Showing papers on "Electromagnetic field published in 1987"
TL;DR: Interactions which couple one mode amplitude to the square of another convert this type of squeezing into normal squeezing.
Abstract: Operators are defined which correspond to the real and imaginary parts of the square of the field amplitude. These operators obey an uncertainty relation. Squeezing with respect to these operators is defined and minimum uncertainty states are discussed. A number of nonlinear optical processes are examined and shown to produce this effect. Interactions which couple one mode amplitude to the square of another convert this type of squeezing into normal squeezing. An example of such an interaction is given.
359 citations
TL;DR: Electromagnetic fields with photon-number fluctuation reduced below the standard quantum limit have been generated in a constant-current\char21{}driven semiconductor laser based on a new principle of high impedance suppression for pump-amplitude fluctuation in a highly saturated laser oscillator.
Abstract: Electromagnetic fields with photon-number fluctuation reduced below the standard quantum limit have been generated in a constant-current--driven semiconductor laser. The generation is based on a new principle of high impedance suppression for pump-amplitude fluctuation in a highly saturated laser oscillator. The observed noise level is 7.3% (31% after correction for detection quantum efficiency) in power below the standard quantum limit in the entire frequency range between 350 and 450 MHz.
266 citations
TL;DR: In this paper, the authors show that the electromagnetic field state produced by degenerate parametric downconversion in a subthreshold optical parametric oscillator is a state of minimum uncertainty.
Abstract: Squeezed states of the electromagnetic field are generated by degenerate parametric downconversion in a subthreshold optical parametric oscillator. Reductions in photocurrent noise greater than 60% (-4 dB) below the limit set by the vacuum fluctuations of the field are observed in a balanced homodyne detector. A quantitative comparison with theory suggests that the observed noise reductions result from a field that in the absence of avoidable linear attenuation would be squeezed more than tenfold. A degree of squeezing of approximately fivefold is inferred for the actual field emitted through one mirror of the optical parametric oscillator. An explicit demonstration of the Heisenberg uncertainty principle for the electromagnetic field is made from the measurements, which show that the field state produced by the downconversion process is a state of minimum uncertainty.
258 citations
Patent•
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05 May 1987
TL;DR: A catheter for insertion into a body cavity, comprising a tubular shaft formed with a passageway extending longitudinally there through closed at one end and open at the opposite end, is described in this article.
Abstract: A catheter for insertion into a body cavity, comprises a tubular shaft formed with a passageway extending longitudinally therethrough closed at one end and open at the opposite end and a probe removably received within the passageway through its open end The probe includes a temperature sensor for sensing the heat produced by a heating applicator applied to an adjacent area of the body The heating applicator includes a microwave antenna producing an electromagnetic field for heating the body tissue adjacent to the body cavity, and the sensor including an electromagnetic field detector for detecting the peak of the electromagnetic field produced by the applicator antenna
253 citations
TL;DR: In this paper, an oscillatory distribution in photon number was found, and the conditions which produce them were investigated in the course of an investigation of sudden transitions, based on the semi-classical description of a quantum state as motion of a representative point in the phase space defined by oscillator coordinate and oscillator momentum.
Abstract: The drive for both noise-free message transmission1,2 and high precision gravity wave detection3,4 has stimulated immense effort on a key element, a squeezed state5,6 of the electromagnetic field. Such non-classical states have been investigated theoretically in great detail1–7 and have now been realized experimentally in four laboratories in the United States8–13. However, nowhere in the literature have we been able to find the striking feature of a squeezed state which we report here: an oscillatory distribution in photon number14,15. These oscillations, and the conditions which produce them, came to light in the course of an investigation of sudden transitions16 (the Franck–Condon effect in molecular physics17,18) based on the semi-classical description of a quantum state19 as motion of a representative point in the phase space defined by oscillator coordinate and oscillator momentum.
224 citations
TL;DR: In this paper, the authors considered a general field of electromagnetic waves of a single frequency and identified the salient structurally stable features of the three-dimensional pattern of polarization, which is applicable even when the constituent plane waves are travelling in all directions.
Abstract: The paper considers a general field of electromagnetic waves of a single frequency and identifies the salient structurally stable features of the three-dimensional pattern of polarization. The approach is geometrical rather than analytical, and it differs from previous treatments of this kind by being applicable even when the constituent plane waves are travelling in all directions. Lines and surfaces exist where the electric or magnetic vibration ellipse is singular. The field is divided into right-handed and left-handed regions by \`T surfaces', the electric and magnetic T surfaces not being coincident. Lying in the T surfaces are \`L$^T$ lines' where the vibration is linear, and cutting through the T surfaces are `C$^T$ lines' where the vibration is circular. Both kinds of lines are surrounded by characteristic patterns of vibration ellipses, which provide a singularity index, $\pm$ 1 for L$^T$ and $\pm \frac{1}{2}$ for C$^T$. The analysis is applicable in a cavity, but a loss-free resonating cavity represents a highly degenerate case.
