obtained by the VAD or other conventional method
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