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It is well established that causal linear response functions can be found by computing the much simpler imaginary time-ordered Matsubara functions and performing an analytic continuation. This principle is the basis for much of our…

Mesoscale and Nanoscale Physics · Physics 2025-06-27 Sounak Sinha , Barry Bradlyn

Sequential experimental design to discover interventions that achieve a desired outcome is a key problem in various domains including science, engineering and public policy. When the space of possible interventions is large, making an…

Machine Learning · Computer Science 2023-08-17 Jiaqi Zhang , Louis Cammarata , Chandler Squires , Themistoklis P. Sapsis , Caroline Uhler

Causal effect estimation often succeeds cost-constrained sequential data collection. This work considers multivariate linear front-door models with arbitrary unobserved confounding on treatment and response. We optimize the experimental…

Methodology · Statistics 2026-03-24 Leopold Mareis , Mathias Drton

I review the quantum theory of the electron moving in a random environment. First, the quantum mechanics of individual particles scattered on a random potential is discussed. The quantum-mechanical description is extended to many-body…

Disordered Systems and Neural Networks · Physics 2021-09-13 Václav Janiš

The steady-state electronic transport across periodically driven systems can be efficiently addressed using Landauer-B\"{u}ttiker formalism. The time-dependent nonequilibrium Green's function theory then may be adapted for developing direct…

Mesoscale and Nanoscale Physics · Physics 2018-12-17 Oleksandr Balabanov

The interaction of electrons with quantized phonons and photons underlies the ultrafast dynamics of systems ranging from molecules to solids, and it gives rise to a plethora of physical phenomena experimentally accessible using…

Strongly Correlated Electrons · Physics 2021-07-21 Daniel Karlsson , Robert van Leeuwen , Yaroslav Pavlyukh , Enrico Perfetto , Gianluca Stefanucci

We introduce a performance-driven framework for constructing strictly causal forward-oriented observables in strongly non-stationary time series. The method combines a robustly normalized composite of heterogeneous indicators with a…

Computational Finance · Quantitative Finance 2026-03-17 Lucas A. Souza

Flexible boundary condition methods couple an isolated defect to bulk through the bulk lattice Green's function. The inversion of the force-constant matrix for the lattice Green's function requires Fourier techniques to project out the…

Materials Science · Physics 2010-05-28 M. Ghazisaeidi , D. R. Trinkle

Green's function methods within many-body perturbation theory provide a general framework for treating electronic correlations in excited states. Here we investigate the cumulant form of the one-electron Green's function based on the…

Chemical Physics · Physics 2021-04-23 F. D. Vila , J. J. Rehr , J. J. Kas , K. Kowalski , B. Peng

Due to random dopant fluctuations, the device-to-device variability is a serious challenge to emerging nanoelectronics. In this work we present theoretical formalisms and numerical simulations of quantum transport variability, based on the…

Mesoscale and Nanoscale Physics · Physics 2013-11-14 Yu Zhu , Lei Liu , Hong Guo

We study Green's function and the large time behavior of the one-dimensional Euler-Maxwell System with relaxation. Firstly, we construct the Green's function of linearized system and obtain the optimal time decay rates of its solutions. And…

Analysis of PDEs · Mathematics 2025-04-30 Boyu Liang , Mingying Zhong

General formula for causal Green's function of linear differential operator of given degree in one variable is given according to coefficient functions of differential operator as a series of integrals. The solution also provides analytic…

Classical Analysis and ODEs · Mathematics 2013-04-16 Adel Kassaian

The Brownian motion over the space of fluid velocity configurations driven by the hydrodynamical equations is considered. The Green function is computed in the form of an asymptotic series close to the standard diffusion kernel. The high…

Soft Condensed Matter · Physics 2007-05-23 D. Volchenkov , R. Lima

We propose a scheme for the construction of one-particle Green's function (GF) of an interacting electronic system via statistical sampling on a quantum computer. Although the non-unitarity of creation and annihilation operators for the…

Quantum Physics · Physics 2020-02-19 Taichi Kosugi , Yu-ichiro Matsushita

Identifying the causal structure of systems with multiple dynamic elements is critical to several scientific disciplines. The conventional approach is to conduct statistical tests of causality, for example with Granger Causality, between…

Machine Learning · Statistics 2022-03-22 Jacek P. Dmochowski

We present a data-driven approach to mathematically model physical systems whose governing partial differential equations are unknown, by learning their associated Green's function. The subject systems are observed by collecting…

Numerical Analysis · Mathematics 2023-03-13 Harshwardhan Praveen , Nicolas Boulle , Christopher Earls

We develop a reliable parameter-free analytic continuation method for quantum many-body calculations. Our method is based on a kernel grid, a causal spline, a regularization using the second-derivative roughness penalty, and the L-curve…

Strongly Correlated Electrons · Physics 2023-01-03 Mancheon Han , Hyoung Joon Choi

We propose functional causal Bayesian optimization (fCBO), a method for finding interventions that optimize a target variable in a known causal graph. fCBO extends the CBO family of methods to enable functional interventions, which set a…

Machine Learning · Statistics 2023-06-14 Limor Gultchin , Virginia Aglietti , Alexis Bellot , Silvia Chiappa

Artificial intelligence models and methods commonly lack causal interpretability. Despite the advancements in interpretable machine learning (IML) methods, they frequently assign importance to features which lack causal influence on the…

Machine Learning · Computer Science 2024-01-29 Francisco Nunes Ferreira Quialheiro Simoes , Mehdi Dastani , Thijs van Ommen

Several widely used methods for the calculation of band structures and photo emission spectra, such as the GW approximation, rely on Many-Body Perturbation Theory. They can be obtained by iterating a set of functional differential equations…

Strongly Correlated Electrons · Physics 2012-01-31 Giovanna Lani , Pina Romaniello , Lucia Reining