Search results for "quantum electrodynamics"
showing 10 items of 809 documents
Mean-Field Calculation Based on Proton-Neutron Mixed Energy Density Functionals
2015
We have performed calculations based on the Skyrme energy density functional (EDF) that includes arbitrary mixing between protons and neutrons. In this framework, single-particle states are generalized as mixtures of proton and neutron components. The model assumes that the Skyrme EDF is invariant under the rotation in isospin space and the Coulomb force is the only source of the isospin symmetry breaking. To control the isospin of the system, we employ the isocranking method, which is analogous to the standard cranking approach used for describing high-spin states. Here, we present results of the isocranking calculations performed for the isobaric analog states in A = 40 and A = 54 nuclei.
Detuning-induced robustness of a three-state Landau-Zener model against dissipation
2019
A three-state system subjected to a time-dependent Hamiltonian whose bare energies undergo one or more crossings, depending on the relevant parameters, is considered, also taking into account the role of dissipation in the adiabatic following of the Hamiltonian eigenstates. Depending on the fact that the bare energies are equidistant or not, the relevant population transfer turns out to be very sensitive to the environmental interaction or relatively robust. The physical mechanisms on the basis of this behavior are discussed in detail.
Particle in Harmonic E-Field E ( t ) = E sin ω 0 t $$E(t)= E \sin \omega _0 t$$ ; Schwinger–Fock Proper-Time Method
2020
Since the Green’s function of a Dirac particle in an external field, which is described by a potential Aμ(x), is given by
Analytic behavior of the QED polarizability function at finite temperature
2012
We revisit the analytical properties of the static quasi-photon polarizability function for an electron gas at finite temperature, in connection with the existence of Friedel oscillations in the potential created by an impurity. In contrast with the zero temperature case, where the polarizability is an analytical function, except for the two branch cuts which are responsible for Friedel oscillations, at finite temperature the corresponding function is not analytical, in spite of becoming continuous everywhere on the complex plane. This effect produces, as a result, the survival of the oscillatory behavior of the potential. We calculate the potential at large distances, and relate the calcul…
Symmetry-based canonical dressing of a bidimensionally trapped and laser-driven ion
2001
Abstract We present a detailed and exact construction of a unitary operator accomplishing the diagonalization of an effective quadratic radiation-matter interaction model describing a bidimensionally trapped and appropriately laser-driven ion. The possibility of applying the same mathematical method to other effective radiation-matter interaction model is briefly put into evidence.
Unitary decoupling treatment of a quadratic bimodal cavity quantum electrodynamics model
2013
We consider a two-photon quantum model of radiation–matter interaction between a single two-level atom and a degenerate bimodal high-Q cavity field. Within this tripartite system, the explicit construction of two collective radiation modes, one of which is freely evolving and the other one quadratically coupled to the matter subsystem, is reported. The meaning and advantages of such a decoupling treatment are carefully discussed.
The Modelling of Cell Membrane Electrodynamics
2013
Main electrical processes in cells are defined by membranes. The membrane maintains a biochemical environment inside the cell that differs from the outside one, keeping the electrical potential negative inside the cell and organizing the selective transport across the surface. In the paper, it is attempted to explain the cell membrane electrodynamics using modelling experiments with magnetic dipoles. It is shown that the membrane has a definite symmetry or handenness. In addition, a characteristic mechanism of the excited state physics is given. The modelling experiments have also shown that a membrane with different symmetry can exist. Since the electrical processes in these cases are diff…
Metal-Insulator Transition of Solid Hydrogen by the Antisymmetric Shadow Wave Function
2016
We revisit the pressure-induced metal-insulator-transition of solid hydrogen by means of variational quantum Monte Carlo simulations based on the antisymmetric shadow wave function. In order to facilitate studying the electronic structure of large-scale fermionic systems, the shadow wave function formalism is extended by a series of technical improvements, such as a revised optimization method for the employed shadow wave function and an enhanced treatment of periodic systems with long-range interactions. It is found that the superior accuracy of the antisymmetric shadow wave function results in a significantly increased transition pressure.
Cavity-based architecture to preserve quantum coherence and entanglement
2015
Quantum technology relies on the utilization of resources, like quantum coherence and entanglement, which allow quantum information and computation processing. This achievement is however jeopardized by the detrimental effects of the environment surrounding any quantum system, so that finding strategies to protect quantum resources is essential. Non-Markovian and structured environments are useful tools to this aim. Here we show how a simple environmental architecture made of two coupled lossy cavities enables a switch between Markovian and non-Markovian regimes for the dynamics of a qubit embedded in one of the cavity. Furthermore, qubit coherence can be indefinitely preserved if the cavit…
Propagating single photons from an open cavity: Description from universal quantization
2022
Over the last decades, quantum optics has evolved from high quality factor cavities in the early experiments toward new cavity designs involving leaky modes. Despite very reliable models, in the concepts of cavity quantum electrodynamics, photon leakage is most of the time treated phenomenologically. Here, we take a different approach, and starting from first principles, we define an inside-outside representation which is derived from the original true-mode representation, in which one can determine effective Hamiltonian and Poynting vector. Contrary to the phenomenological model, they allow a full description of a leaking single photon produced in the cavity and propagating in free space. …