Dependence Of Resonance Frequency Research Articles

Photon-assisted tunnelling of zero modes in a Majorana wire

Hybrid nanowires with proximity-induced superconductivity in the topological regime host Majorana zero modes (MZMs) at their ends, and networks of such structures can produce topologically protected qubits. In a double-island geometry where each segment hosts a pair of MZMs, inter-pair coupling mixes the charge parity of the islands and opens an energy gap between the even and odd charge states at the inter-island charge degeneracy. Here, we report on the spectroscopic measurement of such an energy gap in an InAs/Al double-island device by tracking the position of the microwave-induced quasiparticle (qp) transitions using a radio-frequency (rf) charge sensor. In zero magnetic field, photon assisted tunneling (PAT) of Cooper pairs gives rise to resonant lines in the 2e-2e periodic charge stability diagram. In the presence of a magnetic field aligned along the nanowire, resonance lines are observed parallel to the inter-island charge degeneracy of the 1e-1e periodic charge stability diagram, where the 1e periodicity results from a zero-energy sub-gap state that emerges in magnetic field. Resonant lines in the charge stability diagram indicate coherent photon assisted tunneling of single-electron states, changing the parity of the two islands. The dependence of resonant frequency on detuning indicates a sizable (GHz-scale) hybridization of zero modes across the junction separating islands.

Nonlinear power loss in the oscillations of coated and uncoated bubbles: Role of thermal, radiation and encapsulating shell damping at various excitation pressures.

This study presents the fundamental equations governing the pressure dependent disipation mechanisms in the oscillations of coated bubbles. A simple generalized model (GM) for coated bubbles accounting for the effect of compressibility of the liquid is presented. The GM was then coupled with nonlinear ODEs that account for the thermal effects. Starting with mass and momentum conservation equations for a bubbly liquid and using the GM, nonlinear pressure dependent terms were derived for power dissipation due to thermal damping (Td), radiation damping (Rd) and dissipation due to the viscosity of liquid (Ld) and coating (Cd). The pressure dependence of the dissipation mechanisms of the coated bubble have been analyzed. The dissipated energies were solved for uncoated and coated 2-20μm in bubbles over a frequency range of 0.25fr-2.5fr (fr is the bubble resonance) and for various acoustic pressures (1kPa-300kPa). Thermal effects were examined for air and C3F8 gas cores. In the case of air bubbles, as pressure increases, the linear thermal model looses accuracy and accurate modeling requires inclusion of the full thermal model. However, for coated C3F8 bubbles of diameter 1-8μm, which are typically used in medical ultrasound, thermal effects maybe neglected even at higher pressures. For uncoated bubbles, when pressure increases, the contributions of Rd grow faster and become the dominant damping mechanism for pressure dependent resonance frequencies (e.g. fundamental and super harmonic resonances). For coated bubbles, Cd is the strongest damping mechanism. As pressure increases, Rd contributes more to damping compared to Ld and Td. For coated bubbles, the often neglected compressibility of the liquid has a strong effect on the oscillations and should be incorporated in models. We show that the scattering to damping ratio (STDR), a measure of the effectiveness of the bubble as contrast agent, is pressure dependent and can be maximized for specific frequency ranges and pressures.

Dressed Rabi Oscillation in a Crystalline Organic Radical.

Free electron laser-powered pulsed electron paramagnetic resonance experiments performed at 240 GHz/8.56 T on the crystalline organic radical 1,3-bisdiphenylene-2-phenylallyl reveal a tip-angle dependent resonant frequency. Frequency shifts as large as 11MHz (45ppm) are observed during a single Rabi oscillation. We attribute the frequency shifts to a "dressing" of the nutation by spin-spin interactions. A nonlinear semiclassical model which includes a temperature- and sample-geometry-dependent demagnetizing field reproduces experimental results. Because experiments are performed without a cavity, radiation damping, the most common nonlinear interaction in magnetic resonance, is negligible in our experiments.

Passive Wireless Pressure Sensing for Gastric Manometry.

We describe a wireless microsystem for gastrointestinal manometry that couples a microfabricated capacitive transducer to a dual-axis inductor, forming a resonant inductor-capacitor (LC) sensor within an ingestible 3D printed biocompatible capsule measuring ø 12 mm × 24 mm. An inductively coupled external telemetry unit wirelessly monitors the pressure dependent resonant frequency of the LC sensor, eliminating the need for integrated power sources within the ingested capsule. In vitro tests in saline show pressure response of −0.6 kHz/mmHg, interrogation distance up to 6 cm, and resolution up to 0.8 mmHg. In vivo functionality is validated with gastrointestinal pressure monitoring in a canine beagle over a 26-hour period.

