Non-resonant Frequencies Research Articles

MINIMIZATION OF NONRESONANT EFFECTS IN A SCALABLE ISING SPIN QUANTUM COMPUTER

The errors caused by the transitions with large frequency offsets (nonresonant transitions) are calculated analytically for a scalable solid-state quantum computer based on a one-dimensional spin chain with Ising interactions between neighboring spins. Selective excitations of the spins are enabled by a uniform gradient of the external magnetic field. We calculate the probabilities of all unwanted nonresonant transitions associated with the flip of each spin with nonresonant frequency and with flips of two spins: one with resonant and one with nonresonant frequencies. It is shown that these errors oscillate with changing gradient of the external magnetic field. Choosing the optimal values of this gradient allows us to decrease these errors by 50%.

Optimizing non-resonant frequency conversion in periodically poled media

Non-resonant frequency conversion into the blue, green, orange, and red spectral regions is reported. Fundamental light sources were continuous-wave non-planar monolithic single-mode ring Nd : YAG lasers as well as a standing-wave multi-mode Nd : YAG laser. Periodically poled KTiOPO4 was employed as the nonlinear medium, but the considerations could also be applied to other periodically poled materials. A multi-pass scheme resulted in a normalized conversion efficiency as high as 27.2 % W-1 for frequency doubling in the small-signal regime at 1064 nm.

Density-functional theory calculations of optical rotatory dispersion in the nonresonant and resonant frequency regions.

The complex linear response function, which can be employed for calculations of second-order molecular properties in regions of strong absorption, is here extended to encompass the mixed electric-dipole-magnetic-dipole polarizability. The mixed electric-dipole-magnetic-dipole polarizability determines the optical rotation and, when absorption is taken into account, the full anomalous optical rotatory dispersion (ORD) spectra of chiral molecules can be calculated using first-principle quantum-chemical methods. Gauge-origin independence of the results is ensured through the use of London atomic orbitals. To illustrate the importance of taking the absorption process properly into account, we here apply this methodology to the study of the anomalous ORD of hydrogen peroxide, 3R-methylcyclohexanone, 4R-1,1-dimethyl-[3]-(1,2)-ferrocenophan-2-on, and the D(2) isomer of the C(84) fullerene.

Chirality-dependent absorption and third-order polarizability spectra in open single-wall carbon nanotubes

The optimized configurations and electronic structures have been obtained based on the density-functional theory for finite open single-walled carbon nanotubes of (4,4) and (5,5). The calculated results show that the bond lengths, bond angles, and charge distributions at the tube ends are significantly different from those at the tube wall. Then, the electronic absorption spectra of the two tubes are calculated by the time-dependent density-functional theory. The evidences show agreement between the theoretical and available experimental results. A strong and wide absorption band occurs for the case of light polarized parallel to the tube axis; a weak absorption and large transparent range appear as the case of light polarized perpendicular to the tube axis. Finally, the dynamic third-order optical polarizabilities in the three optical processes are obtained in terms of the sum-over-states method combined with the above-mentioned method. It is found that the anisotropy of the polarizabilities is larger for the (4,4) than (5,5) tube, and the tube with a larger axial length and smaller diameter has a larger third-order optical polarizabilities at nonresonant frequencies. The largest third-order polarizability is in the direction of both the polarized light and basic light along with the tube axis, and two photon excitation states make main contributions to the polarizabilities of the (4,4) and (5,5) tubes.

Discrete Fredholm properties and convergence estimates for the electric field integral equation

The Galerkin discretization of the Electric Field Integral Equation is reinvestigated. We prove quasi-optimal convergence estimates at nonresonant frequencies, using orthogonal splittings of the Galerkin space. At resonant frequencies we show that the spurious electric currents radiate only weakly in the exterior domain. This is achieved through the study of some finitely degenerated problems in terms of LBB Inf-Sup estimates and the use of discrete Helmholtz decompositions.

