arXiv subjects

A. Widom

Publications and source records attributed to A. Widom.

At least 91 records · Page 5Linked to original sources

arXiv2003

Non-Commutative Geometry and Measurements of Polarized Two Photon Coincidence Counts

Employing Maxwell's equations as the field theory of the photon, quantum mechanical operators for spin, chirality, helicity, velocity, momentum, energy and position are derived. The photon ``Zitterbewegung'' along helical paths is explored. The resulting non-commutative geometry of photon position and the quantum version of the Pythagorean theorem is discussed. The distance between two photons in a polarized beam of given helicity is shown to have a discrete spectrum. Such a spectrum should become manifest in measurements of two photon coincidence counts. The proposed experiment is briefly described.

hep-th↗

arXiv2003

Gravitational Wave Detection with Michelson Interferometers

Electromagnetic methods recently proposed for detecting gravitational waves modify the Michelson phase shift analysis (historically employed for special relativity). We suggest that a frequency modulation analysis is more suited to general relativity. An incident photon in the presence of a very long wavelength gravitational wave will have a finite probability of being returned as a final photon with a frequency shift whose magnitude is equal to the gravitational wave frequency. The effect is due to the non-linear coupling between electromagnetic and gravitational waves. The frequency modulation is derived directly from the Maxwell-Einstein equations.

gr-qc↗

arXiv2003

Radiating and Non-Radiating Current Distributions in Quantum Electrodynamics

The notion of ``radiating'' and ``non-radiating'' current sources in classical electrodynamics plays an important role in calculations of direct and inverse electromagnetic scattering problems. Such a decomposition of the current is central for the notion of localized non-radiating electromagnetic modes. A completely quantum electrodynamic view is explored in this work. Photon emission and absorption current sources are classified as being either radiating or non-radiating. This quantum classification corresponds, respectively and exactly, to the notion of ``real'' and ``virtual'' photon processes. Causal properties of both real and virtual electromagnetic fields are discussed.

quant-ph↗

arXiv2003

Electronic Enhancements in the Detection of Gravitational Waves by Metallic Antennae

For mechanical Weber gravitational wave antennae, it is thought that gravity waves are weakly converted into acoustic vibrations. Acoustic vibrations in metals (such as Aluminum) are experimentally known to be attenuated by the creation of electron-hole pairs described via the electronic viscosity. These final state electronic excitations give rise to gravitational wave absorption cross sections which are considerably larger (by four orders of magnitude) than those in previous theories which have not explicitly considered electronic excitations.

gr-qc↗

arXiv2003

The Clausius-Mossotti Phase Transition in Polar Liquids

The conventional Clausius-Mossotti polarization equation of state is known to be unstable for polar liquids having molecules with high polarizability. Room temperature water is an important example. The instability in the polarization equation of state is of the typical loop form requiring an ``equal area'' construction for studying the stable ordered phase. The ordered phase of a Clausius-Mossotti polar liquid then consists of domains each having a net polarization. The polarization may vary in direction from domain to domain. The ordered phases are quite similar to those previously discussed on the basis of Dicke superradiance.

cond-mat.stat-mech↗

arXiv2003

Quantum dissipation induced noncommutative geometry

The quantum statistical dynamics of a position coordinate x coupled to a reservoir requires theoretically two copies of the position coordinate within the reduced density matrix description. One coordinate moves forward in time while the other coordinate moves backward in time. It is shown that quantum dissipation induces, in the plane of the forward and backward motions, a noncommutative geometry. The noncommutative geometric plane is a consequence of a quantum dissipation induced phase interference which is closely analogous to the Aharanov-Bohm effect.

quant-ph↗

arXiv2002

Landau Ghosts and Anti-Ghosts in Condensed Matter and High Density Hadronic Matter

It is observed that the ``ghost'' (originally discovered by Landau in quantum electro-dynamics) and its counterparts in other theories are indeed ubiquitous as they occur in a one-loop approximation to any conventional (unbroken) gauge theory. The mechanism is first exposed in its generality via the Dyson equation and a simple but explicit example in condensed matter is provided through the static Clausius-Mossotti and its dynamic counterpart the Lorenz-Lorentz equation. The physical phase transition phenomenon associated with it is found to be super-radiance. We verify quantitatively that water (and many other polar liquids) are indeed super-radiant at room temperature. In quantum chromo-dynamics on the other hand, we encounter, thanks to asymptotic freedom, an ``anti-ghost'' which is closely associated with color confinement. Thus, in QCD, free quarks and glue exist in a super-radiant phase and hadronic matter in the normal one.

hep-ph↗

arXiv2002

Thermodynamic QED Coherence in Condensed Matter: Microscopic Basis of Thermal Superradiance

Electromagnetic superradiant field coherence exists in a condensed matter system if the electromagnetic field oscillators undergo a mean displacement. Transitions into thermal states with ordered superradiant phases have been shown to theoretically exist in Dicke-Preparata models. The theoretical validity of these models for condensed matter has been called into question due to non-relativistic diamagnetic terms in the electronic Hamiltonian. The microscopic bases of Dicke-Preparata thermal superradiance for realistic macroscopic systems are explored in this work. The impossibility of diaelectric correlations in condensed matter systems (via the Landau-Lifshitz theorem) provides a strong theoretical basis for understanding the physical reality of condensed matter thermodynamic superradiant phases.

cond-mat.stat-mech↗

arXiv2002

Thermal Superradiance and the Clausius-Mossotti Lorentz-Lorenz Equations

Electric polarization phenomena in insulating systems have long been described in mean field theory by the (static) Clausius-Mossotti or (dynamic) Lorentz-Lorenz polarizabilities. It is here shown, in the strong coupling regime, that a thermodynamic phase instability exists in these models. The resulting thermodynamic phase diagram coincides with that obtained from Dicke-Preparata model of thermal superradiance.