Effect of Structural Inhomogeneities on the Spin-Wave and Magnetic Properties of Monocrystalline Spinel Ferrite Films in the Microwave Range

We have studied magnetic parameters of monocrystalline manganese spinel ferrite films differing in composition and structural perfection and assessed the effect of dislocation distribution on the frequency dependence of the ferromagnetic resonance (FMR) linewidth in the microwave range. The results demonstrate that, if an external magnetic field is perpendicular to the film surface, electron paramagnetic resonance (EPR) absorption lines correspond to ferromagnetic and spin wave resonances (SWRs). SWR is due to nanostructural surface inhomogeneities. The EPR spectrum of a tangently magnetized film represents a single dipole exchange oscillation spectrum. Parameters of dipole and exchange modes have been determined.

Finite Element Modeling of the Membrane Module

The design and size of the membrane module package have a significant impact on its characteristics. It is necessary to use the finite element modeling calculation of the frequency response of the membrane module’s membrane due to the complexity of the package design. In this study the method of the thin dielectric membrane modeling by the structural and acoustic analysis in the ANSYS software is proposed. This method allows us to perform the calculation taking into account the influence of the front and back chamber size. The dependences of resonance frequency of the front chamber and back chamber on its geometric sizes are obtained. It is shown that by increasing the back chamber size, the value of the membrane sensitivity approaches its value in the open space. The membrane modules’ frequency response is compared and it shown that the presence of the front and back chambers significantly affects the values of the resonance frequency and sensitivity. The method of setting residual stresses in the membrane using thermal impact is used. A complicatedly deformed state of the membrane, called the buckling effect, is obtained. The dielectric membrane’s sensitivity with allowance for the buckling effect is calculated. The results are analyzed and it is shown that the calculated sensitivity of the membrane taking the buckling effect into account has a good coincidence with the measurement results. The proposed method enables us to calculate the membrane module’s frequency response taking the influence of the package design’s peculiarities into account and also the residual stresses in the membrane. The use of structural-acoustic analysis enables us to achieve more accurate results while calculating the membrane frequency response, which increases the efficiency of designing the acoustic pressure transducers, and ensures achieving the product’s optimal characteristics.

Frequency dependence of the polar motion resonance

SUMMARY The nutation of the Celestial Intermediate Pole can be considered as a retrograde diurnal polar motion. As the common polar motion, it presents a resonance, but with period TPM and quality factor QPM differing from the ones characterizing the Chandler wobble (TCW = 430.2−431.6 d, QCW in the interval (56 255) according to Nastula & Gross): according to the nutation analysis presented in a separate paper, this period is about TPM = 380 d and the quality factor becomes −10. In this study, we aim to revisit the geophysical interpretation of this result. Two complementary factors account for the observed values: the non-equilibrium response of the ocean to the pole tide potential in the diurnal band, and the resonance of the solid Earth tide at the free core nutation period. This leads to a resonance of TPM in the vicinity of the free core nutation period, confirmed by estimates derived from nutation analysis.

Amplitude Dependence of Resonance Frequency and its Consequences for Scanning Probe Microscopy.

With recent advances in scanning probe microscopy (SPM), it is now routine to determine the atomic structure of surfaces and molecules while quantifying the local tip-sample interaction potentials. Such quantitative experiments using noncontact frequency modulation atomic force microscopy is based on the accurate measurement of the resonance frequency shift due to the tip-sample interaction. Here, we experimentally show that the resonance frequency of oscillating probes used for SPM experiments change systematically as a function of oscillation amplitude under typical operating conditions. This change in resonance frequency is not due to tip-sample interactions, but rather due to the cantilever strain or geometric effects and thus the resonance frequency is a function of the oscillation amplitude. Our numerical calculations demonstrate that the amplitude dependence of the resonance frequency is an additional yet overlooked systematic error source that can result in nonnegligible errors in measured interaction potentials and forces. Our experimental results and complementary numerical calculations reveal that the frequency shift due to this amplitude dependence needs to be corrected even for experiments with active oscillation amplitude control to be able to quantify the tip-sample interaction potentials and forces with milli-electron volt and pico-Newton resolutions.

Evaluating the coefficient of thermal expansion of additive manufactured AlSi10Mg using microwave techniques

In this paper we have used laser powder bed fusion (PBF) to manufacture and characterize metal microwave components. Here we focus on a 2.5 GHz microwave cavity resonator, manufactured by PBF from the alloy AlSi10Mg. Of particular interest is its thermal expansion coefficient, especially since many microwave applications for PBF produced components will be in satellite systems where extreme ranges of temperature are experienced. We exploit the inherent resonant frequency dependence on cavity geometry, using a number of TM cavity modes, to determine the thermal expansion coefficient over the temperature range 6–450 K. Our results compare well with literature values and show that the material under test exhibits lower thermal expansion when compared with a bulk aluminium alloy alternative (6063).

Tunable strong circular dichroism in a non-chiral metallic metasurface integrated with graphene.