224 citations
TL;DR: The contributions of the scalar massless, neutrino, and electromagnetic fields to the vacuum polarization in the gravitational field of a cosmic string are found.
Abstract: The contributions of the scalar massless, neutrino, and electromagnetic fields to the vacuum polarization in the gravitational field of a cosmic string are found.
171 citations
Patent•
08 Jan 1987
TL;DR: In this paper, an improved method and apparatus of transmitting data signals within a well bore having a string of tubular members suspended within it, employing an electromagnetic field producing means to transmit the signal to a magnetic field sensor, which is capable of detecting constant and time-varying fields, the signal then being conditioned so as to regenerate the data signals before transmission across the subsequent threaded junction by another electromagnetic field generating means and magnetic sensor pair.
Abstract: An improved method and apparatus of transmitting data signals within a well bore having a string of tubular members suspended within it, employing an electromagnetic field producing means to transmit the signal to a magnetic field sensor, which is capable of detecting constant and time-varying fields, the signal then being conditioned so as to regenerate the data signals before transmission across the subsequent threaded junction by another electromagnetic field producing means and magnetic sensor pair.
167 citations
TL;DR: In this paper, explicit type D solutions for nonlinear electrodynamics of Born-Infeld type allowing for the freedom of duality rotations are constructed, which exhaust all solutions within the considered class, under the assumption that the real eigenvectors of the electromagnetic field are aligned along the geodesic and shear free principal null directions.
Abstract: Within nonlinear electrodynamics of Born–Infeld type allowing for the freedom of duality rotations, explicit type D solutions are constructed. The obtained type D solutions, which generalize the charged Taub–NUT (Newman–Unti–Tamburino) metric with λ, exhaust all solutions within the considered class, under the assumption that the real eigenvectors of the electromagnetic field are aligned along the geodesic and shear‐free principal null directions. Various relevant limiting transitions, in particular those of the flat space‐time, are studied in some detail.
165 citations
TL;DR: In this article, the global electrodynamics of a viscous resistive accretion disk around a Schwarzschild black hole with a force-free plasma outside of the disk is worked out, and a global condition is derived which imposes an upper bound on the reaction of the accretion luminosity which can be carried away by the jets.
Abstract: The global electrodynamics of a viscous resistive accretion disk around a Schwarzschild black hole with a force-free plasma outside of the disk is worked out The magnetic field in the disk is assumed to include a well-ordered component The magnetic field and fluid dynamics of the disk are tested, simplifying the induction equation and solving for the flux function and the toroidal magnetic field A Green's function method is used to obtain far-field solutions of the basic electromagnetic field equation for the plasma outside of the disk The solutions are found to include self-collimated electromagnetic jets The overall energy conservation for the disk-jet system is considered, and a global condition is derived which imposes an upper bound on the reaction of the accretion luminosity which can be carried away by the jets 36 references
161 citations
TL;DR: In this paper, the electromagnetic fields associated with a beam splitter having two input arms and two output arms are quantized in terms of the spatial modes of the complete optical system.
01 Jan 1987
TL;DR: Electromagnetic Fields and Critical Phenomena in Cells Exposed to EM Fields: A Review, some Possible Limits on the Minimum Electrical Signals of Biological Significance.
