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We perform a perturbative analysis for the nonequilibrium Green functions of the spinless Falicov-Kimball model in the presence of an arbitrary external time-dependent but spatially uniform electric field. The conduction electron…

Strongly Correlated Electrons · Physics 2009-11-11 V. Turkowski , J. K. Freericks

Schwinger Keldysh field theory is a widely used paradigm to study non-equilibrium dynamics of quantum many-body systems starting from a thermal state. We extend this formalism to describe non-equilibrium dynamics of quantum systems starting…

Statistical Mechanics · Physics 2019-03-13 Ahana Chakraborty , Pranay Gorantla , Rajdeep Sensarma

We employ the influence functional technique to trace out the photonic contribution from full quantum electrodynamics. The reduced density matrix propagator for the spinor field is then constructed. We discuss the role of time-dependent…

High Energy Physics - Theory · Physics 2009-10-30 C. Anastopoulos , A. Zoupas

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

The self-energy functional theory (SFT) is generalized to describe the real-time dynamics of correlated lattice-fermion models far from thermal equilibrium. This is achieved by means of a reformulation of the original equilibrium theory in…

Strongly Correlated Electrons · Physics 2013-10-21 Felix Hofmann , Martin Eckstein , Enrico Arrigoni , Michael Potthoff

In this paper we review the partitioned and partition-free approaches to the calculation of the time-dependent response of a molecular junction to the switch-on of an arbitrary time-dependent bias. Using the non equilibrium Green's function…

Mesoscale and Nanoscale Physics · Physics 2018-04-04 Michael Ridley , Riku Tuovinen

We present a path-integral bosonization approach for systems out of equilibrium based on a duality transformation of the original Dirac fermion theory combined with the Schwinger-Keldysh time closed contour technique, to handle the…

High Energy Physics - Theory · Physics 2015-06-22 R. E. Gamboa Saraví , C. M. Naón , F. A. Schaposnik

This review deals with the nonequilibrium Green's function (NEGF) method applied to the problems of energy transport due to atomic vibrations (phonons), primarily for small junction systems. We present a pedagogical introduction to the…

Mesoscale and Nanoscale Physics · Physics 2013-05-28 Jian-Sheng Wang , Bijay Kumar Agarwalla , Huanan Li , Juzar Thingna

We address the existence of steady state Green-Keldysh correlation functions of interacting fermions in mesoscopic systems for both the partitioning and partition-free scenarios. Under some spectral assumptions on the non-interacting model…

Mathematical Physics · Physics 2015-06-16 Horia D. Cornean , Claude-Alain Pillet , Valeriu Moldoveanu

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

We provide a mathematically rigorous Keldysh functional integral for fermionic quantum field theories. We show convergence of a discrete-time Grassmann Gaussian integral representation in the time-continuum limit under very general…

Mathematical Physics · Physics 2025-08-05 Philipp Benjamin Aretz , Manfred Salmhofer

The time evolution of a finite fermion system towards statistical equilibrium is investigated using analytical solutions of a nonlinear partial differential equation that had been derived earlier from the Boltzmann collision term. The…

Statistical Mechanics · Physics 2018-12-07 T. Bartsch , G. Wolschin

Persistent currents circulate continuously without requiring external power sources. Here, we extend their theory to include dissipation within the framework of non-Hermitian quantum Hamiltonians. Using Green's function formalism, we…

Quantum Physics · Physics 2024-08-27 Pei-Xin Shen , Zhide Lu , Jose L. Lado , Mircea Trif

We derive a non-Markovian master equation for the evolution of a class of open quantum systems consisting of quadratic fermionic models coupled to wide-band reservoirs. This is done by providing an explicit correspondence between master…

Quantum Physics · Physics 2015-09-09 Pedro Ribeiro , Vitor R. Vieira

We give a conjectural way for computing the $S$-matrix and the correlation functions in quantum field theory beyond perturbation theory. The basic idea seems universal and naively simple: to compute the physical quantities one should…

High Energy Physics - Theory · Physics 2011-06-23 A. V. Stoyanovsky

Explicit solution of a Green function in a non-renormalizable toy model demonstrates that Green functions of the interacting theory fall off much faster than at the tree level at large momenta. This suggests a method of calculations in…

High Energy Physics - Theory · Physics 2007-07-03 H. S. Sharatchandra

A new approach to generalised Casimir type of problems is derived within the context of renormalisable quantum field theory (QFT). We study the simplest case of a massive fluctuating boson field coupled to a time-independent background…

High Energy Physics - Theory · Physics 2007-05-23 Markus Quandt

A quantum transport model incorporating spin scattering processes is presented using the non-equilibrium Green's function (NEGF) formalism within the self-consistent Born approximation. This model offers a unified approach by capturing the…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Ahmet Ali Yanik , Gerhard Klimeck , Supriyo Datta

One of the challenges in diagrammatic simulations of nonequilibrium phenomena in lattice models is the large memory demand for storing momentum-dependent two-time correlation functions. This problem can be overcome with the recently…

Strongly Correlated Electrons · Physics 2025-10-23 Maksymilian Środa , Ken Inayoshi , Hiroshi Shinaoka , Philipp Werner

The theory of real-time quantum many-body dynamics as put forward in Ref. [arXiv:0710.4627] is evaluated in detail. The formulation is based on a generating functional of correlation functions where the Keldysh contour is closed at a given…

Quantum Gases · Physics 2011-02-09 Thomas Gasenzer , Stefan Kessler , Jan M. Pawlowski