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Atomic, Molecular and Optical Physics Commons™
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Articles 1 - 4 of 4
Full-Text Articles in Atomic, Molecular and Optical Physics
Local And Nonlocal Spatial Densities In Quantum Field Theory, R E. Wagner, M R. Ware, E V. Stefanovich, Qichang Su, Rainer Grobe
Local And Nonlocal Spatial Densities In Quantum Field Theory, R E. Wagner, M R. Ware, E V. Stefanovich, Qichang Su, Rainer Grobe
Faculty publications – Physics
We use a one-dimensional model system to compare the predictions of two different yardsticks to compute the position of a particle from its quantum field theoretical state. Based on the first yardstick (defined by the Newton-Wigner position operator), the spatial density can be arbitrarily narrow, and its time evolution is superluminal for short time intervals. Furthermore, two spatially distant particles might be able to interact with each other outside the light cone, which is manifested by an asymmetric spreading of the spatial density. The second yardstick (defined by the quantum field operator) does not permit localized states, and the time …
Time Dilation In Relativistic Two-Particle Interactions, B T. Shields, Rainer Grobe, E V. Stefanovich, M R. Ware, Qichang Su, M C. Morris
Time Dilation In Relativistic Two-Particle Interactions, B T. Shields, Rainer Grobe, E V. Stefanovich, M R. Ware, Qichang Su, M C. Morris
Faculty publications – Physics
We study the orbits of two interacting particles described by a fully relativistic classical mechanical Hamiltonian. We use two sets of initial conditions. In the first set (dynamics 1) the system's center of mass is at rest. In the second set (dynamics 2) the center of mass evolves with velocity V. If dynamics 1 is observed from a reference frame moving with velocity-V, the principle of relativity requires that all observables must be identical to those of dynamics 2 seen from the laboratory frame. Our numerical simulations demonstrate that kinematic Lorentz space-time transformations fail to transform particle observables between the …
Pair Creation Rates For One-Dimensional Fermionic And Bosonic Vacua, T Cheng, M R. Ware, Q Su, Rainer Grobe
Pair Creation Rates For One-Dimensional Fermionic And Bosonic Vacua, T Cheng, M R. Ware, Q Su, Rainer Grobe
Faculty publications – Physics
We compare the creation rates for particle-antiparticle pairs produced by a supercritical force field for fermionic and bosonic model systems. The rates obtained from the Dirac and Klein-Gordon equations can be computed directly from the quantum-mechanical transmission coefficients describing the scattering of an incoming particle with the supercritical potential barrier. We provide a unified framework that shows that the bosonic rates can exceed the fermionic ones, as one could expect from the Pauli-exclusion principle for the fermion system. This imbalance for small but supercritical forces is associated with the occurrence of negative bosonic transmission coefficients of arbitrary size for the …
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 …