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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 …
Unitary And Nonunitary Approaches In Quantum Field Theory, K D. Lamb, Christopher C. Gerry, Rainer Grobe
Unitary And Nonunitary Approaches In Quantum Field Theory, K D. Lamb, Christopher C. Gerry, Rainer Grobe
Faculty publications – Physics
We use a simplified essential state model to compare two quantum field theoretical approaches to study the creation of electron-positron pairs from the vacuum. In the unitary approach the system is characterized by a state with different numbers of particles that is described by occupation numbers and evolves with conserved norm. The nonunitary approach can predict the evolution of wave functions and density operators with a fixed number of particles but time-dependent norms. As an example to illustrate the differences between both approaches, we examine the degree of entanglement for the Klein paradox, which describes the creation of an electron-positron …
Timing Of Pair Production In Time-Dependent Force Fields, Christopher C. Gerry, Q Su, Rainer Grobe
Timing Of Pair Production In Time-Dependent Force Fields, Christopher C. Gerry, Q Su, Rainer Grobe
Faculty publications – Physics
We examine the creation and annihilation dynamics for electron-positron pairs in a time-dependent but subcritical electric force using a simplified model system. Numerical and semianalytical solutions to computational quantum field theory show that despite the continuity of the quantum field operator in time, the actual number of created particles can change in a discontinuous way if the field changes abruptly. The number of permanently created particles after the pulse, however, increases continuously with the duration of the electric field pulse, suggesting a transition from an exclusive annihilation to a creation regime.
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.