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We establish a new approach to calculating spectral statistics in disordered conductors, by considering how energy levels move in response to changes in the impurity potential. We use this fictitious dynamics to calculate the spectral form…

Condensed Matter · Physics 2009-10-28 J. T. Chalker , Igor V. Lerner , Robert A. Smith

The existing research on spectral algorithms, applied within a Reproducing Kernel Hilbert Space (RKHS), has primarily focused on general kernel functions, often neglecting the inherent structure of the input feature space. Our paper…

Machine Learning · Statistics 2024-03-08 Weichun Xia , Lei Shi

The Wigner phase-space distribution function provides the basis for Moyal's deformation quantization alternative to the more conventional Hilbert space and path integral quantizations. General features of time-independent Wigner functions…

High Energy Physics - Theory · Physics 2009-10-02 Thomas Curtright , David Fairlie , Cosmas Zachos

Recent developments are (meta)reviewed in the applications of Wigner functions to describe the observed single particle spectra and two-particle Bose-Einstein (or Hanbury Brown -- Twiss) correlations in high energy particle and nuclear…

Quantum Physics · Physics 2009-11-10 T. Csorgo

This paper concerns spectral properties of linear Schr\"odinger operators under oscillatory high-amplitude potentials on bounded domains. Depending on the degree of disorder, we prove the existence of spectral gaps amongst the lowermost…

Numerical Analysis · Mathematics 2020-02-11 Robert Altmann , Patrick Henning , Daniel Peterseim

Using the notion of spectral flow, we suggest a simple approach to various asymptotic problems involving eigenvalues in the gaps of the essential spectrum of self-adjoint operators. Our approach uses some elements of the spectral shift…

Spectral Theory · Mathematics 2015-05-13 Alexander Pushnitski

Cluster perturbation theory in combination with the Lanczos method is used to compute the one-electron spectral function of the Holstein polaron in one and two dimensions. It is shown that the method allows reliable calculations using…

Strongly Correlated Electrons · Physics 2007-06-13 Martin Hohenadler , Markus Aichhorn , Wolfgang von der Linden

We review the Weyl-Wigner formulation of quantum mechanics in phase space. We discuss the concept of Narcowich-Wigner spectrum and use it to state necessary and sufficient conditions for a phase space function to be a Wigner distribution.…

High Energy Physics - Theory · Physics 2009-11-11 Nuno Costa Dias , Joao Nuno Prata

Neural networks represent more features than they have dimensions via superposition, forcing features to share representational space. Current methods decompose activations into sparse linear features but discard geometric structure. We…

Machine Learning · Computer Science 2026-02-03 Georgi Ivanov , Narmeen Oozeer , Shivam Raval , Tasana Pejovic , Shriyash Upadhyay , Amir Abdullah

Unsupervised semantic segmentation is a long-standing challenge in computer vision with great significance. Spectral clustering is a theoretically grounded solution to it where the spectral embeddings for pixels are computed to construct…

Computer Vision and Pattern Recognition · Computer Science 2023-04-07 Zhijie Deng , Yucen Luo

The Weyl-Wigner representation of quantum mechanics allows one to map the density operator in a function in phase space - the Wigner function - which acts like a probability distribution. In the context of statistical mechanics, this…

Quantum Physics · Physics 2023-08-31 Marcos Gil de Oliveira , Alfredo Miguel Ozorio de Almeida

We compute spectral function for $^4$He by combining coupled-cluster theory with an expansion of integral transforms into Chebyshev polynomials. Our method allows to estimate the uncertainty of spectral reconstruction. The properties of the…

Nuclear Theory · Physics 2024-02-16 J. E. Sobczyk , S. Bacca , G. Hagen , T. Papenbrock

As a continuation of our previous work \cite{KV2} the aim of the recent paper is to investigate the solutions of special inhomogeneous linear functional equations by using spectral synthesis in translation invariant closed linear subspaces…

Complex Variables · Mathematics 2017-04-18 Gergely Kiss , Csaba Vincze

Landscape functions are a popular tool used to provide upper bounds for eigenvectors of Schr\"odinger operators on domains. We review some known results obtained in the last ten years, unify several approaches used to achieve such bounds,…

Spectral Theory · Mathematics 2023-12-25 Delio Mugnolo

In this paper, we provide an approach for the calculation of one-loop effective actions, vacuum energies, and spectral counting functions and discuss the application of this approach in some physical problems. Concretely, we construct the…

High Energy Physics - Theory · Physics 2014-11-21 Wu-Sheng Dai , Mi Xie

In this article, we first introduce a singular fractional Sturm-Liouville eigen-problems (SFSLP) on unbounded domain. The associated fractional differential operators in these problems are both Weyl and Caputo type . The properties of…

Numerical Analysis · Mathematics 2015-02-20 T. Aboelenen , H. M. El-Hawary

In this paper, we give a new approach for the study of Weyl-type theorems. Precisely we introduce the concepts of spectral valued and spectral partitioning functions. Using two natural order relations on the set of spectral valued…

Spectral Theory · Mathematics 2013-04-12 Mohammed Berkani

We develop novel methods to compute auto-correlation functions, or power spectral densities, for chaotic dynamical systems generated by an inverse method whose starting point is an invariant distribution and a two-form. In general, the…

Chaotic Dynamics · Physics 2008-09-02 Gerald Guralnik , Zachary Guralnik , Cengiz Pehlevan

The theory of finite-rank perturbations allows for the determination of spectral information for broad classes of operators using the tools of analytic function theory. In this work, finite-rank perturbations are applied to powers of the…

Spectral Theory · Mathematics 2022-09-01 Michael Bush , Constanze Liaw , Robert T. W. Martin

In this paper, we design and analyze a novel spectral method for the subdiffusion equation. As it has been known, the solutions of this equation are usually singular near the initial time. Consequently, direct application of the traditional…

Numerical Analysis · Mathematics 2022-04-06 Chuanju Xu , Wei Zeng