Abstract: Ions and Membrane Surfaces.- Ionic Processes at Membrane Surfaces: The Role of Electrical Double Layers in Electrically Stimulated Ion Transport.- Membrane Transduction of Low Energy Level Fields and the Ca++ Hypothesis.- Electrochemical Kinetics at the Cell Membrane: A Physicochemical Link for Electromagnetic Bioeffects.- Modification of Charge Distribution at Boundaries between Electrically Dissimilar Media.- The Role of the Magnetic Field in the EM Interaction with Ligand Binding.- Cyclotron Resonance in Cell Membranes: The Theory of the Mechanism.- Experimental Evidence for Ion Cyclotron Resonance Mediation of Membrane Transport.- Frequency and Amplitude Dependence of Electric Field Interactions: Electrokinetics and Biosynthesis.- Macromolecules.- The Influence of Surface Charge on Oligomeric Reactions as a Basis for Channel Dynamics.- Internal Electric Fields Generated by Surface Charges and Induced by Visible Light in Bacteriorhodopsin Membranes.- Interaction of Membrane Proteins with Static and Dynamic Electric Fields via Electroconformational Coupling.- Interactions Between Enzyme Catalysis and Non Stationary Electric Fields.- Patterns of Transcription and Translation in Cells Exposed to EM Fields: A Review.- Interaction of Electromagnetic Fields with Genetic Information.- Membrane Matrix.- Transient Aqueous Pores: A Mechanism for Coupling Electric Fields to Bilayer and Cell Membranes.- Electrorotation - The Spin of Cells in Rotating High Frequency Electric Fields.- Membranes, Electromagnetic Fields and Critical Phenomena.- Field Effects in Experimental Bilayer Lipid Membranes and Biomembranes.- Fusogenic Membrane Alterations Induced by Electric Field Pulses.- Integrated Systems.- Some Possible Limits on the Minimum Electrical Signals of Biological Significance.- Electrostatic Fields and their Influence on Surface Structure, Shape and Deformation of Red Blood Cells.- Cell Surface Ionic Phenomena in Transmembrane Signaling to Intracellular Enzyme Systems.- Low Energy Time Varying Electromagnetic Field Interactions with Cellular Control Mechanisms.- The Mechanism of Faradic Stimulation of Osteogenesis.- The Role of Calcium Ions in the Electrically Stimulated Neurite Formation in Vitro.- On the Responsiveness of Elasmobranch Fishes to Weak Electric Fields.- Contributors.
TL;DR: The quantum theory of a microscopic maser operating on a degenerate two-photon transition between levels of the same parity is presented and it is shown that quantum effects may have a substantial influence on the behavior of the maser.
Abstract: We present the quantum theory of a microscopic maser operating on a degenerate two-photon transition between levels of the same parity. We derive both a master equation and a Fokker-Planck equation for this system, and show that quantum effects may have a substantial influence on the behavior of the maser. They modify the oscillation threshold and make external triggering of this maser unnecessary, whereas, according to semiclassical theory, such a triggering is required to start up the maser oscillation. We derive the phase-diffusion properties of the field and show that the diffusion coefficient is complex in this case, its imaginary part being associated with a frequency shift of the field inside the cavity. We show that, in steady state, the photon-number statistics is sub-Poissonian for a wide range of pumping rates.
TL;DR: In this article, an image of the conductivity section of a layered earth can be obtained by simple transformation of step-response electromagnetic data measured in the quasi-static zone, where the variation of the step response as a function of geometry (transmitter and receiver location) is transformed to an equivalent reference depth h, which can be related to the depth of electromagnetic field diffusion.
Abstract: An “imaged” conductivity section of a layered earth can be obtained by simple transformation of step‐response electromagnetic data measured in the quasi‐static zone. This method of data transformation is presented as an alternative to conventional apparent conductivity transformations. At each delay time, the variation of the step response as a function of geometry (transmitter and receiver location) is transformed to an equivalent reference depth h, which can be related to the depth of electromagnetic field diffusion. The behavior of h as a function of delay time is nearly independent of the source‐receiver geometry. The slowness dt/dh divided by the magnetic permeability is almost exactly proportional to the cumulative conductance measured from the surface down to a depth h. Thus we can estimate an apparent conductivity, which we call the “imaged conductivity,” at depth to be d2t/μ0dh2. The cost of this transformation is a fraction of the cost of conventional data inversion, and it does not require an a...
Book•
15 Jan 1987
TL;DR: In this article, the authors apply the variational principles of mechanics to electromagnetic problems, creating a streamlined, practical method for solving electromagnetic field calculations, and explain how it is possible to obtain upper and lower bounds to the equilibrium energy by the dual formulation of the electromagnetic equations' structure, in which the coordinates and momenta are interchanged.
Abstract: This book, first published in 1981, applies the variational principles of mechanics to electromagnetic problems, creating a streamlined, practical method for solving electromagnetic field calculations. The author explains how it is possible to obtain upper and lower bounds to the equilibrium energy by the dual formulation of the electromagnetic equations' structure, in which the coordinates and momenta are interchanged. Other advantages of the dual formulation are considered, and the author provides full details of the basis of the method, an account of Lagrangian mechanics, and a number of fully worked examples.
TL;DR: A 2D electromagnetic version of the direct implicit PIC algorithm has been developed and implemented in the new code AVANTI as discussed by the authors, which runs stably with an arbitrarily large time step and is quite robust with respect to large particle fluctuations that result when plasmas are represented with small numbers of particles per cell.
