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Continuously monitored quantum systems are emerging as promising platforms for quantum metrology, where a central challenge is to identify measurement strategies that optimally extract information about unknown parameters encoded in the…

Quantum Physics · Physics 2026-02-11 Alejandro Vivas-Viaña , Carlos Sánchez Muñoz

While Spectral Methods have long been used for Principal Component Analysis, this survey focusses on work over the last 15 years with three salient features: (i) Spectral methods are useful not only for numerical problems, but also discrete…

Data Structures and Algorithms · Computer Science 2010-04-09 Ravindran Kannan

We report multipronged progress on the stochastic averaging approach to numerical analytic continuation of quantum Monte Carlo data. With the sampled spectrum parametrized with delta-functions in continuous frequency space, a calculation of…

Strongly Correlated Electrons · Physics 2023-01-11 Hui Shao , Anders W. Sandvik

We construct non-random bounded discrete half-line Schr\" odinger operators which have purely singular continuous spectral measures with fractional Hausdorff dimension (in some interval of energies). To do this we use suitable sparse…

Mathematical Physics · Physics 2007-05-23 Andrej Zlatos

We study fractal dimension properties of singular Jacobi operators. We prove quantitative lower spectral/quantum dynamical bounds for general operators with strong repetition properties and controlled singularities. For analytic…

Spectral Theory · Mathematics 2018-04-24 Rui Han , Fan Yang , Shiwen Zhang

We introduce a framework for subspace methods which approximate the spectra of self-adjoint, unbounded operators in a local region. Using the projection-valued measure, we derive integrated spectral inequalities that also apply to unbounded…

Numerical Analysis · Mathematics 2026-01-06 Timothy Stroschein

We introduce a novel solver to significantly reduce the size of a geometric operator while preserving its spectral properties at the lowest frequencies. We use chordal decomposition to formulate a convex optimization problem which allows…

Graphics · Computer Science 2020-09-16 Honglin Chen , Hsueh-Ti Derek Liu , Alec Jacobson , David I. W. Levin

This paper addresses the problem of computing the eigenvalues lying in the gaps of the essential spectrum of a periodic Schrodinger operator perturbed by a fast decreasing potential. We use a recently developed technique, the so called…

Spectral Theory · Mathematics 2009-11-13 Lyonell Boulton , Michael Levitin

We consider the problem of designing an optimal quantum detector to minimize the probability of a detection error when distinguishing between a collection of quantum states, represented by a set of density operators. We show that the design…

Quantum Physics · Physics 2016-11-18 Yonina C. Eldar , Alexandre Megretski , George C. Verghese

We study multi-frequency quasiperiodic Schr\"{o}dinger operators on $\mathbb{Z} $. We prove that for a large real analytic potential satisfying certain restrictions the spectrum consists of a single interval. The result is a consequence of…

Spectral Theory · Mathematics 2017-09-01 Michael Goldstein , Wilhelm Schlag , Mircea Voda

We introduce a notion of $\beta$-almost periodicity and prove quantitative lower spectral/quantum dynamical bounds for general bounded $\beta$-almost periodic potentials. Applications include a sharp arithmetic criterion of full spectral…

Spectral Theory · Mathematics 2015-11-03 Svetlana Jitomirskaya , Shiwen Zhang

In this paper, we present an approach for explicitly constructing quasi-periodic Schr\"odinger operators with Cantor spectrum with $C^k$ potential. Additionally, we provide polynomial asymptotics on the size of spectral gaps.

Spectral Theory · Mathematics 2023-08-10 Jiawei He , Hongyu Cheng

The approximation of the eigenvalues and eigenfunctions of an elliptic operator is a key computational task in many areas of applied mathematics and computational physics. An important case, especially in quantum physics, is the computation…

Numerical Analysis · Mathematics 2018-08-31 Douglas Arnold , Guy David , Marcel Filoche , David Jerison , Svitlana Mayboroda

We study the convergence of two of the most widely used and intuitive approaches for computing the spectra of differential operators with quasiperiodic coefficients: the supercell method and the superspace method. In both cases,…

Spectral Theory · Mathematics 2024-11-26 Bryn Davies , Clemens Thalhammer

This paper establishes several sharp spectral results for analytic quasiperiodic Schrodinger operators. Key contributions include: (1) exact exponential decay rates for spectral gaps of the almost Mathieu operator, addressing a question…

Dynamical Systems · Mathematics 2025-11-25 Lingrui Ge , Jiangong You , Qi Zhou

We consider discrete one-dimensional Schr\"odinger operators on the whole line and establish a criterion for continuity of spectral measures with respect to $\log$-Hausdorff measures. We apply this result to operators with Sturmian…

Mathematical Physics · Physics 2014-12-31 David Damanik , Michael Landrigan

We consider discrete one-dimensional Schr\"odinger operators with strictly ergodic, aperiodic potentials taking finitely many values. The well-known tendency of these operators to have purely singular continuous spectrum of zero Lebesgue…

Spectral Theory · Mathematics 2007-05-23 David Damanik , Daniel Lenz

We develop an algebraic approach to studying the spectral properties of the stationary Schr\"odinger equation in one dimension based on its high order conditional symmetries. This approach makes it possible to obtain in explicit form…

High Energy Physics - Theory · Physics 2009-10-30 R. Z. Zhdanov

Quasiperiodic systems are important space-filling ordered structures, without decay and translational invariance. How to solve quasiperiodic systems accurately and efficiently is of great challenge. A useful approach, the projection method…

Numerical Analysis · Mathematics 2024-01-18 Kai Jiang , ShiFeng Li , Pingwen Zhang

The problem of quantum state preparation is one of the main challenges in achieving the quantum advantage. Furthermore, classically, for multi-level problems, our ability to solve the corresponding quantum optimal control problems is rather…