Open Access. Powered by Scholars. Published by Universities.®
Atomic, Molecular and Optical Physics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 3 of 3
Full-Text Articles in Atomic, Molecular and Optical Physics
Locality In The Creation Of Electron-Positron Pairs, T Cheng, S P. Bowen, C C. Gerry, Rainer Grobe
Locality In The Creation Of Electron-Positron Pairs, T Cheng, S P. Bowen, C C. Gerry, Rainer Grobe
Faculty publications – Physics
We examine the mathematical solutions of the Dirac equation to predict the spontaneous electron-positron pair creation from the vacuum. The Dirac equation contains a position and time-dependent scalar potential to approximate the effect of an external force on the vacuum. We focus on forces that are localized in space as well as in time and find that the resulting creation process is also localized in time but delocalized in space. This illustrates that the Dirac equation can show nonlocal behavior as it predicts that particles can be created even in spatial regions where the force is zero. We also examine …
Interpretational Difficulties In Quantum Field Theory, P Krekora, Q Su, Rainer Grobe
Interpretational Difficulties In Quantum Field Theory, P Krekora, Q Su, Rainer Grobe
Faculty publications – Physics
Based on space-time-resolved solutions to relativistic quantum field theory we illustrate interpretational difficulties in associating field-theoretical quantities with properties of particles. These difficulties are related to the fact that the definition of the spatial probability density of particles depends on the choice of the Hilbert subspace on which the field operator is projected. We illustrate these problems by analyzing pair-production probabilities and spatial densities for the electron-positron dynamics associated with a spatially localized subcritical potential that is turned on and off in time.
Critique Of The Wigner Tunneling Speed And A Proposed Alternative, P Krekora, Q Su, Rainer Grobe
Critique Of The Wigner Tunneling Speed And A Proposed Alternative, P Krekora, Q Su, Rainer Grobe
Faculty publications – Physics
In the context of superluminal propagation of wave packets through potential barriers, the tunneling speed is usually characterized by the Wigner velocity. We propose an alternative speed that takes into account the interference between the incoming and the reflected waves and leads to a better estimation of arrival time for a wave packet entering the tunneling region. This arrival time is derived by an extrapolation from inside the barrier. The analytical theory is based on the stationary phase approximation whose validity is justified by a comparison with the numerical solution of the time-dependent Dirac equation.