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Starting from the Dirac equation in external electromagnetic and torsion fields we derive a path integral representation for the corresponding propagator. An effective action, which appears in the representation, is interpreted as a…

High Energy Physics - Theory · Physics 2016-12-28 Bodo Geyer , Dmitry Gitman , Ilya Shapiro

We present a theory of magnetotransport through an electronic orbital, where the electron spin interacts with a (sufficiently) large external spin via an exchange interaction. Using a semiclassical approximation, we derive a set of…

Mesoscale and Nanoscale Physics · Physics 2014-10-22 Klemens Mosshammer , Tobias Brandes

We investigate the Dirac equation in the semiclassical limit \hbar --> 0. A semiclassical propagator and a trace formula are derived and are shown to be determined by the classical orbits of a relativistic point particle. In addition, two…

Quantum Physics · Physics 2009-10-31 Jens Bolte , Stefan Keppeler

Radiation reaction is revisited, first in a new classical aproach, where the physical particle 4-momentum is redefined as the energy-momentum flux across the future light cone and is not parallel to the 4-velocity. Then in a semi-classical…

Classical Physics · Physics 2007-05-23 Xavier Artru , Guillaume Bignon , Taoufik Qasmi

We discuss the semiclassical and classical character of the dynamics of a single spin 1/2 coupled to a bath of noninteracting spins 1/2. On the semiclassical level, we extend our previous approach presented in D. Stanek, C. Raas, and G. S.…

Mesoscale and Nanoscale Physics · Physics 2014-08-13 Daniel Stanek , Carsten Raas , Götz S. Uhrig

A perturbation method to analytically describe the dynamics of a classical spinning particle, based on the Mathisson-Papapetrou-Dixon (MPD) equations of motion, is presented. By a power series expansion with respect to the particle's spin…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Dinesh Singh

We derive explicit semiclassical quantisation conditions for the Dirac and Pauli equations. We show that the spin degree of freedom yields a contribution which is of the same order of magnitude as the Maslov correction in…

Quantum Physics · Physics 2009-11-07 Stefan Keppeler

The semiclassical propagation of spin coherent states is considered in complex phase space. For two time-independent systems we find the appropriate classical trajectories and show that their combined contributions are able to describe…

Quantum Physics · Physics 2007-12-04 M. Novaes

Several physical systems can be treated as a scattering process, and, for these processes, a natural observed quantity arises: the ratio between the reflected and incident intensities, known as the reflection coefficient. This dissertation…

General Relativity and Quantum Cosmology · Physics 2014-07-15 Bruno Arderucio

We numerically study the dynamics and stationary states of a spin ensemble strongly coupled to a single-mode resonator subjected to loss and external driving. Employing a generalized cumulant expansion approach we analyze finite-size…

Quantum Physics · Physics 2019-08-06 Matthias Zens , Dmitry O. Krimer , Stefan Rotter

Using classical description of spin degrees of freedom, we extend recent formulation of the perfect-fluid hydrodynamics for spin-polarized fluids to the case including dissipation. Our work is based on the analysis of classical kinetic…

Superradiance and subradiance are collective effects that emerge from coherent interactions between quantum emitters. Due to their many-body nature, theoretical studies of extended samples with length larger than the atomic transition…

Quantum Physics · Physics 2022-12-02 Oriol Rubies-Bigorda , Susanne F. Yelin

We point out that a certain kind of combined classical translational and spin dynamics -- claimed in [M. Pletyukhov, et al. Phys. Rev. Lett. 89 (2002) 116601] to arise from the Pauli equation in the semiclassical limit $\hbar\to0$ for fixed…

Chaotic Dynamics · Physics 2007-05-23 Jens Bolte , Rainer Glaser , Stefan Keppeler

We present an analytical approach for the study of driven Dicke superradiance based on a Heisenberg-Langevin formulation. We calculate the steady-state fluctuations of both the atomic-spin and the light-field operators. While the atoms…

Quantum Physics · Physics 2023-04-17 Ori Somech , Yoav Shimshi , Ephraim Shahmoon

Quantum spin-flip transitions are of great importance in the synchrotron radiation theory. For better understanding of the nature of this phenomenon, it is necessary to except the effects connected with the electric charge radiation from…

Quantum Physics · Physics 2009-11-07 V. A. Bordovitsyn , V. S. Gushchina , A. N. Myagkii

The theoretical foundations of the phenomenon known as super-radiance still continues to attract considerable attention. Despite many valiant attempts at pedagogically clear presentations, the effect nevertheless still continues to generate…

General Relativity and Quantum Cosmology · Physics 2014-09-17 Petarpa Boonserm , Tritos Ngampitipan , Matt Visser

Bifurcations of classical orbits introduce divergences into semiclassical spectra which have to be smoothed with the help of uniform approximations. We develop a technique to extract individual energy levels from semiclassical spectra…

Chaotic Dynamics · Physics 2009-11-07 T. Bartsch , J. Main , G. Wunner

It is shown how initial conditions can be appropriately defined for the integration of Lorentz-Dirac equations of motion. The integration is performed \QTR{it}{forward} in time. The theory is applied to the case of the motion of an electron…

General Physics · Physics 2009-11-07 M. S. Hussein , M. P. Pato , J. C. Wells

The relativistic semiclassical evolution of the position of an electron in the presence of an external electromagnetic field is studied in terms of a Newton equation that incorporates spin effects directly. This equation emerges from the…

Quantum Physics · Physics 2017-11-13 R. Gutierrez-Jauregui , R. Perez-Pascual , R. Jauregui

We derive semiclassical quantization conditions for systems with spin. To this end one has to define the notion of integrability for the corresponding classical system which is given by a combination of the translational motion and…

Quantum Physics · Physics 2009-11-07 Stefan Keppeler