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Articles 31 - 60 of 68
Full-Text Articles in Physics
Computational Study Of The Near Field Spontaneous Creation Of Photonic States Coupled To Few Level Systems, Sergio Tafur
Computational Study Of The Near Field Spontaneous Creation Of Photonic States Coupled To Few Level Systems, Sergio Tafur
Electronic Theses and Dissertations
Models of the spontaneous emission and absorption of photons coupled to the electronic states of quantum dots, molecules, N-V (single nitrogen vacancy) centers in diamond, that can be modeled as artificial few level atoms, are important to the development of quantum computers and quantum networks. A quantum source modeled after an effective few level system is strongly dependent on the type and coupling strength the allowed transitions. These selection rules are subject to the Wigner-Eckert theorem which specifies the possible transitions during the spontaneous creation of a photonic state and its subsequent emission. The model presented in this dissertation describes …
Self-Imaging Of Molecules From Diffraction Spectra By Laser-Induced Rescattering Electrons, Junliang Xu, Zhangjin Chen, Anh-Thu Le, C. D. Lin
Self-Imaging Of Molecules From Diffraction Spectra By Laser-Induced Rescattering Electrons, Junliang Xu, Zhangjin Chen, Anh-Thu Le, C. D. Lin
Physics Faculty Research & Creative Works
We study high-energy angle-resolved photoelectron spectra of molecules in strong fields. In an oscillating laser electric field, electrons released earlier in the pulse may return to recollide with the target ion, in a process similar to scattering by laboratory prepared electrons. If midinfrared lasers are used, we show that the images generated by the returning electrons are similar to images observed in typical gas-phase electron diffraction (GED). These spectra can be used to retrieve the positions of atoms in a molecule as in GED. Since infrared laser pulses of durations of a few femtoseconds are already available today, the study …
Frequency Dependence In The Initiation Of Laser-Induced Damage, Jeremy Gulley
Frequency Dependence In The Initiation Of Laser-Induced Damage, Jeremy Gulley
Jeremy R. Gulley
Numerous studies have investigated the role of photoionization in ultrafast laser-induced damage of bulk dielectrics. This study examines the role of spectral width and instantaneous laser frequency in laser-induced damage using a frequency dependent multiphoton ionization model and numerical simulation of an 800 nm laser pulse propagating through fused silica. When the individual photon wavelengths are greater than 827 nm, an additional photon is required for photoionization, reducing the probability of the event by many orders of magnitude. Simulation results suggest that this frequency dependence may significantly affect the processes of laser-induced damage and filamentation.
Investigating Two-Photon Double Ionization Of D₂ By Xuv-Pump-Xuv-Probe Experiments, Yuhai Jiang, Artem Rudenko, Jhon Fredy Perez-Torres, Oliver Herrwerth, Lutz M. Foucar, Moritz Kurka, Kai Uwe Kuhnel, M. Toppin, Etienne Plesiat, Felipe Morales, Fernando Javier Martin, Matthias Lezius, Matthias F. Kling, Till Jahnke, Reinhard Dorner, Jose Luis Sanz-Vicario, Jeroen Van Tilborg, Ali Belkacem, Michael Schulz, Kiyoshi Ueda, Stefan Dusterer, Rolf Treusch, Claus Dieter Schroter, Robert Moshammer, Joachim Hermann Ullrich
Investigating Two-Photon Double Ionization Of D₂ By Xuv-Pump-Xuv-Probe Experiments, Yuhai Jiang, Artem Rudenko, Jhon Fredy Perez-Torres, Oliver Herrwerth, Lutz M. Foucar, Moritz Kurka, Kai Uwe Kuhnel, M. Toppin, Etienne Plesiat, Felipe Morales, Fernando Javier Martin, Matthias Lezius, Matthias F. Kling, Till Jahnke, Reinhard Dorner, Jose Luis Sanz-Vicario, Jeroen Van Tilborg, Ali Belkacem, Michael Schulz, Kiyoshi Ueda, Stefan Dusterer, Rolf Treusch, Claus Dieter Schroter, Robert Moshammer, Joachim Hermann Ullrich
Physics Faculty Research & Creative Works
We used a split-mirror setup attached to a reaction microscope at the free-electron laser in Hamburg (FLASH) to perform an XUV-pump-XUV-probe experiment by tracing the ultrafast nuclear wave-packet motion in the D2 +(1sσg) with <10 fs time resolution. Comparison with time-dependent calculations shows excellent agreement with the measured vibrational period of 22±4 fs in D2+, points to the importance of accurately knowing the internuclear distance-dependent ionization probability, and paves the way to control sequential and nonsequential two-photon double-ionization contributions.