TL;DR: It is shown that, within the stochastic electrodynamic formulation and at the level of Bohr theory, the ground state of the hydrogen atom can be precisely defined as resulting from a dynamic equilibrium between radiation emitted due to acceleration of the electron in its ground-state orbit and radiation absorbed from zero-point fluctuations of the background vacuum electromagnetic field.
Abstract: We show here that, within the stochastic electrodynamic formulation and at the level of Bohr theory, the ground state of the hydrogen atom can be precisely defined as resulting from a dynamic equilibrium between radiation emitted due to acceleration of the electron in its ground-state orbit and radiation absorbed from zero-point fluctuations of the background vacuum electromagnetic field, thereby resolving the issue of radiative collapse of the Bohr atom.
TL;DR: A broad-band electric field probe, capable of accurately characterizing and quantifying electromagnetic (EM) fields, has been developed at the National Bureau of Standards (NBS) as discussed by the authors.
Abstract: A new broad-band electric-field probe, capable of accurately characterizing and quantifying electromagnetic (EM) fields, has been developed at the National Bureau of Standards (NBS). The probe's 8-mm resistively tapered dipole elements allow measurement of eleetric fields between 1 and 1600 V/m from 1 MHz to 15 GHz, with a flatness of +-2 dB. A mutually orthogonal dipole configuration provides an overall standard deviation in isotropic response, with respect to angle, that is within +-0.3 dB. Both the theoretical and developmental aspects of this prototype electric-field probe are discussed in this paper.
TL;DR: In this article, the thermal spectrum and density of states of dielectric microspheres were evaluated as a first step toward quantizing the electromagnetic field, and it was shown that they obey an asymptotic sum rule.
Abstract: Many recently observed optical properties of dielectric microspheres arise from the fact that they behave as optical cavities with little leakage. The thermal spectrum and the density of states are evaluated for such cavitites as a first step toward quantizing the electromagnetic field. The density of states is shown to obey an asymptotic sum rule. The formalism resolves the apparent contradiction between dissipation (from leakage) and quantization.
TL;DR: In this paper, the authors describe observations of these singularities in two different monochromatic microwave fields and confirm all the theoretically predicted properties of the singularities that could be tested.
Abstract: Electromagnetic waves propagating in free space contain three kinds of singularities called C lines, S surfaces and disclinations. The paper describes observations of these singularities in two different monochromatic microwave fields. The observations confirm all the theoretically predicted properties of the singularities that could be tested. As expected, the singularities were found to be prominent structural features of the fields and in consequence to provide an economical means of characterizing their structure. A notable result is the observation of both right-hand and left-hand C lines in a field that is nominally uniformly left-hand circularly polarized. This is in agreement with the previous assertion that, in general, electromagnetic wavefields contain both right-hand and left-hand polarized regions.
TL;DR: In this paper, the authors present an algorithm for the implicit calculation of the electromagnetic fields used in the full-particle and hybrid modeling of 2D simulation plasmas, which allows for calculations at time steps well in excess of the plasma period and for mesh scales Δξ far exceeding the Debye length.
15 Aug 1987-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, a program package called BEAMTRACE is presented which allows determination of the properties of optical systems for intense ion beams in which space-charge forces must be taken into account.
Abstract: A program package is presented which allows determination of the properties of optical systems for intense ion beams in which space-charge forces must be taken into account. GIOS is based on the algebraic determination of the elements of transfer matrices and allows an automatic optimization of the optical system under consideration. BEAMTRACE is based on the numerical solution of the equations of motion in assumed fields. In both cases the internal space-charge fields are added to the external electromagnetic fields.
TL;DR: In this article, a new static electromagnetic reciprocity principle is presented, extending ordinary resistive reciprocity to the case of nonzero magnetic fields by requiring the magnetic field to be reversed when the reciprocal measurement is made.
Abstract: A new static‐electromagnetic reciprocity principle is presented, extending ordinary resistive reciprocity to the case of nonzero magnetic fields by requiring the magnetic field to be reversed when the reciprocal measurement is made. The principle is supported by measurements on various types of specimens, including those which exhibit the quantum‐Hall effect. A derivation using elementary electromagnetic theory shows that the principle will hold provided only that the specimen is electrically linear (Ohmic), and that the Onsager form for the conductivity tensor applies throughout. The principle has important implications for electrical measurements on semiconductors in applied‐magnetic fields.