Resonance ionization spectroscopy of fermium ( Z=100)

Laser spectroscopy has been applied for the first time to measure resonant transition frequencies of fermium ( Z=100). A number of 2.7×10 10 atoms was electrodeposited on a Ta filament and covered with a 1 μm Ti layer. Fm atoms were evaporated from the filament at a temperature of approximately 1000 °C into an optical cell filled with a buffer gas and were subsequently photoionized in a two-photon 1+1′ process using a tunable excimer-pumped dye laser and the excimer (XeF) laser itself to produce the resonant (1) and non-resonant (1′) photon frequencies, respectively. The created photoions were identified by mass-selective detection. We observed resonant transitions of Fm at dye-laser energies of 25 099.8(2) and 25 111.8(2) cm −1. A possible classification of these levels is given on the basis of multiconfiguration Dirac–Fock calculations. We also interpreted the recorded time of ion drift through the buffer gas as a novel way to measure the mean ionic charge radius of the heavy elements.

Particle‐in‐cell simulations of Alfvén‐cyclotron wave scattering: Proton velocity distributions

Alfvén‐cyclotron fluctuations propagating parallel or antiparallel to the background magnetic field Bo help shape solar wind ion velocity distributions fi(v). Alfvén waves may be generated at low, nonresonant frequencies and, by propagation through the inhomogeneous plasma, attain ion cyclotron resonances and thereby scatter the fi(v) to anisotropy. Ion anisotropies of sufficient magnitude lead to the growth of ion cyclotron instabilities; the resulting enhanced Alfvén‐cyclotron fluctuations scatter ions so as to reduce the anisotropy. Here particle‐in‐cell simulations were carried out in a magnetized, homogeneous, collisionless plasma of electrons and one ion species to study the evolution of the fi(v) in response to both of these scattering processes. A simulation with a spectrum of right‐traveling Alfvén‐cyclotron fluctuations imposed at t = 0 leads to non‐Maxwellian ion distributions. The computations show that the pitch angle scattering of left‐traveling (v∥ < 0) ions becomes weaker as v∥ becomes less negative but also that this scattering can transport ions across the condition v∥ = 0, where the subscript denotes the direction parallel to Bo.

Acoustic Wave Propagation in the Sun: Implications for Wave Field and Time-Distance Helioseismology

We present results of the numerical simulation of acoustic wave propagation in the Sun's subphotospheric layers. A finite-difference code is used to calculate the pressure perturbation in the frequency domain. We show that the oscillatory seismic signals are closely associated with the solar density and sound speed structures. Owing to the acoustic cutoff frequency, the reduction in the group velocity relative to the background sound speed varies significantly with frequency, especially at low frequencies. This variation causes acoustic wave dispersion, which results in the nonuniform frequency content in the oscillatory signals in the wave packets. An asymptotic arrival generated by the constructive interference of the high-order bounces is observed in the synthetic seismic traces. The synthetic seismic traces presented in this study can provide the basis for wave field tomography, in which phase and amplitude information (including the nonresonant frequencies) is exploited, to enhance the spatial resolution of the reconstructed solar models.

OS09W0223 Cure monitoring of composite laminate by piezoelectric ceramics having different dimensions

The piezoelectric ceramics with different dimensions are embedded into the composite laminates. The impedance of the piezoelectric are measured by a LCR meter in the autoclave processing. The impedance of the piezoelectric ceramics at non-resonant frequencies is adopted as the cure index. The piezoelectric ceramics have strong temperature dependency. The temperature dependency is corrected by using a dummy piezoelectric ceramics. A dielectric sensor is also embedded in the composite laminate as a reference sensor for the degree of cure. The change in corrected impedance at non-resonant frequency shows good correspondence with change in the log ion viscosity which is measured by the dielectric cure monitoring sensor. At the cooling stage, the changes in the impedance of the piezoelectric ceramics depend on the dimension of the piezoelectric. A finite element method is used for analyzing the deformations of the piezoelectric ceramics in the composite laminate at the cooling stage. The changes of the impedance of the piezoelectric ceramics are dominated by the deformation of polarizing direction.

