Bulletin of the American Physical Society
2018 Annual Meeting of the APS Four Corners Section
Volume 63, Number 16
Friday–Saturday, October 12–13, 2018; University of Utah, Salt Lake City, Utah
Session E05: AMO2: Light-Matter Interactions |
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Chair: Mario Marconi, Colorado State University Room: CSC 208 |
Friday, October 12, 2018 1:30PM - 1:54PM |
E05.00001: Attosecond x-ray science: Probing electron dynamics in molecules and materials Invited Speaker: Arvinder S Sandhu The emergence of attosecond science has enabled the direct measurement and control of dynamics in molecules and materials on the natural timescale of electrons. I will discuss our efforts to expand the scope of attosecond science to explore ‘complex’ processes in molecules and materials, where dynamical complexity stems from various interactions, including the coupling between the electronic and structural degrees of freedom, electronic correlations, external light fields, or a combination thereof. As an example, I will discuss the electronic processes in atoms and molecules, where light fields or nuclear motion induced couplings play an important role. By extending the ultrafast spectroscopy to novel materials, we have also examined electron-phonon interactions and electronic relaxation mechanisms in two-dimensional heterostructures. I will also discuss our efforts to develop light sources that combine the strengths of attosecond spectroscopy and x-ray science, thereby revolutionizing our ability to map and control elementary processes in molecules, interfaces, and quantum materials. |
Friday, October 12, 2018 1:54PM - 2:06PM |
E05.00002: Radiation Scattering from Relativistic Electrons in Intense Laser Light Christoph Schulzke, Justin Peatross Electrons in the focus of a high powered laser undergo relativistic motion. In its average center-of-mass frame, the electron follows a well-known figure-eight trajectory. The resulting radiation pattern of the scattered light is described by a nonlinear equation with an integral solution, as described by Sarachik and Schappert in 1970. They approximated the integral with a series of Bessel functions. We compare the computational requirements of the approximation to performing the integral numerically. We also examine the accuracy and limitations of using a finite number of Bessel functions in the expansion. |
Friday, October 12, 2018 2:06PM - 2:18PM |
E05.00003: Vector Fields in a Focused Laser Beam Brittni Pratt, Justin Bruce Peatross, Michael Ware We use the diffraction formalism developed by V. S. Ignatovsky in 1920 to analyze the vector components of a laser field focused by a parabolic mirror. The Maxwell-respecting fields are expressed in terms of integrals. We compare the results with various closed-form analytic models for the vector fields of a focused Gaussian beam. The relatively simple model developed by Erikson and Singh in 1994 provides best agreement while other models show poor agreement, especially outside of the focal region. The Ignatovsky method assumes the form of the laser beam incident on the mirror, while other approaches assume the form of the beam at the focus. A smooth beam at the mirror, predicts a structured focus, whereas a smooth focus is associated with a structured beam at the mirror, which explains part of the discrepancy between models. |
Friday, October 12, 2018 2:18PM - 2:30PM |
E05.00004: Construction of System to Measure Scattered Harmonics from Electrons in a Laser Focus Daniel Hodge, Michael Ware, Justin Bruce Peatross We are constructing an apparatus to measure the harmonic emission from electrons in a high-intensity laser focus. We use spatial, temporal, and spectral filtering techniques to extract the single-photon-level signal from the much stronger background scattered light. This system is designed to study electron dynamics in a high-intensity focus, and gather information about the detailed vector-field distribution in the laser focus. We present details of the construction of this system and its current status. |
Friday, October 12, 2018 2:30PM - 2:42PM |
E05.00005: Internal Oscillations of a Dark-Bright Soliton in a Harmonic Potential Majed Alotaibi, Lincoln D Carr We investigate the dynamics of a dark-bright soliton in a harmonic potential using a mean-field approach via coupled nonlinear Schr\"odinger equations appropriate to multicomponent Bose-Einstein condensates. We use a modified perturbed dynamical variational Lagrangian approximation, where the perturbation is due to the trap, taken as a Thomas-Fermi profile. The wavefunction ansatz is taken as the correct hyperbolic tangent and secant solutions in the scalar case for the dark and bright components of the soliton, respectively. We also solve the problem numerically with psuedo-spectral Runge-Kutta methods. We find, analytically and numerically, for weak trapping the internal modes are nearly independent of center of mass motion of the dark-bright soliton. In contrast, in tighter traps the internal modes couple strongly to the center of mass motion, showing that for dark-bright solitons in a harmonic potential the center of mass and relative degrees of freedom are not independent. This result is robust against noise in the initial condition and should, therefore, be experimentally observable. |
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