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Related papers: Schwinger-Keldysh semionic approach for quantum sp…

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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

We represent the two - dimensional planar classical continuous Heisenberg spin model as a constrained Chern-Simons gauged nonlinear Schr\"odinger system. The hamiltonian structure of the model is studied, allowing the quantization of the…

High Energy Physics - Theory · Physics 2007-05-23 L. Martina , O. K. Pashaev , G. Soliani

We perform a Nf = 2 + 1 lattice QCD simulation to determine the quark spin fractions of hadrons using the Feynman-Hellmann theorem. By introducing an external spin operator to the fermion action, the matrix elements relevant for quark spin…

High Energy Physics - Lattice · Physics 2014-07-30 A. J. Chambers , R. Horsley , Y. Nakamura , H. Perlt , D. Pleiter , P. E. L. Rakow , G. Schierholz , A. Schiller , H. Stüben , R. D. Young , J. M. Zanotti

We investigate the simulation of fermionic systems on a quantum computer. We show in detail how quantum computers avoid the dynamical sign problem present in classical simulations of these systems, therefore reducing a problem believed to…

Condensed Matter · Physics 2009-02-05 G. Ortiz , J. E. Gubernatis , E. Knill , R. Laflamme

This article provides a detailed derivation of the path integral formalism for both boson and fermion quantum open systems using coherent states. The formalism on the imaginary-time axis, Keldysh contour, and Kadanoff contour are given. The…

Quantum Physics · Physics 2025-06-11 Ruofan Chen

Systematic use of the infinite-dimensional spin representation simplifies and rigorizes several questions in Quantum Field Theory. This representation permutes ``Gaussian'' elements in the fermion Fock space, and is necessarily projective:…

High Energy Physics - Theory · Physics 2010-11-01 Jose M. Gracia-Bondia , Joseph C. Varilly

We systematically derive the collision term for the axial kinetic theory, a quantum kinetic theory delineating the coupled dynamics of the vector/axial charges and spin transport carried by the massive spin-1/2 fermions traversing a medium.…

High Energy Physics - Phenomenology · Physics 2020-08-04 Di-Lun Yang , Koichi Hattori , Yoshimasa Hidaka

We introduce the concept of the quark quasifragmentation function (qFF) using an equal-time and spatially boosted form of the Collins-Soper fragmentation function where the out-meson fragment is replaced by the current asymptotic condition.…

High Energy Physics - Phenomenology · Physics 2024-12-30 Sebastian Grieninger , Ismail Zahed

We study quantum spin chains solvable via hidden free fermionic structures. We study the algebras behind such models, establishing connections to the mathematical literature of the so-called ``graph-Clifford'' or ``quasi-Clifford''…

Statistical Mechanics · Physics 2026-02-04 Kohei Fukai , Balázs Pozsgay , István Vona

We derive transport equations for fermions and bosons in spatially or temporally varying backgrounds with special symmetries, by use of the Schwinger-Keldysh formalism. In a noninteracting theory the coherence information is shown to be…

High Energy Physics - Phenomenology · Physics 2014-11-18 Matti Herranen , Kimmo Kainulainen , Pyry M. Rahkila

Two-component spinors are the basic ingredients for describing fermions in quantum field theory in four space-time dimensions. We develop and review the techniques of the two-component spinor formalism and provide a complete set of Feynman…

High Energy Physics - Phenomenology · Physics 2022-05-25 Herbi K. Dreiner , Howard E. Haber , Stephen P. Martin

Non-unitary quantum mechanics has been used in the past to study irreversibility, dissipation and decay in a variety of physical systems. In this letter, we propose a general scheme to deal with systems governed by non-Hermitian…

Mesoscale and Nanoscale Physics · Physics 2011-05-12 Paata Kakashvili , C. J. Bolech

We consider the question of what quantum spin chains naturally encode in their Hilbert space. It turns out that quantum spin chains are rather rich systems, naturally encoding solutions to various problems in combinatorics, group theory,…

Quantum Physics · Physics 2024-07-24 Marcos Crichigno , Anupam Prakash

We present a new supersymmetric approach to the Kondo lattice model in order to describe simultaneously the quasiparticle excitations and the low-energy magnetic fluctuations in heavy-Fermion systems. This approach mixes the fermionic and…

Strongly Correlated Electrons · Physics 2015-06-25 C. Pepin , M. Lavagna

We implement in systems of fermions the formalism of pseudoclassical paths that we recently developed for systems of bosons and show that quantum states of fermionic fields can be described, in the Heisenberg picture, as linear combinations…

High Energy Physics - Theory · Physics 2009-11-10 David H. Oaknin

We examine the quantization of pseudoclassical dynamical systems, models that have classically anticommuting variables, in the Schr\"odinger picture. We quantize these systems, which can be viewed as classical models of particle spin, using…

High Energy Physics - Theory · Physics 2020-02-04 Theodore J. Allen , Donald Spector , Christopher Wilson

We revisit the Jordan-Wigner transformation, showing that --rather than a non-local isomorphism between different fermionic and spin Hamiltonian operators-- it can be viewed in terms of local identities relating different realizations of…

Strongly Correlated Electrons · Physics 2009-11-10 Alberto Anfossi , Arianna Montorsi

We perform the real-time lattice simulation of an open quantum system, which is based on the Schwinger-Keldysh path integral representation of the Lindblad formalism. Although the real-time simulation generally suffers from the sign…

High Energy Physics - Lattice · Physics 2022-07-26 Tomoya Hayata , Yoshimasa Hidaka , Arata Yamamoto

We study the transport properties of generic out-of-equilibrium quantum systems connected to fermionic reservoirs. We develop a new method, based on an expansion of the current in terms of the inverse system size and out of equilibrium…

Statistical Mechanics · Physics 2022-06-28 Tony Jin , João S. Ferreira , Michele Filippone , Thierry Giamarchi

The purpose of this review is to provide a comprehensive pedagogical introduction into Keldysh technique for interacting out-of-equilibrium fermionic and bosonic systems. The emphasis is placed on a functional integral representation of…

Other Condensed Matter · Physics 2015-05-13 Alex Kamenev , Alex Levchenko