Theoretical Study Of Photoelectron Angular Distributions In Single-Photon Ionization Of Aligned N₂ And Co₂, Cheng Jin, Anh-Thu Le, Song-Feng Zhao, R. R. Lucchese, C. D. Lin
Theoretical Study Of Photoelectron Angular Distributions In Single-Photon Ionization Of Aligned N₂ And Co₂, Cheng Jin, Anh-Thu Le, Song-Feng Zhao, R. R. Lucchese, C. D. Lin
Physics Faculty Research & Creative Works
We calculate photoelectron angular distributions (PADs) resulting from single-photon (43 eV) ionization of molecules that have been transiently aligned with a short laser pulse. The total ionization cross sections of N₂ and CO₂ vs the time delay between the aligning laser pulse and the soft x-ray photon are calculated and compared to experimental results reported by I. Thomann et al. [J. Phys. Chem. A 112, 9382 (2008)]. We present the PADs from these aligned molecules in the laboratory frame which can be compared directly with future experiments from aligned N₂ and CO₂. The alignment dependence of single-photon ionization, multiphoton ionization, …
Modeling And Design Of A Photonic Crystal Chip Hosting A Quantum Network Made Of Single Spins In Quantum Dots That Interact Via Single Photons, Hubert P. Seigneur
Modeling And Design Of A Photonic Crystal Chip Hosting A Quantum Network Made Of Single Spins In Quantum Dots That Interact Via Single Photons, Hubert P. Seigneur
Electronic Theses and Dissertations
In this dissertation, the prospect of a quantum technology based on a photonic crystal chip hosting a quantum network made of quantum dot spins interacting via single photons is investigated. The mathematical procedure to deal with the Liouville-Von Neumann equation, which describes the time-evolution of the density matrix, was derived for an arbitrary system, giving general equations. Using this theoretical groundwork, a numerical model was then developed to study the spatiotemporal dynamics of entanglement between various qubits produced in a controlled way over the entire quantum network. As a result, an efficient quantum interface was engineered allowing for storage qubits …
Correlated Two-Photon Emission By Transitions Of Dirac-Volkov States In Intense Laser Fields: Qed Predictions, Erik Lotstedt, Ulrich D. Jentschura
Correlated Two-Photon Emission By Transitions Of Dirac-Volkov States In Intense Laser Fields: Qed Predictions, Erik Lotstedt, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
In an intense laser field, an electron may decay by emitting a pair of photons. The two photons emitted during the process, which can be interpreted as a laser-dressed double Compton scattering, remain entangled in a quantifiable way: namely, the so-called concurrence of the photon polarizations gives a gauge-invariant measure of the correlation of the hard gamma rays. We calculate the differential rate and concurrence for a backscattering setup of the electron and photon beam, employing Volkov states and propagators for the electron lines, thus accounting nonperturbatively for the electron-laser interaction. The nonperturbative results are shown to differ significantly compared …
Relativistic (Zα)2 Corrections And Leading Quantum Electrodynamic Corrections To The Two-Photon Decay Rate Of Ionic States, Benedikt J. Wundt, Ulrich D. Jentschura
Relativistic (Zα)2 Corrections And Leading Quantum Electrodynamic Corrections To The Two-Photon Decay Rate Of Ionic States, Benedikt J. Wundt, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
We calculate the relativistic corrections of relative order (Zα) 2 to the two-photon decay rate of higher excited S and D states in ionic atomic systems, and we also evaluate the leading radiative corrections of relative order α (Zα) 2 ln [(Zα) -2]. We thus complete the theory of the two-photon decay rates up to relative order α3 ln (α). An approach inspired by nonrelativistic quantum electrodynamics is used. We find that the corrections of relative order (Zα) 2 to the two-photon decay are given by the Zitterbewegung, by the spin-orbit coupling and by relativistic corrections to the electron mass, …
Quantitative Rescattering Theory For Laser-Induced High-Energy Plateau Photoelectron Spectra, Zhangjin Chen, Anh-Thu Le, Toru Morishita, C. D. Lin
Quantitative Rescattering Theory For Laser-Induced High-Energy Plateau Photoelectron Spectra, Zhangjin Chen, Anh-Thu Le, Toru Morishita, C. D. Lin
Physics Faculty Research & Creative Works