Effect of nonresonant frequencies on the enhancement of quantum beat amplitudes in rovibrational states of Li2: The role of state spacing

Optical phase manipulation of nonresonant frequencies is investigated as a method of achieving optimal population transfer during resonant impulsive stimulated Raman scattering. Wave packets containing quantum beats between an initially prepared rovibrational level in the A(1Σu+) electronic state of Li2 and states populated via a resonance-enhanced rotational Raman process are created using a shaped ultrafast pulse centered near 800 nm. Study of these wave packets allows a quantitative comparison of population transfer as a function of applied phases in the ultrafast pulse. Two cases are explored to determine the ability to enhance population transfer: one with a wide state spacing [A(νA=11, JA=28)-A(11,30) at 50.1 cm−1] and one with a narrow spacing [A(11,8)-A(11,10) at 16.6 cm−1]. In both cases, several different phase masks are applied to the wave packet preparation pulse to enhance the population transferred to the newly formed state of interest. One phase mask involves the application of a −90° phase shift to the nonresonant optical frequencies that lie between the resonant transition frequencies, resulting in an optimal phase relationship between pairs of nonresonant frequencies contributing to the Stokes–Raman excitation. Another extends the phase modification to the nonresonant frequencies lying outside the two resonant transitions to allow constructive enhancement from a larger range of frequencies. Significant population enhancements, up to a factor of ∼12, of the newly formed A(11,30) and A(11,10) states are demonstrated. In addition, the dependence on the state spacing and therefore the extent to which nonresonant frequencies affect the population transferred in the stimulated Raman process are demonstrated.

Relativistic plasma maser interaction in the presence of ion acoustic turbulence

The plasma maser interaction between the high frequency nonresonant ordinary mode and low frequency resonant ion acoustic mode in a relativistic plasma has been studied for the first time. It has been shown that the growth rate of the high frequency wave occurs through the plasma maser interaction between relativistic electrons and the ion acoustic wave turbulence.

Simultaneous control of time-dependent population transfer dynamics and wave-packet quantum interferences inLi2by shaped ultrafast pulses

Ultrafast pulse shapes are used to control simultaneously the optimal population transfer coefficients and rotational wave-packet quantum interferences in the $E{}^{1}{\ensuremath{\Sigma}}_{g}^{+}$ state of ${\mathrm{Li}}_{2}$ $({\ensuremath{\nu}}_{E}=9,$ ${J}_{E}=27$ and 29). By dividing the spectral bandwidth of the ultrafast pulses into multiple ``control domains'' centered on each resonant wavelength, the population transfer coefficients can be manipulated independently of the wave-packet interferences to maximize the ${\mathrm{Li}}_{2}$ photoionization yield at arbitrary short pump-probe time delays. To investigate the population transfer coefficients with and without wave-packet interferences, respectively, the pump polarization is set to be either parallel to or at the magic angle (\ensuremath{\sim}55\ifmmode^\circ\else\textdegree\fi{}) relative to the probe polarization. A comparison is made between phases that are symmetric and antisymmetric about the resonances. The effects of resonant and nonresonant frequencies are separately established and quantified. It is estimated that up to 90% of the possible nonresonant Rabi oscillations can be brought into phase simultaneously for each rovibrational state in the wave packet, while at the same time a constant phase offset added to one of the control domains establishes the phase of the wave-packet interference.

Optimization of geometrical structure and simulation of the spectra of third-order nonlinear optical polarizabilities inC59SiandC58Si2heterofullerenes

