Search results for "MAGNETIC FIELD"
showing 10 items of 1488 documents
Resonance Dipole-Dipole Interaction Between Two Accelerated Atoms in the Presence of a Reflecting Plane Boundary
2018
We study the resonant dipole-dipole interaction energy between two uniformly accelerated identical atoms, one excited and the other in the ground state, prepared in a correlated {\em Bell-type} state, and interacting with the scalar field or the electromagnetic field nearby a perfectly reflecting plate. We suppose the two atoms moving with the same uniform acceleration, parallel to the plane boundary, and that their separation is constant during the motion. We separate the contributions of vacuum fluctuations and radiation reaction field to the resonance energy shift of the two-atom system, and show that Unruh thermal fluctuations do not affect the resonance interaction, which is exclusivel…
Electromagnetic field fluctuations near a dielectric-vacuum boundary and surface divergences in the ideal conductor limit
2012
We consider the electric and magnetic field fluctuations in the vacuum state in the region external to a half-space filled with a homogeneous non-dissipative dielectric. We discuss an appropriate limit to an ideal metal and concentrate our interest on the renormalized field fluctuations, or equivalently to renormalized electric and magnetic energy densities, in the proximity of the dielectric-vacuum interface. We show that surface divergences of field fluctuations arise at the interface in an appropriate ideal conductor limit, and that our limiting procedure allows to discuss in detail their structure. Field fluctuations close to the surface can be investigated through the retarded Casimir-…
Synthetic electromagnetic knot in a three-dimensional skyrmion
2018
We experimentally simulate a quantum-mechanical particle interacting with knotted electromagnetic fields.
Time-dependent Kohn-Sham approach to quantum electrodynamics
2010
We prove a generalization of the van Leeuwen theorem towards quantum electrodynamics, providing the formal foundations of a time-dependent Kohn-Sham construction for coupled quantized matter and electromagnetic fields. Thereby we circumvent the symmetry-causality problems associated with the action-functional approach to Kohn-Sham systems. We show that the effective external four-potential and four-current of the Kohn-Sham system are uniquely defined and that the effective four-current takes a very simple form. Further we rederive the Runge-Gross theorem for quantum electrodynamics.
Semiclassical geons as solitonic black hole remnants
2013
We find that the end state of black hole evaporation could be represented by non-singular and without event horizon stable solitonic remnants with masses of the order the Planck scale and up to similar to 16 units of charge. Though these objects are locally indistinguishable from spherically symmetric, massive electric (or magnetic) charges, they turn out to be sourceless geons containing a wormhole generated by the electromagnetic field. Our results are obtained by interpreting semiclassical corrections to Einstein's theory in the first-order (Palatini) formalism, which yields second-order equations and avoids the instabilities of the usual (metric) formulation of quadratic gravity. We als…
Multicenter solutions in Eddington-inspired Born-Infeld gravity
2020
We find multicenter (Majumdar-Papapetrou type) solutions of Eddington-inspired Born-Infeld gravity coupled to electromagnetic fields governed by a Born-Infeld-like Lagrangian. We construct the general solution for an arbitrary number of centers in equilibrium and then discuss the properties of their one-particle configurations, including the existence of bounces and the regularity (geodesic completeness) of these spacetimes. Our method can be used to construct multicenter solutions in other theories of gravity.
Dispersion Interactions between Neutral Atoms and the Quantum Electrodynamical Vacuum
2018
Dispersion interactions are long-range interactions between neutral ground-state atoms or molecules, or polarizable bodies in general, due to their common interaction with the quantum electromagnetic field. They arise from the exchange of virtual photons between the atoms, and, in the case of three or more atoms, are not additive. In this review, after having introduced the relevant coupling schemes and effective Hamiltonians, as well as properties of the vacuum fluctuations, we~outline the main properties of dispersion interactions, both in the nonretarded (van der Waals) and retarded (Casimir--Polder) regime. We then discuss their deep relation with the existence of the vacuum fluctuation…
Van der Waals and resonance interactions between accelerated atoms in vacuum and the Unruh effect
2017
We discuss different physical effects related to the uniform acceleration of atoms in vacuum, in the framework of quantum electrodynamics. We first investigate the van der Waals/Casimir-Polder dispersion and resonance interactions between two uniformly accelerated atoms in vacuum. We show that the atomic acceleration significantly affects the van der Waals force, yielding a different scaling of the interaction with the interatomic distance and an explicit time dependence of the interaction energy. We argue how these results could allow for an indirect detection of the Unruh effect through dispersion interactions between atoms. We then consider the resonance interaction between two accelerat…
A Geant4 simulation package for the sage spectrometer
2012
International audience; A comprehensive Geant4 simulation was built for the SAGE spectrometer. The simulation package includes the silicon and germanium detectors, the mechanical structure and the electromagnetic fields present in SAGE. This simulation can be used for making predictions through simulating experiments and for comparing simulated and experimental data to better understand the underlying physics.
High precision hyperfine measurements in Bismuth challenge bound-state strong-field QED
2017
Electrons bound in highly charged heavy ions such as hydrogen-like bismuth 209Bi82+ experience electromagnetic fields that are a million times stronger than in light atoms. Measuring the wavelength of light emitted and absorbed by these ions is therefore a sensitive testing ground for quantum electrodynamical (QED) effects and especially the electron–nucleus interaction under such extreme conditions. However, insufficient knowledge of the nuclear structure has prevented a rigorous test of strong-field QED. Here we present a measurement of the so-called specific difference between the hyperfine splittings in hydrogen-like and lithium-like bismuth 209Bi82+,80+ with a precision that is improve…