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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 145 records · Page 8
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DOE OSTI2012

On the possibility of an experiment on 'nonlocality' of electrodynamics

It has been known since the 19th century that a circularly polarised electromagnetic wave carries an angular momentum. A simple experiment (Righi, 1882) apparently indicates that the angular momentum is distributed over the entire cross section of the beam. According to some modern ideas, the angular momentum of the beam with the given polarisation is localised near the beam 'surface' and represents a spin of photons, while the energy in the beam is distributed throughout its cross section, which is inconsistent with the principle of locality. For the experimental determination of the localisation of the angular momentum, we propose a new scheme, in which we study the interference pattern of two coherent circularly polarised beams. Each beam first passes through a half-wave plate, one of the plates being divided into two coaxial parts. With (manual) rotation of one parts of the plate we change the frequency of the light passing through it: the plate absorbs the momentum and, therefore, work is done. This change in frequency should cause a movement of the interference fringes and show the distribution of the angular momentum over the beam cross section. (light polarisation)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

The momentum of an electromagnetic wave inside a dielectric

The problem of assigning a momentum to an electromagnetic wave packet propagating inside an insulator has become known under the name of the Abraham–Minkowski controversy. In the present paper we re-examine this issue making the hypothesis that the forces exerted on an insulator by an electromagnetic field do not distinguish between polarization and free charges. Under this assumption we show that the Abraham expression for the radiation mechanical momentum is highly favored. -- Highlights: •We discuss an approximation to treat electrodynamics of a dielectric material. •We support the Abraham form for the electromagnetic momentum. •We deduce Snell’s law from the conservation of the Abraham momentum. •We show how to deal with the electric field discontinuity at the dielectric boundary.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Complex equations of motion for a body under gravitational influence by using a nine-parameter space–time bundle with the structural group SO(3,C)

We give equations of motion of a body under gravitational influence using a model which employs nonlinear connection adapted to 3+3+3-dimensional bundle. It is analogous to the corresponding 3+1 model with nonlinear connection in Minkowski spacetime. The equations of motion are simple complex equations whose real part gives the equations of motion previously obtained in the 3+1 model with nonlinear connection in Minkowski spacetime. They lead to the same predictions as the General Relativity, which are experimentally verified. The imaginary part of the equations of motion gives the total precession of a gyroscope (geodetic precession and frame dragging). The complex equations of motion can be used also in electrodynamics. In this case, the imaginary part corresponds to the Lorentz force, while the real part leads to the angular velocity of an electron in a magnetic field. It is obtained Ω-vector =(e/(mc)) H-vector (if E-vector =0), which fits well with the observations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

SL(2,R) duality-symmetric action for electromagnetic theory with electric and magnetic sources

For the SL(2,R) duality-invariant generalization of Maxwell electrodynamics in the presence of both electric and magnetic sources, we formulate a local, manifestly duality-symmetric, Zwanziger-type action by introducing a pair of four-potentials A{sup μ} and B{sup μ} in a judicious way. On the two potentials A{sup μ} and B{sup μ} the SL(2,R) duality transformation acts in a simple linear manner. In quantum theory including charged source fields, this action can be recast as a SL(2,Z)-invariant action. Also given is a Zwanziger-type action for SL(2,R) duality-invariant Born–Infeld electrodynamics which can be important for D-brane dynamics in string theory. -- Highlights: •We formulate a local, manifestly duality-symmetric, Zwanziger-type action. •Maxwell electrodynamics is generalized to include dilaton and axion fields. •SL(2,R) symmetry is manifest. •We formulate a local, manifestly duality-symmetric, nonlinear Born–Infeld action with SL(2,R) symmetry.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Simulation of a Radio-Frequency Photogun for the Generation of Ultrashort Beams

A radio-frequency photogun for the generation of ultrashort electron beams to be used in fast electron diffractoscopy, wakefield acceleration experiments, and the design of accelerating structures of the millimeter range is modeled. The beam parameters at the photogun output needed for each type of experiment are determined. The general outline of the photogun is given, its electrodynamic parameters are calculated, and the accelerating field distribution is obtained. The particle dynamics is analyzed in the context of the required output beam parameters. The optimal initial beam characteristics and field amplitudes are chosen. A conclusion is made regarding the obtained beam parameters.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Non-perturbative aspects of particle acceleration in non-linear electrodynamics

We undertake an investigation of particle acceleration in the context of non-linear electrodynamics. We deduce the maximum energy that an electron can gain in a non-linear density wave in a magnetised plasma, and we show that an electron can “surf” a sufficiently intense Born-Infeld electromagnetic plane wave and be strongly accelerated by the wave. The first result is valid for a large class of physically reasonable modifications of the linear Maxwell equations, whilst the second result exploits the special mathematical structure of Born-Infeld theory.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2026