We report the optimized geometrical structures using the ab initio method, and the calculated frequency dependence of the third-order nonlinear optical polarizabilities $\ensuremath{\gamma}$ in the different optical processes of the third-harmonic generation, electric-field induced second-harmonic generation, and degenerate four-wave mixing using the INDO/SDCI method coupled with the sum-over-states method for ${\mathrm{C}}_{59}\mathrm{Si}$ and two isomers of ${\mathrm{C}}_{58}{\mathrm{Si}}_{2}$ heterofullerenes. The optimized structures show that the stabilization of the para isomer of ${\mathrm{C}}_{58}{\mathrm{Si}}_{2}$ is larger than that of the dia isomer of ${\mathrm{C}}_{58}{\mathrm{Si}}_{2},$ and the geometrical modifications of ${\mathrm{C}}_{59}\mathrm{Si}$ and ${\mathrm{C}}_{58}{\mathrm{Si}}_{2}$ isomers occur in the vicinity of the Si-doped atom after the replacement of one or two C atoms by Si atoms in the ${\mathrm{C}}_{60}$ fullerene. The calculated hyperpolarizabilities at nonresonant frequency show the varied trends in the order of ${\mathrm{C}}_{59}\mathrm{Si}\ensuremath{\approx}$ dia isomer of ${\mathrm{C}}_{58}{\mathrm{Si}}_{2}<$ para isomer of ${\mathrm{C}}_{58}{\mathrm{Si}}_{2}$ at ground state and the charge transfers of two-photon states make significant contributions to third-order optical polarizabilities for the para isomer of ${\mathrm{C}}_{58}{\mathrm{Si}}_{2}.$ The enhancement of first excited singlet state is about one or two order of magnitude at nonresonant frequency. The susceptibilities of $\ensuremath{\chi}(\ensuremath{-}\ensuremath{\omega};\ensuremath{\omega},\ensuremath{\omega},\ensuremath{-}\ensuremath{\omega})$ of these Si-doped fullerene films are estimated to be about ${10}^{\ensuremath{-}10}$ esu at first excited state and ${10}^{\ensuremath{-}11}$ esu at ground state in nonresonant frequency.

An Iterative Solution for Magnetic Field Integral Equation

This paper tests an iterative solver for magnetic field integral equation (MFIE) developed for scattering problems of electrically large bodies. GMRES (generalized minimum residual or Krylov subspace method) is applied to MFIE written in the normal form. The results for the perfectly conducting (PEC) sphere and other PEC structures demonstrate the solver performance. The surface current distributions and absolute convergence rates for the sphere are controlled by direct comparison with the Mie series calculated for the surface current. Both nonresonant and resonant frequencies of the internal cavity are considered. A low-order boundary element model is implemented, with the surface current being constant across each element. Results are compared to the conjugate gradient method on the normal equation (CGNE) and to the GMRES on the original nonsymmetric MFIE. It is found that GMRES on the normal equation typically possesses higher convergence rates than the GMRES on the original MFIE. GMRES on the normal equation is only slightly superior to CGNE when nonresonant frequencies are considered. However, at the frequencies of internal resonances, GMRES on the normal equation is superior to CGNE.

Burst and spike synchronization of coupled neural oscillators

Neural excitability and the bifurcations involved in transitions from quiescence to oscillations largely determine the neuro-computational properties of neurons. Neurons near Hopf bifurcation fire in a small frequency range, respond preferentially to resonant excitation, and are easily synchronized. In the present paper we study the interaction of coupled elliptic bursters with non-resonant spike frequencies. Bursting behaviour arises from recurrent transitions between a quiescent state and repetitive firing, i.e. the rapid oscillatory behaviour is modulated by a slowly varying dynamical process. Bursting is referred to as elliptic bursting when the rest state loses stability via a Hopf bifurcation and the repetitive firing disappears via another Hopf bifurcation or a double limit cycle bifurcation. By studying the fast subsystem of two coupled bursters we obtain a reduced system of equations, allowing the description of synchronized and non-synchronized oscillations depending on frequency detuning and mutual coupling strength. We show that a certain 'overall' coupling constant must exceed a critical value depending on the detuning and the attraction rates in order that burst and spike synchronization can take place. The reduced system allows an analytical study of the bifurcation structure up to codimension-3 revealing a variety of stationary and periodic bifurcations which will be analysed in detail. Finally, the implications of the bifurcation structure for burst and spike synchronization are discussed.