A comprehensive quantitative rescattering (QRS) theory for describing the production of high-energy photoelectrons generated by intense laser pulses is presented. According to the QRS, the momentum distributions of these electrons can be expressed as the product of a returning electron wave packet with the elastic differential cross sections (DCS) between free electrons with the target ion. We show that the returning electron wave packets are determined mostly by the lasers only and can be obtained from the strong field approximation. The validity of the QRS model is carefully examined by checking against accurate results from the solution of the time-dependent …
Accurate Retrieval Of Target Structures And Laser Parameters Of Few-Cycle Pulses From Photoelectron Momentum Spectra, Samuel Micheau, Zhangjin Chen, Anh-Thu Le, J. Rauschenberger, M. F. Kling, C. D. Lin
Accurate Retrieval Of Target Structures And Laser Parameters Of Few-Cycle Pulses From Photoelectron Momentum Spectra, Samuel Micheau, Zhangjin Chen, Anh-Thu Le, J. Rauschenberger, M. F. Kling, C. D. Lin
Physics Faculty Research & Creative Works
We illustrate a new method of analyzing three-dimensional momentum images of high-energy photoelectrons generated by intense phase-stabilized few-cycle laser pulses. Using photoelectron momentum spectra that were obtained by velocity-map imaging of above-threshold ionization of xenon and argon targets, we show that the absolute carrier-envelope phase, the laser peak intensity, and pulse duration can be accurately determined simultaneously (with an error of a few percent). We also show that the target structure, in the form of electron-target ion elastic differential cross sections, can be retrieved over a range of energies. The latter offers the promise of using laser-generated electron spectra for …
Coulomb-Field-Induced Conversion Of A High-Energy Photon Into A Pair Assisted By A Counterpropagating Laser Beam, Erik Lotstedt, Ulrich D. Jentschura, Christoph H. Keitel
Coulomb-Field-Induced Conversion Of A High-Energy Photon Into A Pair Assisted By A Counterpropagating Laser Beam, Erik Lotstedt, Ulrich D. Jentschura, Christoph H. Keitel
Physics Faculty Research & Creative Works
The laser-induced modification of a fundamental process of quantum electrodynamics, the conversion of a high-energy gamma photon in the Coulomb field of a nucleus into an electron-positron pair, is studied theoretically. Although the employed formalism allows for the general case where the gamma photon and laser photons cross at an arbitrary angle, we here focus on a theoretically interesting and numerically challenging setup, where the laser beam and gamma photon counterpropagate and impinge on a nucleus at rest. For a peak laser field smaller than the critical Schwinger field and gamma photon energy larger than the field-free threshold, the total …
Laser Channeling Of Bethe-Heitler Pairs, Erik Lotstedt, Ulrich D. Jentschura, Christoph H. Keitel
Laser Channeling Of Bethe-Heitler Pairs, Erik Lotstedt, Ulrich D. Jentschura, Christoph H. Keitel
Physics Faculty Research & Creative Works
Electron-positron pair creation is analyzed for an arrangement involving three external fields: a high-frequency gamma photon, the Coulomb field of a nucleus, and a strong laser wave. The frequency of the incoming gamma photon is assumed to be larger than the threshold for pair production in the absence of a laser, and the peak electric field of the laser is assumed to be much weaker than Schwinger's critical field. The total number of pairs produced is found to be essentially unchanged by the laser field, while the differential cross section is drastically modified. We show that the laser can channel …
Potential For Ultrafast Dynamic Chemical Imaging With Few-Cycle Infrared Lasers, Toru Morishita, Anh-Thu Le, Zhangjin Chen, C. D. Lin
Potential For Ultrafast Dynamic Chemical Imaging With Few-Cycle Infrared Lasers, Toru Morishita, Anh-Thu Le, Zhangjin Chen, C. D. Lin
Physics Faculty Research & Creative Works
We studied the photoelectron spectra generated by an intense few cycle infrared laser pulse. By focusing on the angular distributions of the back rescattered high energy photoelectrons, we show that accurate differential elastic scattering cross-sections of the target ion by free electrons can be extracted. Since the incident direction and the energy of the free electrons can be easily changed by manipulating the laser's polarization, intensity and wavelength, these extracted elastic scattering cross-sections, in combination with more advanced inversion algorithms, may be used to reconstruct the effective single-scattering potential of the molecule, thus opening up the possibility of using few-cycle …
Quantum Dot Resonant Tunneling Diode For Telecommunication Wavelength Single Photon Detection, H. W. Li, B. E. Kardynał, P. See, A. J. Shields, P. Simmonds, H. E. Beere, D. A. Ritchie