Quantum simulation of QED in Coulomb gauge

A recent work considered quantum simulation of Quantum Electrodynamics on a lattice in the Coulomb gauge with gauge degrees of freedom represented in the occupation basis in momentum space. In this work, we consider the more efficient representation of the gauge degrees of freedom in field basis in position space and develop a quantum algorithm for real-time simulation. We show that the continuum Coulomb gauge Hamiltonian is equivalent to the temporal gauge Hamiltonian when acting on physical states consisting of fermion and transverse gauge fields. The Coulomb gauge Hamiltonian is discretized by using the Green’s function of the discrete Laplacian operator under the Dirichlet boundary conditions. Both the continuum Coulomb gauge Hamiltonian and the discretized one proposed here guarantee that the unphysical longitudinal gauge fields are decoupled and commute with the corresponding Hamiltonian. Thus there is no need to impose any constraint. The local gauge field basis and the canonically conjugate variable basis are swapped efficiently using the quantum Fourier transform. We prove that the qubit cost to represent physical states and the gate count for real-time simulation scale polynomially with the lattice size, energy, time, accuracy, and Hamiltonian parameters in lattice units. The gate cost here for implementing the time evolution of the gauge field is reduced at least by a factor on the order of 10 8 for modest lattice size and accuracy level compared with the previous work.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

A model of nonlinear electrodynamics

A new model of nonlinear electrodynamics with two parameters is investigated. We also consider a model with one dimensional parameter. It was shown that the electric field of a point-like charge is not singular at the origin and there is the finiteness of the static electric energy of point-like charged particle. We obtain the canonical and symmetrical Belinfante energy–momentum tensors and dilatation currents. It is demonstrated that the dilatation symmetry and dual symmetry are broken in the models suggested. We have calculated the static electric energy of point-like particles.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

Finding quantum effects in strong classical potentials

The long-standing challenge to describing charged particle dynamics in strong classical electromagnetic fields is how to incorporate classical radiation, classical radiation reaction and quantized photon emission into a consistent unified framework. The current, semiclassical methods to describe the dynamics of quantum particles in strong classical fields also provide the theoretical framework for fundamental questions in gravity and hadron–hadron collisions, including Hawking radiation, cosmological particle production and thermalization of particles created in heavy-ion collisions. However, as we show, these methods break down for highly relativistic particles propagating in strong fields. They must therefore be improved and adapted for the description of laser–plasma experiments that typically involve the acceleration of electrons. Theory developed from quantum electrodynamics, together with dedicated experimental efforts, offer the best controllable context to establish a robust, experimentally validated foundation for the fundamental theory of quantum effects in strong classical potentials.

Physics↗
DOE OSTI2015

Surface participation and dielectric loss in superconducting qubits

We study the energy relaxation times (T{sub 1}) of superconducting transmon qubits in 3D cavities as a function of dielectric participation ratios of material surfaces. This surface participation ratio, representing the fraction of electric field energy stored in a dissipative surface layer, is computed by a two-step finite-element simulation and experimentally varied by qubit geometry. With a clean electromagnetic environment and suppressed non-equilibrium quasiparticle density, we find an approximately proportional relation between the transmon relaxation rates and surface participation ratios. These results suggest dielectric dissipation arising from material interfaces is the major limiting factor for the T{sub 1} of transmons in 3D circuit quantum electrodynamics architecture. Our analysis also supports the notion of spatial discreteness of surface dielectric dissipation.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Electromagnetic fields and potentials generated by massless charged particles

We provide for the first time the exact solution of Maxwell’s equations for a massless charged particle moving on a generic trajectory at the speed of light. In particular we furnish explicit expressions for the vector potential and the electromagnetic field, which were both previously unknown, finding that they entail different physical features for bounded and unbounded trajectories. With respect to the standard Liénard–Wiechert field the electromagnetic field acquires singular δ-like contributions whose support and dimensionality depend crucially on whether the motion is (a) linear, (b) accelerated unbounded, (c) accelerated bounded. In the first two cases the particle generates a planar shock-wave-like electromagnetic field traveling along a straight line. In the second and third cases the field acquires, in addition, a δ-like contribution supported on a physical singularity-string attached to the particle. For generic accelerated motions a genuine radiation field is also present, represented by a regular principal-part type distribution diverging on the same singularity-string. - Highlights: • First exact solution of Maxwell’s equations for massless charges in arbitrary motion. • Explicit expressions of electromagnetic fields and potentials. • Derivations are rigorous and based on distribution theory. • The form of the field depends heavily on whether the motion is bounded or unbounded. • The electromagnetic field contains unexpected Dirac-delta-function contributions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

Superadiabatic scheme for optimizing the fast generation of tree-type 3D entanglement

High-dimensional entanglement has more superior security than qubit entanglement. Recently, adiabatic and fast-adiabatic schemes for generating a novel three-dimensional (3D) entanglement, tree-type 3D entanglement, were proposed. However, the previous schemes have their experimental defects, respectively. Here we give a superadiabatic scheme for optimizing the generation of tree-type 3D entanglement. Adequate numerical simulations prove that the scheme is not only fast, effective and robust, but also highly feasible in experiment. - Highlights: • The scheme for generating tree-type 3D entanglement is not only fast but also robust against the variation in the control parameters and decoherence induced by atomic spontaneous emissions and photon leakages from the cavity-fiber system. • The designed driving pulses are experimentally feasible Gaussian pulses which can reduce experimental difficulties. • The Hamiltonian used to speed up generating tree-type 3D entanglement is of the same form as the original Hamiltonian, which will greatly enhances the experimental feasibility of the scheme.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Noncommutative effects on holographic superconductors with power Maxwell electrodynamics

