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We study a two-electron quantum dot molecule in a magnetic field by the direct diagonalization of the Hamiltonian matrix. The ground states of the molecule with the total spin S=0 and S=1 provide a possible realization for a qubit of a…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 A. Harju , S. Siljamäki , R. M. Nieminen

In this work the worldline quantum field theory (WQFT) approach to computing observables of the classical general relativistic two-body system is presented. Compact bodies such as black holes or neutron stars are described in an effective…

High Energy Physics - Theory · Physics 2023-08-09 Gustav Uhre Jakobsen

Interacting spins in quantum magnet can cooperate and exhibit exotic states like the quantum spin liquid. To explore the materialization of such intriguing states, the determination of effective spin Hamiltonian of the quantum magnet is…

Strongly Correlated Electrons · Physics 2021-09-01 Sizhuo Yu , Yuan Gao , Bin-Bin Chen , Wei Li

We revisit the Schrieffer-Wolff transformation and present a path integral version of this important canonical transformation. The equivalence between the low-energy sector of the Anderson model in the so-called local moment regime and the…

Strongly Correlated Electrons · Physics 2016-07-08 Farzaneh Zamani , Pedro Ribeiro , Stefan Kirchner

Here I present a new discrete model of quantum mechanics for relativistic 1-electron systems, in which particle movement is described by a directed space-time graph with attached 4-spinors, but without any continuous wave functions. These…

Quantum Physics · Physics 2007-05-23 Wolfgang Koehler

The motion of a particle with a spin in spherical harmonic oscillator potential with spin-orbit interaction is studied. We have focus our attention on spatial motion of wave packets, giving a description complementary to motion of spin…

Quantum Physics · Physics 2009-10-28 P. Rozmej , R. Arvieu

An introduction to spin techniques in particle physics is given. Among the topics covered are: helicity formalism and its applications to the decay and scattering of spin-1/2 and spin-1 particles, techniques for evaluating helicity…

High Energy Physics - Phenomenology · Physics 2009-09-25 Howard E. Haber

Spin wave theory is a key ingredient in our comprehension of quantum spin systems, and is used successfully for understanding a wide range of magnetic phenomena, including magnon condensation and stability of patterns in dipolar systems.…

Statistical Mechanics · Physics 2015-06-19 Michele Correggi , Alessandro Giuliani , Robert Seiringer

We consider singular self-adjoint extensions for one-dimensional Schr\"{o}dinger operator for two-component wave function within the framework of the distribution theory for discontinuous test functions…

Mathematical Physics · Physics 2019-08-07 Vladimir Kulinskii , Dmitry Panchenko

A description of non-collinear magnetism in the framework of spin-density functional theory is presented for the exact exchange energy functional which depends explicitly on two-component spinor orbitals. The equations for the effective…

We address the problem of obtaining the exact reduced dynamics of the spin-half (qubit) immersed within the bosonic bath (enviroment). An exact solution of the Schrodinger equation with the paradigmatic spin-boson Hamiltonian is obtained.…

Quantum Physics · Physics 2011-04-14 Bartlomiej Gardas

We summarize the recent theoretical and numerical works on spin turbulence (ST) in spin-1 spinor Bose-Einstein condensates. When the system is excited from the ground state, it goes through hy- drodynamic instability to ST in which the spin…

Quantum Gases · Physics 2015-06-18 Makoto Tsubota , Kazuya Fujimoto

Spin precession in magnetic materials is commonly modelled with the classical phenomenological Landau-Lifshitz-Gilbert (LLG) equation. Based on a quantized spin+environment Hamiltonian, we here derive a general spin operator equation of…

Quantum Physics · Physics 2022-11-02 J. Anders , C. R. J. Sait , S. A. R. Horsley

We extend the Shirafuji model for massless particles with primary spacetime coordinates and composite four-momenta to a model for massive particles with spin and electric charge. The primary variables in the model are the spacetime…

High Energy Physics - Theory · Physics 2007-05-23 Sergey Fedoruk , Andrzej Frydryszak , Jerzy Lukierski , Cèsar Miquel-Espanya

Central spin models, where a single spinful particle interacts with a spin environment, find wide application in quantum information technology and can be used to describe, e.g., the decoherence of a qubit over time. We propose a method of…

Quantum Physics · Physics 2023-11-30 Jacek Dobrzyniecki , Michał Tomza

We describe an efficient numerical method for simulating the dynamics and steady states of collective spin systems in the presence of dephasing and decay. The method is based on the Schwinger boson representation of spin operators and uses…

Quantum Physics · Physics 2021-05-18 Julian Huber , Peter Kirton , Peter Rabl

We analyze the spin-orbit terms in multi-subband quasi-two-dimensional electron systems, and how they descend from the bulk Hamiltonian of the conduction band. Measurements of spin-orbit terms in one subband alone are shown to give…

Mesoscale and Nanoscale Physics · Physics 2008-11-03 K. V. Kavokin , M. E. Portnoi

An accurate description of the two-electron density, crucial for magnetic coupling in spin systems, provides in general a major challenge for density functional theory calculations. It affects, e.g., the calculated zero-field splitting…

Quantum Physics · Physics 2020-05-06 Timur Biktagirov , Wolf Gero Schmidt , Uwe Gerstmann

Molecular nanomagnets show clear signatures of coherent behavior and have a wide variety of effective low-energy spin Hamiltonians suitable for encoding qubits and implementing spin-based quantum information processing. At the nanoscale,…

Mesoscale and Nanoscale Physics · Physics 2013-05-29 Mircea Trif , Filippo Troiani , Dimitrije Stepanenko , Daniel Loss

We give an example of topological theory whose Hilbert space contains physical objects: the N=2 supersymmetric Lagrangian of spin-one particles moving in D-dimensional space-time equals the Lagrangian of a topological sigma model in a…

High Energy Physics - Theory · Physics 2007-05-23 Romain Attal , Laurent Baulieu