TL;DR: In this article, the authors derived the spectrum of spatial modes of the Fabry-Perot cavity and quantized the electromagnetic field in terms of a continuous set of mode creation and destruction operators.
Abstract: The quantum limits on measurements of small changes in the length of a Fabry-Perot cavity are calculated. The cavity is modelled by a pair of dissimilar mirrors oriented perpendicular to a one-dimensional axis of infinite extent. The continuous spectrum of spatial modes of the system is derived, and the electromagnetic field is quantized in terms of a continuous set of mode creation and destruction operators. Coherent state and squeezed vacuum-state excitations of the field are characterized by energy flow, or intensity, variables. The determination of small changes in the cavity length by observations of fringe intensity is considered for schemes in which the cavity is simultaneously excited by coherent and squeezed vacuum-state inputs. The contributions to the limiting resolution from photocount and radiation-pressure length uncertainties are evaluated. These properties of the Fabry-Perot cavity are compared with the corresponding results for the Michelson interferometer.
Book•
01 Jan 1987
TL;DR: The Lagrangian Function of a High-Intensity Electromagnetic Field The Shift of Electron Mass in a High Intensity Field Three-Photon Interaction in a high-intensity Field Radiation Effects and their Enhancement in a HII Electromagnetagnetic Field An S-Matrix of Quantum Electrodynamics with a Pair-Production External Field A Particle in a Static Electrical Field and a Planar Electromagnagnetic Wave Propagating Along the Field The Formation of a e+e-Pair from a Fast Muon/Atom Collision The Influence of
Abstract: Contents: The Lagrangian Function of a High-Intensity Electromagnetic Field The Shift of Electron Mass in a High-Intensity Field Three-Photon Interaction in a High-Intensity Field Radiation Effects and their Enhancement in a High-Intensity Electromagnetic Field An S-Matrix of Quantum Electrodynamics with a Pair-Production External Field A Particle in a Static Electrical Field and a Planar Electromagnetic Wave Propagating Along the Field The Formation of a e+e-Pair from a Fast Muon/Atom Collision The Influence of a Laser Field on the Beta Decay of Nucleii and Other Processes Occurring in the Absence of a Field.
TL;DR: It is suggested that cross-polarization measurement using a null detector can serve as a new method for accurate determination of the center of Gaussian laser beams.
Abstract: Polarization properties of Gaussian laser beams are analyzed in a manner consistent with the Maxwell equations, and expressions are developed for all components of the electric and magnetic field vectors in the beam. It is shown that the transverse nature of the free electromagnetic field demands a nonzero transverse cross-polarization component in addition to the well-known component of the field vectors along the beam axis. The strength of these components in relation to the strength of the principal polarization component is established. It is further shown that the integrated strengths of these components over a transverse plane are invariants of the propagation process. It is suggested that cross-polarization measurement using a null detector can serve as a new method for accurate determination of the center of Gaussian laser beams.
TL;DR: In this paper, the authors considered the two-dimensional problem of oblique scattering by penetrable cylinders of arbitrary cross section made of materials which are linear, lossy, anisotropic and possibly inhomogeneous.
Abstract: The two-dimensional problem of oblique scattering by penetrable cylinders of arbitrary cross section made of materials which are linear, lossy, anisotropic and possibly inhomogeneous is considered. The materials are characterized by arbitrary tensor susceptibilities \bar{x}_{ec} and \bar{x}_{m} . The frequency-domain volume integrodifferential equations satisfied by the electric and magnetic fields and obtained in a previous paper (Part 1) are analyzed numerically. Optimal ordering of the unknowns and transverse electric-transverse magnetic (TE-TM) decomposition in the matrix formulation of the problem are discussed. The cross section of the scatterer is broken down into a triangular mesh. The field components at the vertices of the triangles are the unknowns; within each triangle, each field component is a linear combination of its values at the vertices. Computed field distributions inside the scatterer are found to be in excellent agreement with results obtained by other methods.
TL;DR: In this paper, the time-domain reciprocity theorems of the time convolution and the time correlation type for electromagnetic fields in linear, time-invariant, and locally reacting media are discussed.
Abstract: Time-domain reciprocity theorems of the time-convolution and the time-correlation type for electromagnetic fields in linear, time-invariant, and locally reacting media are discussed. Inhomogeneous, anisotropic, and arbitrarily dispersive, both active and passive, media are included. The analysis is entirely carried out in space-time, without intermediate recourse to the frequency or the wave vector domain. The application to inverse source and inverse constituency (or inverse profiling) problems is briefly indicated.