Search results for "electrodynamics"
showing 10 items of 820 documents
Nuclear ground-state properties in a relativistic Meson-Field theory
1986
We investigate the ability of a relativistic Mean-Field theory to reproduce nuclear ground state properties by an exhaustive fit to experimental data. We find that the bulk properties of nuclei from16O to208Pb can be adjusted very well. There remain problems with level density and fluctuations in the charge density similar as in fits using the conventional Skyrme Hartree-Fock model.
Spontaneous fission lifetimes from the minimization of self-consistent collective action
2013
The spontaneous fission lifetime of 264Fm has been studied within nuclear density functional theory by minimizing the collective action integral for fission in a two-dimensional quadrupole collective space representing elongation and triaxiality. The collective potential and inertia tensor are obtained self-consistently using the Skyrme energy density functional and density-dependent pairing interaction. The resulting spontaneous fission lifetimes are compared with the static result obtained with the minimum-energy pathway. We show that fission pathways strongly depend on assumptions underlying collective inertia. With the non-perturbative mass parameters, the dynamic fission pathway become…
Multipole modes in deformed nuclei within the finite amplitude method
2015
Background: To access selected excited states of nuclei, within the framework of nuclear density functional theory, the quasiparticle random phase approximation (QRPA) is commonly used. Purpose: We present a computationally efficient, fully self-consistent framework to compute the QRPA transition strength function of an arbitrary multipole operator in axially-deformed superfluid nuclei. Methods: The method is based on the finite amplitude method (FAM) QRPA, allowing fast iterative solution of QRPA equations. A numerical implementation of the FAM-QRPA solver module has been carried out for deformed nuclei. Results: The practical feasibility of the deformed FAM module has been demonstrated. I…
Triangle amplitude with off-shell CoulombTmatrix for exchange reactions in atomic and nuclear physics
1996
The lowest-order rescattering contribution (triangle amplitude) in three-body models of exchange reactions with charged particles contains the off-shell two-body T matrix describing the intermediate-state Coulomb scattering of charged subsystems. General properties of the exact exchange triangle amplitude, when the incoming and outgoing particles are on the energy shell, are derived. This includes the analytic behavior, i.e., the positions and characters of its leading singularities, in the cos\ensuremath{\vartheta} plane, where \ensuremath{\vartheta} is the scattering angle, in the vicinity of the forward- and backward-scattering directions. Since for computational reasons the Coulomb T ma…
The Usefulness of Lie Brackets: From Classical and Quantum Mechanics to Quantum Electrodynamics
2020
We know that in Hamiltonian systems a dynamic function f(q, p) develops in time according to
Simulating open quantum systems with trapped ions
2005
This paper focuses on the possibility of simulating the open system dynamics of a paradigmatic model, namely the damped harmonic oscillator, with single trapped ions. The key idea consists in using a controllable physical system, i.e. a single trapped ion interacting with an engineered reservoir, to simulate the dynamics of other open systems usually difficult to study. The exact dynamics of the damped harmonic oscillator under very general conditions is firstly derived. Some peculiar characteristic of the system’s dynamics are then presented. Finally a way to implement with trapped ion the specific quantum simulator of interest is discussed.
Elements of Quantum Electrodynamics and Weak Interactions
2013
Quantum field theory in its application to electroweak and strong interactions has two rather different facets: A pragmatic, empirical one, and an algebraic, systematical one. The pragmatic approach consists in a set of rules and formal calculational procedures which are extremely successful in their application to concrete physical processes, but rest on mathematically shaky ground. The mathematically rigorous approach, in turn, is technically difficult and not very useful, from a practical point of view, for reaching results which can be compared with phenomenology. Generally speaking, quantum field theory quickly becomes rather technical if one wants to understand it in some depth, and g…
Critical behavior with dramatic enhancement of modulational instability gain in fiber systems with periodic variation dispersion
2008
International audience; We analyze modulational instability (MI) of light waves in fiber systems with periodically varying dispersion. The dispersion fluctuation generates special waves, called nonconventional MI sidebands, which are shown to be highly sensitive to two fundamental system parameters. The first one is the average dispersion of the system. Surprisingly, the second parameter turns out to be the mean value of the dispersion coefficients of the two types of fibers of the system, which is then called “central dispersion.” These two parameters are used to control and optimize the MI process. In particular, we establish the existence of a critical region of the central dispersion at…
Supercontinuum to solitons: New nonlinear structures in fiber propagation
2010
We review our recent work in the field of optical rogue wave physics and applications. Beginning from a brief survey of the well-known noise and incoherence processes in optical fiber supercontinuum generation, we trace the links to recent developments in studying the emergence of high contrast localised breather structures in both spontaneous and induced nonlinear instabilities. In the latter case, we discuss our recent measurements that have reported the experimental observation of the Peregrine soliton, a unique class of rational soliton predicted to exist over 25 years ago and never previously observed.
Nonlinear dynamics of a semilinear photorefractive oscillator
2001
The experimental study of the dynamics of an empty coherent semilinear photorefractive oscillator is reported. It is shown that starting from a certain coupling strength the oscillation occurs with two frequencies shifted symmetrically with respect to the frequency of the pump wave. The threshold of bifurcation in oscillation spectrum depends on pump intensity ratio.