A. Widom

Investigations of amplitude and phase excitation profiles in femtosecond coherence spectroscopy

We present an effective linear response approach to pump–probe femtosecond coherence spectroscopy in the well-separated pulse limit. The treatment presented here is based on a displaced and squeezed state representation for the nonstationary states induced by an ultrashort pump laser pulse or a chemical reaction. The subsequent response of the system to a delayed probe pulse is modeled using closed form nonstationary linear response functions, valid for a multimode vibronically coupled system at arbitrary temperature. When pump–probe signals are simulated using the linear response functions, with the mean nuclear positions and momenta obtained from a rigorous moment analysis of the pump induced (doorway) state, the signals are found to be in excellent agreement with the conventional third-order response approach. The key advantages offered by the moment analysis-based linear response approach include a clear physical interpretation of the amplitude and phase of oscillatory pump–probe signals, a dramatic i...

Investigations of ultrafast nuclear response induced by resonant and nonresonant laser pulses

We analyze the nonstationary vibrational states prepared by ultrashort laser pulses interacting with a two electronic level molecular system. Fully quantum mechanical expressions are derived for all the moments of the coordinate and momentum operators for the vibrational density matrices associated with the ground and excited electronic states. The analysis presented here provides key information concerning the temperature and carrier frequency dependence of the moments, and relates the moments to equilibrium absorption and dispersion line shapes in a manner analogous to the “transform methods” previously used to describe resonance Raman scattering. Particular attention is focused on the first two moments, for which simple analytical expressions are obtained that are computationally easy to implement. The behavior of the first two moments with respect to various parameters such as the pulse carrier (center) frequency, pulse width, mode frequency, electron-nuclear coupling strength, and temperature is inve...

Ultra low momentum neutron catalyzed nuclear reactions on metallic hydride surfaces

Ultra low momentum neutron catalyzed nuclear reactions in metallic hydride system surfaces are discussed. Weak interaction catalysis initially occurs when neutrons (along with neutrinos) are produced from the protons that capture “heavy” electrons. Surface electron masses are shifted upwards by localized condensed matter electromagnetic fields. Condensed matter quantum electrodynamic processes may also shift the densities of final states, allowing an appreciable production of extremely low momentum neutrons, which are thereby efficiently absorbed by nearby nuclei. No Coulomb barriers exist for the weak interaction neutron production or other resulting catalytic processes.

Converse magnetoelectric experiments on a room-temperature spirally ordered hexaferrite

Experiments have been performed to measure magnetoelectric properties of room temperature spirally ordered Sr3Co2Fe24O41 hexaferrite slabs. The measured properties include the magnetic permeability, the magnetization and the strain all as a function of the electric field E and the magnetic intensity H. The material hexaferrite Sr3Co2Fe24O41 exhibits broken symmetries for both time reversal and parity. The product of the two symmetries remains unbroken. This is the central feature of these magnetoelectric materials. A simple physical model is proposed to explain the magnetoelectric effect in these materials.

Quantum electrodynamic circuits at ultralow temperature

Within present low-temperature technology it is possible to construct macroscopic circuits which exhibit quantum behavior, i.e., subcircuit currents and voltages need to be treated as operators rather than numerical quantities. The general theory of “quantum circuits” is discussed with a view toward the experimental verification of quantum electrodynamics on a macroscopic scale.

Neutron production from the fracture of piezoelectric rocks

A theoretical explanation is provided for the experimental evidence that fracturing piezoelectric rocks produces neutrons. The elastic energy microcrack production ultimately yields the macroscopic fracture. The mechanical energy is converted by the piezoelectric effect into electric field energy. The electric field energy decays via radio frequency (microwave) electric field oscillations.Theradiofrequency electricfields accelerate thecondensed matter electrons which then collide with protons producing neutrons and neutrinos.

Spectral line shapes of damped quantum oscillators: Applications to biomolecules

We present a full quantum mechanical treatment, using the quantum fluctuation–dissipation theorem, which is useful in describing the absorption line shape of a system composed of damped vibrational (harmonic) oscillators that are linearly coupled to an electronic excitation. The closed form expressions obtained from the model predict optical line shapes that are identical to standard treatments at high temperature or in the absence of damping. However, at low temperature, quantum corrections become important and the model predicts a skewed optical line shape that reflects the condition of detailed balance and differs significantly from the ‘‘Brownian oscillator’’ model of Yan and Mukamel [J. Chem. Phys. 89, 5160 (1988)]. We also find that quantum effects become observable in the line shape of the overdamped oscillator only when kBT/ℏω0≲ω0 /γ <1, which effectively depresses the temperature for crossover into the quantum regime. In Appendix D we discuss how the time correlator expressions derived for the li...

Equivalent circuit and simulations for the Landau-Khalatnikov model of 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 depend strongly on the frequency and the amplitude of the driving electric field. In previous experiments, this dependence made extraction of the coercive field rather difficult. An alternative experimental method for the determination of the coercive field is here suggested. We also develop in detail the dynamics of bifurcation of a driven Landau-Khalatnikov ferroelectric.

Quantum electrodynamic charge space energy bands in singly connected superconducting weak links

In a weak-link constriction between two bulk superconductors it is well known that the condensed matter Hamiltonian exhibits periodicity in magnetic flux space. It is shown that a quantum electrodynamic treatment of the voltage across the weak link yields energy bands periodic in the space of Maxwell electric flux displacement charge.

On thermodynamic reliability engineering

Section I contains: Thermodynamics: A fundamental science for physics-of-failure. Although reliability mathematics is well established, having probability theory as its basic tool, the reliability science for physics-of-failure lacks a basic foundation. Thermodynamics is a natural candidate. Many engineers do not realize how closely thermodynamics is tied to reliability, because these subjects are treated separately. This section applies the laws of thermodynamics and reliability theory to illustrate the key aspects that link these sciences into “thermodynamic reliability engineering” which helps to understand the reliability physics-of-failure problems. Section II contains: Aging mechanisms and derivations of key physics-of-failure equations used in accelerated testing and reliability analysis. Irreversible mechanisms that cause aging are discussed (using a thermodynamic framework) along with key physics-of-failure reliability models related to aging. In so doing we derive key physics-of-failure time-compression equations used in reliability stemming from Minor’s hypothesis, the Coffin–Manson power law, Peck’s humidity model, and diffusion methods. Section III contains: Time-dependent parametric aging associated with activated processes. When thermal activation is the rate-controlling process, Arrhenius rate kinetics apply. The parametric time-dependence of an Arrhenius mechanism is addressed and leads to predictable time-dependent aging for certain measurable parameters. Our earlier work developed a thermally activated time-dependent model. This paper describes the shape of the free energy aging path in that model. The results are illustrated for some problems in microelectronics.