Results 21 to 30 of about 2,915 (59)
On Convergence of Extended Dynamic Mode Decomposition to the Koopman Operator
, 2017 Extended Dynamic Mode Decomposition (EDMD) is an algorithm that approximates the action of the Koopman operator on an $N$-dimensional subspace of the space of observables by sampling at $M$ points in the state space.
Korda, Milan, Mezić, Igor
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Double Copy From Tensor Products of Metric BV■‐Algebras
Fortschritte der Physik, Volume 73, Issue 1-2, February 2025.Abstract Field theories with kinematic Lie algebras, such as field theories featuring color–kinematics duality, possess an underlying algebraic structure known as BV■‐algebra. If, additionally, matter fields are present, this structure is supplemented by a module for the BV■‐algebra.
Leron Borsten +5 more
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Mathematical Methods in the Applied Sciences, Volume 48, Issue 2, Page 2267-2293, 30 January 2025.We study the Helmholtz equation with periodic coefficients in a closed waveguide. A functional analytic approach is used to formulate and solve the radiation problem in a self‐contained exposition. In this context, we simplify the non‐degeneracy assumption on the frequency.
A. Kirsch, B. Schweizer
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Iterative Deterministic Equivalents for the Performance Analysis of Communication Systems [PDF]
, 2011 In this article, we introduce iterative deterministic equivalents as a novel technique for the performance analysis of communication systems whose channels are modeled by complex combinations of independent random matrices.
Couillet, Romain +2 more
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Reflection Positivity and Conformal Symmetry
, 2013 The concept of reflection positivity has its origins in the work of Osterwalder--Schrader on constructive quantum field theory and duality between unitary representations of the euclidean motion group and the Poincare group.
Neeb, Karl-Hermann, Olafsson, Gestur
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Journal of the London Mathematical Society, Volume 110, Issue 5, November 2024.Abstract The aim of this paper is to prove the existence of Hadamard states for the Maxwell equations on any globally hyperbolic spacetime. This will be achieved by introducing a new gauge fixing condition, the Cauchy radiation gauge, that will allow to suppress all the unphysical degrees of freedom. The key ingredient for achieving this gauge is a new
Simone Murro, Gabriel Schmid
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Dissipative Dynamics of Quantum Fluctuations
, 2015 One way to look for complex behaviours in many-body quantum systems is to let the number $N$ of degrees of freedom become large and focus upon collective observables.
Alicki +13 more
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Accelerating Nonequilibrium Green Functions Simulations: The G1–G2 Scheme and Beyond
physica status solidi (b), Volume 261, Issue 9, September 2024.This article reviews recent developments in the theory of nonequilibrium Green functions (NEGF) where dramatic accelerations are achieved within the time‐local G1–G2 scheme. As a result, longer simulations with more accurate selfenergies are possible. The figure shows an illustration ‐ optical excitation of graphene by a short laser pulse: snapshot of ...
Michael Bonitz +5 more
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Low dimensional manifolds for exact representation of open quantum systems
, 2017 Weakly nonlinear degrees of freedom in dissipative quantum systems tend to localize near manifolds of quasi-classical states. We present a family of analytical and computational methods for deriving optimal unitary model transformations based on ...
Amini, Nina Hadis +2 more
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Local Whittle estimation with (quasi‐)analytic wavelets
Journal of Time Series Analysis, Volume 45, Issue 3, Page 421-443, May 2024.In the general setting of long‐memory multivariate time series, the long‐memory characteristics are defined by two components. The long‐memory parameters describe the autocorrelation of each time series. And the long‐run covariance measures the coupling between time series, with general phase parameters.
Sophie Achard, Irène Gannaz
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