The matching method is employed to analytically investigate the properties of holographic superconductors in higher dimensions in the framework of power Maxwell electrodynamics taking into account the effects of spacetime noncommutativity. The relationship between the critical temperature and the charge density and the value of the condensation operator is obtained first. The Meissner like effect is then studied. The analysis indicates that larger values of the noncommutative parameter and the parameter q appearing in the power Maxwell theory make the condensate difficult to form. The critical magnetic field however increases with increase in the noncommutative parameter θ.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Absolute photoluminescence intensity in thin film solar cells

A calculation is presented for the direct conversion of a measured luminescence signal to the implied open circuit voltage. The effects of re-absorption, spectral dependence, and interference with front and back interfaces are all included, so long as the optical properties of the structure are known. The method is validated through a comparison of the terminal open-circuit voltage with the photoluminescence intensity of Cu(In,Ga)Se 2 solar cells, each as a function of illumination intensity.

14 SOLAR ENERGY↗
DOE OSTI2021

Laser-induced electron diffraction of the ultrafast umbrella motion in ammonia

Visualizing molecular transformations in real-time requires a structural retrieval method with Ångström spatial and femtosecond temporal atomic resolution. Imaging of hydrogen-containing molecules additionally requires an imaging method sensitive to the atomic positions of hydrogen nuclei, with most methods possessing relatively low sensitivity to hydrogen scattering. Laser-induced electron diffraction (LIED) is a table-top technique that can image ultrafast structural changes of gas-phase polyatomic molecules with sub-Ångström and femtosecond spatiotemporal resolution together with relatively high sensitivity to hydrogen scattering. Here, we image the umbrella motion of an isolated ammonia molecule (NH3) following its strong-field ionization. Upon ionization of a neutral ammonia molecule, the ammonia cation (NH3+) undergoes an ultrafast geometrical transformation from a pyramidal (ΦHNH=107°) to planar (ΦHNH=120°) structure in approximately 8 femtoseconds. Using LIED, we retrieve a near-planar (ΦHNH=117 ± 5°) field-dressed NH3+ molecular structure 7.8−9.8 femtoseconds after ionization. Our measured field-dressed NH3+ structure is in excellent agreement with our calculated equilibrium field-dressed structure using quantum chemical ab initio calculations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Realistic simulations of spin squeezing and cooperative coupling effects in large ensembles of interacting two-level systems

We describe an efficient numerical method for simulating the dynamics of interacting spin ensembles in the presence of dephasing and decay. The method builds on the discrete truncated Wigner approximation for isolated systems, which combines the mean-field dynamics of a spin ensemble with a Monte Carlo sampling of discrete initial spin values to account for quantum correlations. Here we show how this approach can be generalized for dissipative spin systems by replacing the deterministic mean-field evolution by a stochastic process, which describes the decay of coherences and populations while preserving the length of each spin. We demonstrate the application of this technique for simulating nonclassical spin-squeezing effects or the dynamics and steady states of cavity QED models with 10 5 interacting two-level systems. This opens up the possibility to perform accurate real-scale simulations of a diverse range of experiments in quantum optics or with solid-state spin ensembles under realistic laboratory conditions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

QED Based Calculation of the Fine Structure Constant

Quantum electrodynamics is complex and its associated mathematics can appear overwhelming for those not trained in this field. Here, semi-classical approaches are used to obtain a more intuitive feel for what causes electrostatics, and the anomalous magnetic moment of the electron. These intuitive arguments lead to a possible answer to the question of the nature of charge. Virtual photons, with a reduced wavelength of λ, are assumed to interact with isolated electrons with a cross section of πλ 2 . This interaction is assumed to generate time-reversed virtual photons that are capable of seeking out and interacting with other electrons. This exchange of virtual photons between particles is assumed to generate and define the strength of electromagnetism. With the inclusion of near-field effects the model presented here gives a fine structure constant of ~1/137 and an anomalous magnetic moment of the electron of ~0.00116. These calculations support the possibility that near-field corrections are the key to understanding the numerical value of the dimensionless fine structure constant.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Broadband filters for abatement of spontaneous emission in circuit quantum electrodynamics

The ability to perform fast, high-fidelity readout of quantum bits (qubits) is essential to the goal of building a quantum computer. However, coupling a fast measurement channel to a superconducting qubit typically also speeds up its relaxation via spontaneous emission. Here, we use impedance engineering to design a filter by which photons may easily leave the resonator at the cavity frequency but not at the qubit frequency. We implement this broadband filter in both an on-chip and off-chip configuration.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