Quantum Dot Resonant Tunneling Diode For Telecommunication Wavelength Single Photon Detection, H. W. Li, B. E. Kardynał, P. See, A. J. Shields, P. Simmonds, H. E. Beere, D. A. Ritchie
Paul J. Simmonds
The authors present a quantum dot (QD) based single photon detector operating at a fiber optic telecommunication wavelength. The detector is based on an AlAs/In0.53Ga0.47As/AlAs double-barrier resonant tunneling diode containing a layer of self-assembled InAs QDs grown on an InP substrate. The device shows an internal efficiency of about 6.3% with a dark count rate of 1.58 × 10−6 ns−1 for 1310 nm photons.
Bremsstrahlung In Α Decay Reexamined, H. Boie, Heiko Scheit, Ulrich D. Jentschura, F. Kock, M. Lauer, A. I. Milstein, Ivan S. Terekhov, Dirk Schwalm
Bremsstrahlung In Α Decay Reexamined, H. Boie, Heiko Scheit, Ulrich D. Jentschura, F. Kock, M. Lauer, A. I. Milstein, Ivan S. Terekhov, Dirk Schwalm
Physics Faculty Research & Creative Works
A high-statistics measurement of bremsstrahlung emitted in the α decay of 210Po has been performed, which allows us to follow the photon spectra up to energies of ~500keV. The measured differential emission probability is in good agreement with our theoretical results obtained within the quasiclassical approximation as well as with the exact quantum mechanical calculation. It is shown that, due to the small effective electric dipole charge of the radiating system, a significant interference between the electric dipole and quadrupole contributions occurs, which is altering substantially the angular correlation between the α particle and the emitted photon.
Photon Angular Distribution And Nuclear-State Alignment In Nuclear Excitation By Electron Capture, Adriana Palffy, Zoltan Harman, Andrey S. Surzhykov, Ulrich D. Jentschura
Photon Angular Distribution And Nuclear-State Alignment In Nuclear Excitation By Electron Capture, Adriana Palffy, Zoltan Harman, Andrey S. Surzhykov, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
The alignment of nuclear states resonantly formed in nuclear excitation by electron capture (NEEC) is studied by means of a density matrix technique. The vibrational excitations of the nucleus are described by a collective model and the electrons are treated in a relativistic framework. Formulas for the angular distribution of photons emitted in the nuclear relaxation are derived. We present numerical results for alignment parameters and photon angular distributions for a number of heavy elements in the case of E2 nuclear transitions. Our results are intended to help future experimental attempts to discern NEEC from radiative recombination, which is the …
Analysis Of Two-Dimensional Photoelectron Momentum Spectra And The Effect Of The Long-Range Coulomb Potential In Single Ionization Of Atoms By Intense Lasers, Zhangjin Chen, Toru Morishita, Anh-Thu Le, M. Wickenhauser, X. M. Tong, C. D. Lin
Analysis Of Two-Dimensional Photoelectron Momentum Spectra And The Effect Of The Long-Range Coulomb Potential In Single Ionization Of Atoms By Intense Lasers, Zhangjin Chen, Toru Morishita, Anh-Thu Le, M. Wickenhauser, X. M. Tong, C. D. Lin
Physics Faculty Research & Creative Works
Two-dimensional (2D) electron momentum distributions and energy spectra for multiphoton ionization of atoms by intense laser pulses, calculated by solving the time-dependent Schrödinger equation (TDSE) for different wavelengths and intensities, are compared to those predicted by the strong-field approximation (SFA). It is shown that the momentum spectra at low energies between the TDSE and SFA are quite different and the differences arise largely from the absence of a long-range Coulomb interaction in the SFA. We further found that the low-energy 2D momentum spectra from the TDSE exhibit ubiquitous fanlike features where the number of stripes is due to a single …
Detectability Of Dissipative Motion In Quantum Vacuum Via Superradiance, Woo-Joong Kim, James Hayden Brownell, Roberto Onofrio
Detectability Of Dissipative Motion In Quantum Vacuum Via Superradiance, Woo-Joong Kim, James Hayden Brownell, Roberto Onofrio
Dartmouth Scholarship
We propose an experiment for generating and detecting vacuum-induced dissipative motion. A high frequency mechanical resonator driven in resonance is expected to dissipate mechanical energy in quantum vacuum via photon emission. The photons are stored in a high quality electromagnetic cavity and detected through their interaction with ultracold alkali-metal atoms prepared in an inverted population of hyperfine states. Superradiant amplification of the generated photons results in a detectable radio- frequency signal temporally distinguishable from the expected background.
