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Previous results pertaining to algebraic state and parameter estimation of linear systems based on a special construction of a forward-backward kernel representation of linear differential invariants are extended to handle large noise in…

Systems and Control · Electrical Eng. & Systems 2021-02-02 Debarshi Patanjali Ghoshal , Hannah Michalska

The bidomain equations have been widely used to mathematically model the electrical activity of the cardiac tissue. In this work, we present a potential theory-based Cartesian grid method which is referred as the kernel-free boundary…

Numerical Analysis · Mathematics 2021-04-13 Xindan Gao , Li Cai , Craig S. Henriquez , Wenjun Ying

Two-color finite density QCD is free from the sign problem, and it is thus regarded as a good model to check the validity of the analytic continuation method. We study the method in terms of the corresponding chiral random matrix model. It…

High Energy Physics - Lattice · Physics 2009-03-06 Yasuhiko Shinno , Hiroshi Yoneyama

We present the multi-channel Dyson equation that combines two or more many-body Green's functions to describe the electronic structure of materials. In this work we use it to model photoemission spectra by coupling the one-body Green's…

Strongly Correlated Electrons · Physics 2023-10-03 Gabriele Riva , Pina Romaniello , J. Arjan Berger

Estimating the steady-state properties of open many-body quantum systems is a fundamental challenge in quantum science and technologies. In this work, we present a scalable approach based on semi-definite programming to derive certified…

The standard way to generate many-body quantum correlations is via a dynamical protocol: an initial product state is transformed by interactions that generate non-classical correlations at later times. Here, we show that many-body Bell…

Quantum Physics · Physics 2025-01-13 Marcin Płodzień , Jan Chwedeńczuk , Maciej Lewenstein

We develop a variational approach at finite temperature that incorporates many-body correlation self-consistently. The grand potential is constructed in terms of Green's function expressed by the variational parameters. We apply this…

Quantum Gases · Physics 2019-05-30 Akimitsu Kirikoshi , Wataru Kohno , Takafumi Kita

The rapid development in hardware for quantum computing and simulation has led to much interest in problems where these devices can exceed the capabilities of existing classical computers and known methods. Approaching this for problems…

Quantum Physics · Physics 2022-04-29 S. Flannigan , N. Pearson , G. H. Low , A. Buyskikh , I. Bloch , P. Zoller , M. Troyer , A. J. Daley

Accessing new regimes in quantum simulation requires the development of new techniques for quantum state preparation. We demonstrate the quantum state engineering of a strongly correlated many-body state of the two-component repulsive…

Quantum Gases · Physics 2018-06-20 Christie S. Chiu , Geoffrey Ji , Anton Mazurenko , Daniel Greif , Markus Greiner

A generalized stochastic method for projecting out the ground state of the quantum many-body Schr\"odinger equation on curved manifolds is introduced. This random-walk method is of wide applicability to any second order differential…

Statistical Mechanics · Physics 2007-05-23 V. Melik-Alaverdian , G. Ortiz , N. E. Bonesteel

We study the spectral statistics of quantum systems with finite Hilbert spaces. We derive a theorem showing that eigenlevels in such systems cannot be globally uncorrelated, even in the case of fully integrable dynamics, as a consequence of…

Statistical Mechanics · Physics 2021-01-14 Ángel L. Corps , Armando Relaño

We present a diagrammatic approach to construct self-energy approximations within many-body perturbation theory with positive spectral properties. The method cures the problem of negative spectral functions which arises from a…

Other Condensed Matter · Physics 2015-06-22 G. Stefanucci , Y. Pavlyukh , A. -M. Uimonen , R. van Leeuwen

We theoretically examine the finite-temperature spectral function of Fermi polarons in three dimensions, by using a self-consistent many-body $T$-matrix theory in real frequency. In comparison with the previous results from a…

Quantum Gases · Physics 2024-06-27 Hui Hu , Xia-Ji Liu

Within the non-equilibrium Green's function technique on the real time contour, the Phi-functional method of Baym is reviewed and generalized to arbitrary non-equilibrium many-particle systems. The scheme may be closed at any desired order…

High Energy Physics - Phenomenology · Physics 2008-11-26 Yu. B. Ivanov , J. Knoll , D. N. Voskresensky

We consider a general class of approximations which guarantees the conservation of particle number in many-body perturbation theory. To do this we extend the concept of $\Phi$-derivability for the self-energy $\Sigma$ to a larger class of…

Strongly Correlated Electrons · Physics 2016-09-15 Daniel Karlsson , Robert van Leeuwen

We introduce a general scheme to consistently truncate equations of motion for Green's functions. Our scheme is guaranteed to generate physical Green's functions with real excitation energies and positive spectral weights. There are free…

Strongly Correlated Electrons · Physics 2021-02-24 Francesco Catalano , Johan Nilsson

We present a highly parallelisable scheme for treating functional Renormalisation Group equations which incorporates a quasi-particle-based feedback on the flow and provides direct access to real-frequency self-energy data. This allows to…

Strongly Correlated Electrons · Physics 2020-12-09 D. Rohe , C. Honerkamp

We consider thermal $n$-point Green functions in the framework of quantum field theory at finite temperature. We show how analytic continuations from imaginary to real energies relate these functions originally defined in the imaginary-time…

High Energy Physics - Phenomenology · Physics 2014-11-17 R. Baier , A. Niegawa

A numerical bootstrap method is proposed to provide rigorous and nontrivial bounds in general quantum many-body systems with locality. In particular, lower bounds on ground state energies of local lattice systems are obtained by imposing…

Strongly Correlated Electrons · Physics 2020-09-16 Xizhi Han

Computation of the Green's function is crucial to study the properties of quantum many-body systems such as strongly correlated systems. Although the high-precision calculation of the Green's function is a notoriously challenging task on…