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Quantized tensor trains (QTTs) are a multiscale computational framework that can potentially reduce the computational cost of solving partial differential equations and initial value problems by making low-rank approximations. However, its…

Computational Physics · Physics 2026-05-14 Erika Ye

The nonequilibrium Green's function (NEGF) formalism is a powerful tool to study the nonequilibrium dynamics of correlated lattice systems, but its applicability to realistic system sizes and long timescales is limited by unfavorable memory…

Strongly Correlated Electrons · Physics 2025-09-29 Maksymilian Środa , Ken Inayoshi , Michael Schüler , Hiroshi Shinaoka , Philipp Werner

We present an algorithm to compute Green's functions on quantum computers for interacting electron systems, which is a challenging task on conventional computers. It uses a continued fraction representation based on the Lanczos method,…

Quantum Physics · Physics 2022-12-07 Francois Jamet , Abhishek Agarwal , Ivan Rungger

We extend the formalism of the thermodynamic two-time Green's functions to nonextensive quantum statistical mechanics. Working in the optimal Lagrangian multipliers representation, the $q$-spectral properties and the methods for a direct…

Statistical Mechanics · Physics 2008-09-07 A. Cavallo , F. Cosenza , L. De Cesare

We present an elementary nonperturbative method to obtain Green's functions (GFs) for timelike momenta. We assume there are no singularities in the first and third quadrants of the complex plane of space momentum components and perform a 3d…

High Energy Physics - Phenomenology · Physics 2009-02-02 V. Sauli , Z. Batiz

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

Non-equilibrium Green's function theory for non-adiabatic effects in quantum transport [Kershaw and Kosov, J.Chem. Phys. 2017, 147, 224109 and J. Chem. Phys. 2018, 149, 044121] is extended to the case of interacting electrons. We consider a…

Mesoscale and Nanoscale Physics · Physics 2019-02-20 Vincent F. Kershaw , Daniel S. Kosov

In the path integral formulation of the evolution of an open quantum system coupled to a Gaussian, non-interacting environment, the dynamical contribution of the latter is encoded in an object called the influence functional. Here, we…

Quantum Physics · Physics 2019-12-16 Mathias R. Jørgensen , Felix A. Pollock

We propose a general framework for computing Retarded Green's Functions (RGFs) on quantum computers by recasting their evaluation as a problem of circuit differentiation. Our proposal is based on real-time evolution and specifically…

Quantum Physics · Physics 2026-04-15 Samuele Piccinelli , Francesco Tacchino , Ivano Tavernelli , Giuseppe Carleo

Accurate computation of the Green's function is crucial for connecting experimental observations to the underlying quantum states. A major challenge in evaluating the Green's function in the time domain lies in the efficient simulation of…

Quantum Physics · Physics 2025-09-12 Lingyun Wan , Jie Liu , Jinlong Yang

The non-equilibrium Green's function method combined with density functional theory (NEGF-DFT) provides a rigorous framework for simulating nanoscale electronic transport, but its computational cost scales steeply with system size. Recent…

Mesoscale and Nanoscale Physics · Physics 2025-10-21 Zili Tang , Xiaoxin Xie , Guanwen Yao , Ligong Zhang , Xiaoyan Liu , Xing Zhang , Liu Fei

This review is devoted to the different techniques that have been developed to compute the phase-coherent transport properties of quantum nanoelectronic systems connected to electrodes. Beside a review of the different algorithms proposed…

We show that cluster algorithms for quantum models have a meaning independent of the basis chosen to construct them. Using this idea, we propose a new method for measuring with little effort a whole class of Green's functions, once a…

Statistical Mechanics · Physics 2015-06-25 R. Brower , S. Chandrasekharan , U. -J. Wiese

We propose an improved quantum algorithm to calculate the Green's function through real-time propagation, and use it to compute the retarded Green's function for the 2-, 3- and 4-site Hubbard models. This novel protocol significantly…

Quantum Physics · Physics 2022-10-21 Francesco Libbi , Jacopo Rizzo , Francesco Tacchino , Nicola Marzari , Ivano Tavernelli

We establish quantitative Green's function estimates for a class of quasi-periodic (QP) operators on $\mathbb{Z}^d$ with certain slowly decaying long-range hopping and analytic cosine type potentials. As applications, we prove the…

Mathematical Physics · Physics 2025-07-30 Li Wen , Yuan Wu

Modern machine learning (ML) methods typically fail to adequately capture causal information. Consequently, such models do not handle data distributional shifts, are vulnerable to adversarial examples, and often learn spurious correlations.…

Quantum Physics · Physics 2026-01-27 Rishi Goel , Casey R. Myers , Sally Shrapnel

Simulating nonlinear classical dynamics on a quantum computer is an inherently challenging task due to the linear operator formulation of quantum mechanics. In this work, we provide a systematic approach to alleviate this difficulty by…

We present quantum electron transport theory that incorporates dynamical effects of motion of atoms on electrode-molecule interfaces in the calculations of the electric current. The theory is based on non-equilibrium Green's functions. We…

Mesoscale and Nanoscale Physics · Physics 2018-08-14 Vincent F. Kershaw , Daniel S. Kosov

The pair distribution function (PDF) is a key quantity for the analysis of correlation effects of a quantum system both in equilibrium and far from equilibrium. We derive an expression for the PDF in terms of the single-particle Green's…

Strongly Correlated Electrons · Physics 2013-09-19 M. Bonitz , S. Hermanns , K. Kobusch , K. Balzer

High-order derivatives of Green's functions are a key ingredient in Taylor-based fast multipole methods, Barnes-Hut $n$-body algorithms, and quadrature by expansion (QBX). In these settings, derivatives underpin either the formation,…

Computational Engineering, Finance, and Science · Computer Science 2026-04-01 Hirish Chandrasekaran , Andreas Kloeckner