Two-Photon Excitation Dynamics In Bound Two-Body Coulomb Systems Including Ac Stark Shift And Ionization, Martin K. Haas, Ulrich D. Jentschura, Christoph H. Keitel, Nikolai N. Kolachevsky, Maximilian Herrmann, Peter Fendel, Marc P. Fischer, Th H. Udem, Ronald Holzwarth, Theodor Wolfgang Hansch, Marlan O. Scully, Girish S. Agarwal
Two-Photon Excitation Dynamics In Bound Two-Body Coulomb Systems Including Ac Stark Shift And Ionization, Martin K. Haas, Ulrich D. Jentschura, Christoph H. Keitel, Nikolai N. Kolachevsky, Maximilian Herrmann, Peter Fendel, Marc P. Fischer, Th H. Udem, Ronald Holzwarth, Theodor Wolfgang Hansch, Marlan O. Scully, Girish S. Agarwal
Physics Faculty Research & Creative Works
One of the dominant systematic effects that shift resonance lines in high-precision measurements of two-photon transitions is the dynamic (ac) Stark shift. For suitable laser frequencies, the ac Stark shift acquires an imaginary part which corresponds to the rate of resonant one-photon ionization of electrons into a continuum state. At the current level of spectroscopic accuracy, the underlying time-dependent quantum dynamics governing the atomic two-photon excitation process must be well understood, and related considerations are the subject of the present paper. In order to illustrate the basic mechanisms in the transient regime, we investigate an analytically solvable model scenario for …
Characteristics Of Two-Dimensional Triangular And Three-Dimensional Face-Centered-Cubic Photonic Crystals, Jeffery D. Clark
Characteristics Of Two-Dimensional Triangular And Three-Dimensional Face-Centered-Cubic Photonic Crystals, Jeffery D. Clark
Theses and Dissertations
The fabrication of photonic crystals (PhC) with photonic band gaps (PBG) in the visible range is a difficult task due to the small structural feature sizes of the PhC. The particular type of PhC examined is a two-dimensional (2-D) triangular structure with a PBG designed for visible wavelengths with applications in visible integrated photonic systems. This work examines the processes involved and viability of fabricating 2-D triangular PhC's by a variety of techniques: focused ion beam, electron lithography and holographic photo-polymerization/lithography. The design of the PhC was based on a program created to display gap maps for triangular structures. The …
Photoionization Broadening Of The 1s-2s Transition In A Beam Of Atomic Hydrogen, Nikolai N. Kolachevsky, Martin K. Haas, Ulrich D. Jentschura, Maximilian Herrmann, Peter Fendel, Marc P. Fischer, Ronald Holzwarth, Th H. Udem, Christoph H. Keitel, Theodor Wolfgang Hansch
Photoionization Broadening Of The 1s-2s Transition In A Beam Of Atomic Hydrogen, Nikolai N. Kolachevsky, Martin K. Haas, Ulrich D. Jentschura, Maximilian Herrmann, Peter Fendel, Marc P. Fischer, Ronald Holzwarth, Th H. Udem, Christoph H. Keitel, Theodor Wolfgang Hansch
Physics Faculty Research & Creative Works
We consider the excitation dynamics of the two-photon 1S - 2S transition in a beam of atomic hydrogen by 243 nm laser radiation. Specifically, we study the impact of ionization damping on the transition line shape, caused by the possibility of ionization of the 2S level by the same laser field. Using a Monte Carlo simulation, we calculate the line shape of the 1S - 2S transition for the experimental geometry used in the two latest absolute frequency measurements [M. Niering, Phys. Rev. Lett. 84, 5496 (2000) and M. Fischer, Phys. Rev. Lett. 92, 230802 (2004)]. The calculated line shift …
Self-Energy Values For P States In Hydrogen And Low-Z Hydrogenlike Ions, Ulrich D. Jentschura, Peter J. Mohr
Self-Energy Values For P States In Hydrogen And Low-Z Hydrogenlike Ions, Ulrich D. Jentschura, Peter J. Mohr
Physics Faculty Research & Creative Works
