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We apply a computationally efficient approach to study the time- and energy-resolved spectral properties of a two-site Hubbard model using the nonequilibrium Green's function formalism. By employing the iterative generalized Kadanoff-Baym…

Strongly Correlated Electrons · Physics 2025-06-04 Yaroslav Pavlyukh , Riku Tuovinen

We investigate the spectral properties of an open interacting system by solving the Generalized Kadanoff-Baym Ansatz (GKBA) master equation for the single-particle density matrix, namely the time-diagonal lesser Green's function. To…

Strongly Correlated Electrons · Physics 2020-07-20 F. Cosco , N. W. Talarico , R. Tuovinen , N. Lo Gullo

We review one of the most versatile theoretical approaches to the study of time-dependent correlated quantum transport in nano-systems: the non-equilibrium Green's function (NEGF) formalism. Within this formalism, one can treat, on the same…

Mesoscale and Nanoscale Physics · Physics 2022-06-27 M. Ridley , N. W. Talarico , D. Karlsson , N. Lo Gullo , R. Tuovinen

For a minimal Hubbard-type system at different interaction strengths U, we investigate the density-response for an excitation beyond the linear regime using the generalized Kadanoff-Baym ansatz (GKBA) and the second Born (2B) approximation.…

Strongly Correlated Electrons · Physics 2015-06-12 K. Balzer , S. Hermanns , M. Bonitz

Theory of non-equilibrium Green's function (NGF) provides a practical framework for studying quantum many-body systems out of equilibrium. Extending the previous mean field approach developed for nuclear systems in one dimension with NGF,…

Nuclear Theory · Physics 2020-08-26 Hao Lin , Hossein Mahzoon , Arnau Rios , Pawel Danielewicz

Simulations of interacting electrons and bosons out of equilibrium, starting from first principles and aiming at realistic multiscale scenarios, is a grand theoretical challenge. Here, using the formalism of nonequilibrium Green's functions…

Strongly Correlated Electrons · Physics 2022-04-06 Yaroslav Pavlyukh , Enrico Perfetto , Daniel Karlsson , Robert van Leeuwen , Gianluca Stefanucci

A nonequilibrium Green's functions (NEGF) approach for spatially inhomogeneous, strongly correlated artificial atoms is presented and applied to compute the time-dependent properties while starting from a (correlated) initial few-electron…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 K Balzer , M Bonitz

Understanding time-resolved quantum transport is crucial for developing next-generation quantum technologies, particularly in nano- and molecular junctions subjected to time-dependent perturbations. Traditional steady-state approaches to…

Mesoscale and Nanoscale Physics · Physics 2025-10-16 R. Tuovinen , Y. Pavlyukh

The HF-GKBA offers an approximate numerical procedure for propagating the two-time non-equilibrium Green's function(NEGF). Here we compare the HF-GKBA to exact results for a variety of systems with long and short-range interactions,…

Computational Physics · Physics 2023-02-15 Cian C. Reeves , Jia Yin , Yuanran Zhu , Khaled Z. Ibrahim , Chao Yang , Vojtech Vlcek

Nonequilibrium heat transport in quantum systems coupled to wide-band embeddings provides a striking example of the limitations of the generalized Kadanoff-Baym ansatz (GKBA), while solving the full two-time Kadanoff-Baym equations remains…

Mesoscale and Nanoscale Physics · Physics 2025-02-10 Yaroslav Pavlyukh , Riku Tuovinen

The Non-equilibrium Green's function (NEGF) formalism is a particularly powerful method to simulate the quantum transport properties of nanoscale devices such as transistors, photo-diodes, or memory cells, in the ballistic limit of…

We introduce diagrammatic technique for Hubbard nonequilibrium Green functions (NEGF). The formulation is an extension of equilibrium considerations for strongly correlated lattice models to description of current carrying molecular…

Mesoscale and Nanoscale Physics · Physics 2016-11-04 Feng Chen , Maicol A. Ochoa , Michael Galperin

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 context of a broad class of quenched models, we derive a generalized differential form of the Kadanoff-Baym (KB) ansatz which relates the out of equilibrium correlated and spectral Green's functions. This relation holds at any time…

High Energy Physics - Theory · Physics 2016-05-25 A. L. M. Britto , Ashok K. Das , J. Frenkel

A generalized quantum kinetic equation (RKE) of the Kadanoff-Baym type is obtained on the basis of the Heisenberg equations of motion where the time evolution and space translation are separated from each other by means of the covariant…

High Energy Physics - Phenomenology · Physics 2009-10-31 S. A. Smolyansky , A. V. Prozorkevich , G. Maino , S. G. Mashnik

We investigate out-of-equilibrium dynamics in an excitonic insulator (EI) with a finite momentum pairing perturbed by a laser-pulse excitation and a sudden coupling to fermionic baths. The transient dynamics of the excitonic order parameter…

Strongly Correlated Electrons · Physics 2020-09-29 Riku Tuovinen , Denis Golež , Martin Eckstein , Michael A. Sentef

We propose a time-dependent many-body approach to study the short-time dynamics of correlated electrons in quantum transport through nanoscale systems contacted to metallic leads. This approach is based on the time-propagation of the…

Mesoscale and Nanoscale Physics · Physics 2011-11-28 Petri Myohanen , Adrian Stan , Gianluca Stefanucci , Robert van Leeuwen

The Non-Equilibrium Green Function (NEGF) method was established in the 1960's through the classic work of Schwinger, Kadanoff, Baym, Keldysh and others using many-body perturbation theory (MBPT) and the diagrammatic theory for…

Mesoscale and Nanoscale Physics · Physics 2022-11-24 Kerem Y. Camsari , Shuvro Chowdhury , Supriyo Datta

A nonequilibrium Green's functions approach to the collective response of correlated Coulomb systems at finite temperature is presented. It is shown that solving Kadanoff-Baym type equations of motion for the two-time correlation functions…

Strongly Correlated Electrons · Physics 2009-02-11 N. -H. Kwong , M. Bonitz

We employ Non-equilibrium Green's functions (NEGF) to describe the real-time dynamics of an adsorbate-surface model system exposed to ultrafast laser pulses. For a finite number of electronic orbitals, the system is solved exactly and…

Mesoscale and Nanoscale Physics · Physics 2016-05-04 E. Boström , M. Hopjan , A. Kartsev , C. Verdozzi , C. -O. Almbladh