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Full-Text Articles in Physics
Transitions Into The Negative-Energy Dirac Continuum, P Krekora, Q Su, Rainer Grobe
Transitions Into The Negative-Energy Dirac Continuum, P Krekora, Q Su, Rainer Grobe
Faculty publications – Physics
We compare the predictions of the single-particle Dirac equation with quantum field theory for an electron subjected to a space and time dependent field. We demonstrate analytically and numerically that a transition into the negative-energy subspace predicted by the single-particle Dirac equation is directly associated with the degree of suppression of pair-production as described by quantum field theory. We show that the portion of the mathematical wave function that populates the negative-energy states corresponds to the difference between the positron spatial density for systems with and without an electron initially present.
Effects Of Relativity On The Time-Resolved Tunneling Of Electron Wave Packets, P Krekora, Q Su, Rainer Grobe
Effects Of Relativity On The Time-Resolved Tunneling Of Electron Wave Packets, P Krekora, Q Su, Rainer Grobe
Faculty publications – Physics
We solve numerically the time-dependent Dirac equation for a quantum wave packet tunneling through a potential barrier. We analyze the spatial probability distribution of the transmitted wave packet in the context of the possibility of effectively superluminal peak and front velocities of the electron during tunneling. Both the Dirac and Schrodinger theories predict superluminal tunneling speeds. However, in contrast to the Dirac theory the Schrodinger equation allows a possible violation of causality. Based on an analysis of the tunneling process in full temporal and spatial resolution, we introduce an instantaneous tunneling speed that can be computed inside the potential barrier.
Dirac Theory Of Ring-Shaped Electron Distributions In Atoms, P Krekora, R E. Wagner, Q Su, Rainer Grobe
Dirac Theory Of Ring-Shaped Electron Distributions In Atoms, P Krekora, R E. Wagner, Q Su, Rainer Grobe
Faculty publications – Physics
The time-dependent Dirac equation is solved numerically on a space-time grid for an atom in a strong static magnetic field and a laser field. The resonantly induced relativistic motion of the atomic electron leads to a ringlike spatial probability density similar to the features that have been recently predicted [Wagner, Su, and Grobe, Phys. Rev. Lett. 84, 3282 (2000)] based on a phase-space method. We further demonstrate that spin-orbit coupling for a fast-moving electron in such an atom becomes significant and the time dependence of the spin can dephase even if initially aligned parallel to the direction of the static …