We describe a nonperturbative (in Z α ) numerical evaluation of the one-photon electron self-energy for 3P1/2 , 3P3/2 , 4P1/2, and 4P3/2 states in hydrogenlike atomic systems with charge numbers Z = 1 to 5. The numerical results are found to be in agreement with known terms in the expansion of the self-energy in powers of Z α and lead to improved theoretical predictions for the self-energy shift of these states.
Optimization Of Ultraviolet Emission And Chemical Species Generation From A Pulsed Dielectric Barrier Discharge At Atmospheric Pressure, Xinpei Lu, Mounir Laroussi
Optimization Of Ultraviolet Emission And Chemical Species Generation From A Pulsed Dielectric Barrier Discharge At Atmospheric Pressure, Xinpei Lu, Mounir Laroussi
Electrical & Computer Engineering Faculty Publications
One of the attractive features of nonthermal atmospheric pressure plasmas is the ability to achieve enhanced gas phase chemistry without the need for elevated gas temperatures. This attractive characteristic recently led to their extensive use in applications that require low temperatures, such as material processing and biomedical applications. The agents responsible for the efficient plasma reactivity are the ultraviolet (UV) photons and the chemically reactive species. In this paper, in order to optimize the UV radiation and reactive species generation efficiency, the plasma was generated by a dielectric barrier discharge driven by unipolar submicrosecond square pulses. To keep the discharge …
Beam-Helicity Asymmetries In Double-Charged-Pion Photoproduction On The Proton, H. Bagdasaryan, M. Bektasoglu, S. Bültmann, Gail Dodge, N. Guler, C. E. Hyde-Wright, H. G. Juengst, A. Klein, S. E. Kuhn, L. M. Qin, W. Roberts, F. Sabatié, S. Tkachenko, L. B. Weinstein, J. Yun, J. Zhang, Et Al., Clas Collaboration
Beam-Helicity Asymmetries In Double-Charged-Pion Photoproduction On The Proton, H. Bagdasaryan, M. Bektasoglu, S. Bültmann, Gail Dodge, N. Guler, C. E. Hyde-Wright, H. G. Juengst, A. Klein, S. E. Kuhn, L. M. Qin, W. Roberts, F. Sabatié, S. Tkachenko, L. B. Weinstein, J. Yun, J. Zhang, Et Al., Clas Collaboration
Physics Faculty Publications
Beam-helicity asymmetries for the two-pion-photoproduction reaction 𝛾⃗p → p π+π- have been studied for the first time in the resonance region for center-of-mass energies between 1.35 and 2.30 GeV. The experiment was performed at Jefferson Lab with the CEBAF Large Acceptance Spectrometer using circularly polarized tagged photons incident on an unpolarized hydrogen target. Beam-helicity-dependent angular distributions of the final-state particles were measured. The large cross-section asymmetries exhibit strong sensitivity to the kinematics and dynamics of the reaction. The data are compared with the results of various phenomenological model calculations, and show that these models currently do not …
Two-Loop Bethe Logarithms For Higher Excited S Levels, Ulrich D. Jentschura
Two-Loop Bethe Logarithms For Higher Excited S Levels, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
Processes mediated by two virtual low-energy photons contribute quite significantly to the energy of hydrogenic S states. The corresponding level shift is of the order of ( α / π )2 ( Z α )6 mec2 and may be ascribed to a two-loop generalization of the Bethe logarithm. For 1 S and 2 S states, the correction has recently been evaluated by Pachucki and Jentschura [Phys. Rev. Lett. 91, 113005 (2003)]. Here, we generalize the approach to higher excited S states, which in contrast to the 1 S and 2 S states can decay to …
Electron Self-Energy For Higher Excited S Levels, Ulrich D. Jentschura, Peter J. Mohr
Electron Self-Energy For Higher Excited S Levels, Ulrich D. Jentschura, Peter J. Mohr
Physics Faculty Research & Creative Works
A nonperturbative numerical evaluation of the one-photon electron self-energy for the 3S and 4S states with charge numbers Z=1 to 5 is described. The numerical results are in agreement with known terms in the expansion of the self-energy in powers of Zα.