cond-mat.stat-mech↗

arXiv2002

Atomic Scale Fractal Dimensionality in Proteins

The soft condensed matter of biological organisms exhibits atomic motions whose properties depend strongly on temperature and hydration conditions. Due to the superposition of rapidly fluctuating alternative motions at both very low temperatures (quantum effects) and very high temperatures (classical Brownian motion regime), the dimension of an atomic ``path'' is in reality different from unity. In the intermediate temperature regime and under environmental conditions which sustain active biological functions, the fractal dimension of the sets upon which atoms reside is an open question. Measured values of the fractal dimension of the sets on which the Hydrogen atoms reside within the Azurin protein macromolecule are reported. The distribution of proton positions was measured employing thermal neutron elastic scattering from Azurin protein targets. As the temperature was raised from low to intermediate values, a previously known and biologically relevant dynamical transition was verified for the Azurin protein only under hydrated conditions. The measured fractal dimension of the geometrical sets on which protons reside in the biologically relevant temperature regime is given by $D=0.65 \pm 0.1$. The relationship between fractal dimensionality and biological function is qualitatively discussed.

cond-mat↗

arXiv2002

Temperature of a Compressed Bubble with Application to Sonoluminescence

The rise in temperature from the adiabatic compression of a bubble is computed in thermodynamic mean field (van der Waals) theory. It is shown that the temperature rise is higher for the noble gas atoms than for more complex gas molecules. The adiabatic temperature rise is shown to be sufficient for producing sonoluminescence via the excited electronic states of the atoms.

cond-mat↗

arXiv2002

Radiation Induced Landau-Lifshitz-Gilbert Damping in Ferromagnets

The Landau-Lifshitz-Gilbert damping coefficient employed in the analysis of spin wave ferromagnetic resonance is related to the electrical conductivity of the sample. The changing magnetization (with time) radiates electromagnetic fields. The electromagnetic energy is then absorbed by the sample and the resulting heating effect describes magnetic dissipative damping. The ferromagnetic resonance relaxation rate theoretically depends on the geometry (shape and size) of the sample as well as temperature in agreement with experiment.

cond-mat.stat-mech↗

arXiv2001

Electric Field Effects and the Experimental Value of the Muon g-2 Anomaly

The electric field corrections to the recently measured muon magnetic moment g-2 anomaly are considered from both the classical (BMT) and the quantum mechanical (Dirac) viewpoints. In both views, we prove that the electric field inducing the horizontal betatron tune does not renormalize the anomaly frequency. With this result kept in mind, the experimental muon magnetic moment anomaly is in closer agreement with standard model predictions than has been previously reported.

hep-ph↗

arXiv2001

Coherent Betatron Oscillation and Induced Errors in the Experimental Determination of the Muon g-2 Factor

Precision measurements of the anomalous magnetic moment of the muon depend on the correct collective mode assignment of the coherent betatron oscillations in the beam. Presently, there is a disagreement between experiment and theory for the horizontal betatron frequency. The discrepancy is here resolved by our computations of electrostatic beam focusing. The correct treatment of the betatron effects renders less likely the need for non-standard model corrections to the muon g-2.

hep-ph↗

arXiv2001

Posture Noise and the Measured Probability to Fall

Experimental evidence is presented connecting small fluctuations in the posture of a quiet standing subject and the probability that the subject will have an accidental fall within a time period of one year. The data can be understood on the basis of random velocity fluctuations providing kinetic energy in dynamical posture modes. The kinetic energy can activate a transition over the a potential energy barrier which keeps subjects in a metastable standing mode. The probability for a fall then follows an Arrhenius activation law.

cond-mat.soft↗

arXiv2001

Landau-Khalatnikov Circuit model for Ferroelectric Hysteresis

We present the circuit equivalent of the Landau-Khalatnikov dynamical ferroelectric model. The differential equation for hysteretic behavior is subject to numerical computer simulations. The size and shape of the simulated hysteretic loops depends strongly on the frequency and the amplitude of the driving electric field. This dependence makes the experimental extraction of the coercive electric field difficult. The bifurcation of the driven Landau-Khalatnikov model is explained in detail.

cond-mat.stat-mech↗

arXiv2001

Dispersive Techniques for $α_s$, $R_{had}$ and Instability of the Perturbative Vacuum

Recent dispersive techniques developed by us are applied to discuss three problems: 1. A long standing discrepan-cy between the measurements of $R(s)$ for $\sqrt{s} = (5÷7.5)GeV$ by Crystal Ball and MARK I has been analyzed and its consequences analyzed for the number of contributing quarks. 2. Noting that the perturbative $α_s$ has the wrong analyticity, analytic models consistent with asymptotic freedom (AF) and confinement have been constructed and applied to discuss $τ$ decay. 3. It is shown that AF leads to a wrong sign for $\im\big(α(s)\big)$ which signals an instability of the perturbative QCD vacuum.

hep-ph↗

arXiv2001

Physical Kinetics of Ferroelectric Hysteresis

The physical kinetics of single domain ferroelectric materials are studied using Landau-Khalatnikov equation. The hysteretic curves are obtained numerically. The effective coercive electric field theoretically varies with the driving amplitude and frequency. The effects of thermal noise are explored using the Fokker-Planck kinetic equation. The ferroelectric switching times are discussed and Quantum effects are briefly explored.

cond-mat.stat-mech↗