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Full-Text Articles in Physics

Stern-Gerlach Dynamics With Quantum Propagators, Bailey C. Hsu, Manuel Berrondo, Jean F. Van Huele Jan 2011

Stern-Gerlach Dynamics With Quantum Propagators, Bailey C. Hsu, Manuel Berrondo, Jean F. Van Huele

Faculty Publications

We study the quantum dynamics of a nonrelativistic neutral particle with spin in inhomogeneous external magnetic fields. We first consider fields with one-dimensional inhomogeneities, both unphysical and physical, and construct the corresponding analytic propagators. We then consider fields with two-dimensional inhomogeneities and develop an appropriate numerical propagation method. We propagate initial states exhibiting different degrees of space localization and various initial spin configurations, including both pure and mixed spin states. We study the evolution of their spin densities and identify characteristic features of spin density dynamics, such as the spatial separation of spin components, and spin localization or accumulation. We …


Spin Dynamics For Wave Packets In Rashba Systems, Bailey C. Hsu, Jean F. Van Huele Jan 2009

Spin Dynamics For Wave Packets In Rashba Systems, Bailey C. Hsu, Jean F. Van Huele

Faculty Publications

We explore spin dynamics for localized wave packets in Rashba systems using spin quantum propagators. We derive exact (one-dimensional) and approximate (two-dimensional) analytic expressions for the propagators and apply them to Gaussian wave packets to obtain localized solutions of systems manifesting Rashba interactions. We observe and describe the evolution of the wave packets. We identify characteristic structures in the wave-packet evolution and look for features with specific spintronics applications such as spin separation and spin accumulation. We discuss the relative importance of those features as a function of the Rashba coupling strength α and the width of the wave packet …


Quantum Electrodynamics Based On Self-Fields, Without Second Quantization: A Nonrelativisitc Calculation Of G – 2, A. O. Barut, Jonathan P. Dowling, Jean F. Van Huele Jan 1988

Quantum Electrodynamics Based On Self-Fields, Without Second Quantization: A Nonrelativisitc Calculation Of G – 2, A. O. Barut, Jonathan P. Dowling, Jean F. Van Huele

Faculty Publications

Using a formulation of quantum electrodynamics that is not second quantized, but rather based on self-fields, we compute the anomalous magnetic moment of the electron to first order in the fine structure constant α. In the nonrelativistic (NR) case and in the dipole approximation, our result is ae≡(g—2)/2=(4Λ/3m)(α/2π), where Λ is a positive photon energy cutoff and m the electron mass. A reasonable choice of cutoff, Λ/m=¾, yields the correct sign and magnitude for g—2 namely, ae=+α/2π. . In our formulation the sign of a3 is correctly positive, …


Quantum Electrodynamics Based On Self-Energy: Lamb Shift And Spontaneous Emission Without Field Quantization, A. O. Barut, Jean F. Van Huele Jan 1985

Quantum Electrodynamics Based On Self-Energy: Lamb Shift And Spontaneous Emission Without Field Quantization, A. O. Barut, Jean F. Van Huele

Faculty Publications

The theory of radiative processes in quantum theory is formulated on the basis of self-energy, in analogy to classical radiation theory, and is explicitly carried out for the calculation of the Lamb shift and spontaneous emission.