Burst and spike synchronization of coupled neural oscillators

Neural excitability and the bifurcations involved in transitions from quiescence to oscillations largely determine the neuro-computational properties of neurons. Neurons near Hopf bifurcation fire in a small frequency range, respond preferentially to resonant excitation, and are easily synchronized. In the present paper we study the interaction of coupled elliptic bursters with non-resonant spike frequencies. Bursting behaviour arises from recurrent transitions between a quiescent state and repetitive firing, i.e. the rapid oscillatory behaviour is modulated by a slowly varying dynamical process. Bursting is referred to as elliptic bursting when the rest state loses stability via a Hopf bifurcation and the repetitive firing disappears via another Hopf bifurcation or a double limit cycle bifurcation. By studying the fast subsystem of two coupled bursters we obtain a reduced system of equations, allowing the description of synchronized and non-synchronized oscillations depending on frequency detuning and mutual coupling strength. We show that a certain 'overall' coupling constant must exceed a critical value depending on the detuning and the attraction rates in order that burst and spike synchronization can take place. The reduced system allows an analytical study of the bifurcation structure up to codimension-3 revealing a variety of stationary and periodic bifurcations which will be analysed in detail. Finally, the implications of the bifurcation structure for burst and spike synchronization are discussed.

Second harmonic generation by charge-transfer excitons interacting with phonons

Effects of exciton-phonon interaction on the nonlinear optical response of charge-transfer excitons (CTE) are studied in the framework of an exactly solvable model. It is found that the second order excitonic optical polarizability {beta} is modified due to the CTE-phonon interaction. For a nonresonant frequency range, where {beta} is relatively small, the change is not significant. On the contrary, in the vicinity of resonances (when the light frequency {omega}{approximately}{omega}{sub 0} or {omega}{approximately}{omega}{sub 0}/2, {omega}{sub 0} is the CTE transition frequency), the CTE-phonon interaction may remarkably diminish the value of {beta}. This should be taken into account when considering CTE systems in nonlinear optics.

圧電セラミクスによる複合材料積層板の硬化モニタリング

The piezoelectric ceramics is embedded in the glass fiber reinforced plastics (GFRP) laminate. A dielectric sensor is also embedded in the GFRP laminate as a reference sensor for the degree of cure. The cure monitoring of the FRP by the piezoelectric ceramics in autoclave processing is experimentally demonstrated. The impedances of the piezoelectric ceramics have strong tempera-ture dependence. However, the impedances of the piezoelectric ceramics can be corrected to the temperature by the exponential function. Thus, the impedances of the piezoelectric ceramics at the non-resonance frequency are adopted as cure index of the GFRP laminate. The change of impedance at non-resonance frequency shows good correspondence with change of the log ion viscosity, which is measured by the dielectric cure monitoring sensor.

Vibration and Sound Radiation of Visco-Elastically Damped Plates. Acoustic Power Radiation of Point-Excited Beams.

The effects of structural damping and wavenuwmber ratio on the acoustic power radiated by point-excited damped infinite beams and simply supported finite beams with same cross sections have been studied. The numerical calculations of the acoustic power were carried out using Keltie's equations based on the Heckl's power integral. The acoustic medium is assumed to be air, and the effect of the back reaction of the sound field is neglected in the beam response equation. Non-dimensional acoustic power, sound radiation efficiency, and acoustic power conversion efficiencies are presented as functions of wavenumber ratio and beam loss factors. It is shown that the power conversion efficiency of the infinite beam is inversely proportional to the wavenumber ratio and independent of the loss factor below coincidence, and is approximately proportional in inverse to the loss factor above coincidence. The power conversion efficiency of the finite beam has dull peaks with values roughly inverse-proportional to the loss factor at nonresonant frequencies. The similarity of acoustic power radiation between infinite beams and finite beams has been observed when the length and loss factor of beams is increased.

Actuation Properties of Lead Zirconate Titanate Thick Films Structured on Si Membrane by the Aerosol Deposition Method

The results of the direct deposition of lead zirconate titanate [Pb(Zr0.52, Ti0.48)O3] (PZT) thick film on a Si-based structure are presented. The construction of a bottom electrode is very important for successful deposition. The actuation properties of PZT on the Si membrane were investigated. For a 6.2×6.1 mm2, 65-µm-thick Si membrane driven by a 4.7×4.3 mm2, 13-µm-thick PZT layer, the deflections, which were 1.5 µm upon applying 52 V at nonresonance frequency and 22 µm upon applying 8 V at resonance frequency, were measured.