Self-Energy Correction To The Two-Photon Decay Width In Hydrogenlike Atoms, Ulrich D. Jentschura
Self-Energy Correction To The Two-Photon Decay Width In Hydrogenlike Atoms, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
We investigate the guage invariance of the leading logarithmic radiative correction to the two-photon decay width in hydrogenlike atoms, was investigated. The effective treatment of the correction using a Lamb-shift led to the equivalent results in both the length and velocity gages. The relevant radiative corrections were found to be related to the energies that entered into the propagator denominators, to the Hamiltonian, to the wave functions, and to the energy conservation condition, that holds between two photons. The results show that the dominant radiative correction to the 2S two-photon decay width is about -2.020 536(α/π)(Zα)2 1n[(Zα)-2] …
Inclusive Photoproduction Of Lepton Pairs In The Parton Model, A. Psaker
Inclusive Photoproduction Of Lepton Pairs In The Parton Model, A. Psaker
Physics Faculty Publications
In the framework of the QCD parton model, we study unpolarized scattering of high energy real photons from a proton target into lepton pairs and a system of hadrons. For a given parametrization of parton distributions in the proton, we calculate the cross section of this process and show the cancellation of the interference terms.
Complete Angular Distribution Measurements Of Two-Body Deuteron Photodisintegration Between 0.5 And 3 Gev, H. Bagdasaryan, H. Bektasoglu, G. E. Dodge, T. A. Forest, C. E. Hyde-Wright, A. Klein, A. V. Klimenko, S. E. Kuhn, F. Sabatié, S. Stepanyan, L. B. Weinstein, J. Yun, Et Al., The Clas Collaboration
Complete Angular Distribution Measurements Of Two-Body Deuteron Photodisintegration Between 0.5 And 3 Gev, H. Bagdasaryan, H. Bektasoglu, G. E. Dodge, T. A. Forest, C. E. Hyde-Wright, A. Klein, A. V. Klimenko, S. E. Kuhn, F. Sabatié, S. Stepanyan, L. B. Weinstein, J. Yun, Et Al., The Clas Collaboration
Physics Faculty Publications
Nearly complete angular distributions of the two-body deuteron photodisintegration differential cross section have been measured using the CEBAF Large Acceptance Spectrometer detector and the tagged photon beam at the Thomas Jefferson National Accelerator Facility. The data cover photon energies between 0.5 and 3.0 GeV and center-of-mass proton scattering angles 10°–160°. The data show a persistent forward-backward angle asymmetry over the explored energy range, and are well described by the nonperturbative quark gluon string model.
Effect Of Kerr Nonlinearity On Defect Lasing Modes In Weakly Disordered Photonic Crystals, Boyang Liu, Alexey Yamilov, Hui Cao
Effect Of Kerr Nonlinearity On Defect Lasing Modes In Weakly Disordered Photonic Crystals, Boyang Liu, Alexey Yamilov, Hui Cao
Physics Faculty Research & Creative Works
We studied the effect of Kerr nonlinearity on lasing in defect modes of weakly disordered photonic crystals. Our time-independent calculation based on self-consistent nonlinear transfer matrix method shows that Kerr nonlinearity modifies both frequencies and quality factors of defect modes. We also used a time-dependent algorithm to investigate the dynamic nonlinear effect. Under continuous pumping, the spatial sizes and intensities of defect lasing modes are changed by Kerr nonlinearity. Such changes are sensitive to the nonlinear response time.