In this paper, we propose a non-chiral metasurface using an array of V-shaped silver nanostructures surrounded by two graphene sheets to obtain a tunable strong circular dichroism. The position of peaks and dips in the dichroism spectrum depends on the Fermi energy of graphene and can be tuned by changing Fermi energy. For Fermi energies larger than a specific value, stronger tunable circular dichroism is observed. Due to the occurrence of circular dichroism in the near-infrared region, the strong dichroism results from the excitation of surface plasmon in the V-shaped silver nanostructures, not surface plasmon polaritons in the graphene sheets. In addition, the observed tunability is attributed to the dependence of plasmon resonance frequency of silver nanostructures on the surrounding graphene sheets.

The equivalent circuit imitating wave scattering by arrays of split-ring resonators

The scattering of waves by a periodic chain of series resonant LC circuits in a two-dimensional lattice of lumped elements is considered, that imitates the scattering of electromagnetic waves by a periodic lattice of split-ring resonators. Using the translation symmetry of this chain we transformed the scattering problem into the problem of wave propagation along the strip with a single LC circuit. This problem was solved analytically presenting the transmittance as a sum of partial transmittances, corresponding to the frequency mini-bands of the strip. It is shown that the transmittance as a function of the incident wave frequency demonstrates two types of resonances with different resonant frequency dependence on the distance between neighbouring LC circuits.

Nontrivial temperature dependence of ferromagnetic resonance frequency for spin reorientation transitions

We find unusual temperature dependence of the ferromagnetic resonance (FMR) frequency $f_{\rm R}$ for the spin-reorientation (SR) transition, in which the easy axis changes depending on temperature, observed in the Nd permanent magnet, Nd$_2$Fe$_{14}$B: $f_{\rm R} \sim 0$ below the SR transition temperature ($T_{\rm R}$), drastic increase of $f_{\rm R}$ around $T_{\rm R}$, and decrease from a peak at higher temperatures. It is nontrivial that the SR transition causes the unusual behavior of the FMR frequency in a wide temperature region. We show the mechanism of the temperature dependence by theoretical and computational analyses. We derive a general relation between $f_{\rm R}$ and magnetizations to help the understanding of the mechanism, and clarify that the fluctuation of the transverse magnetization is a key ingredient for the resonance in all temperature regions.

Dimensional dependence of the radiation damage in microelectromechanical system resonators

The effect of 10 keV x-ray and 255 nm UV radiation on MEMS resonators of different sizes were tested. The change in resonance frequency of the resonator during and after radiation was tracked, and a dimensional dependent resonance frequency reduction was observed for both x-ray and UV irradiation. The dimensional dependence of the resonance frequency shift indicates that surface effects are an important factor in both types of radiation damage. We propose two theoretical models that successfully explain the dimensional dependencies of x-ray and UV radiation damage. The x-ray model is based on hydrogen diffusion in silicon and the UV model is based on radiation induced charging of the native oxide. The models show that larger surface-to-volume ratio devices are more susceptible to radiation and need to be considered when scaling MEMS devices.

Guided electromagnetic waves for periodic arrays of thin metallic wires near an interface between two dielectric media.

Guided localized electromagnetic waves propagating along one-dimensional (1D) arrays of thin metallic parallel wires, finite and infinite, are studied. The arrays are embedded into the upper dielectric half-space close to the interface separating it from the lower dielectric medium with different permittivity and the same permeability. Firstly, a dependence of resonance frequencies of excited wave modes for finite array with respect to the array height above the interface is studied. The array is excited by a normally incident plane wave. It is important that the order of the resonance modes changes if the distance between the array and the interface becomes small. An analysis, based on the Pocklington system of integral equations to evaluate resonance frequencies and compute the fields of excited modes above the array, was applied. This approach is based on the longwave approximation of thin wires. Secondly, the waves propagating along infinite 1D array of thin metallic wires that is close to the interface are studied. Dispersion curves are presented for the lowest case of half-wave resonance for different heights of the array over the interface. When the array approaches very close to the interface an anomalous dispersion is observed. The results of the numerical analysis were tested against computations obtained by means of other independent CST Studio Suite simulations.

Coaxial measurements of microwave permeability of thin supermalloy films under magnetic bias

Abstract We present investigation of microwave permeability of thin supermalloy films deposited on a flexible substrate. The permeability measurements are performed by transmission-reflection technique in a coaxial line under external magnetic bias in the frequency range of 100 MHz–20 GHz. It is shown that demagnetization does not affect the measurements when bias is above 150 Oe. Magnetic characteristics of the films are determined by two approaches: (i) fitting of the resonant frequency dependence on magnetic bias by Kittel's equation and (ii) calculation of the parameters from the Landau–Lifshitz–Gilbert dispersion law. Both approaches give close results for values of magnetoelastic field, anisotropy field, saturation magnetization, and damping factor.

The Dependence of Resonance Frequency to Landing Angle in Reciprocal Scattering Phenomena of the Waves From an Elliptical Plasma Dielectric Antenna

Scattering of an electromagnetic plane wave in transverse electric mode which is obliquely incident to an elliptical plasma antenna with a dielectric rod is comprehensively investigated. The field solutions of the incident, transmitted, and the scattered waves will be derived in terms of Mathieu and modified Mathieu functions. Using asymptotic expansions of Mathieu functions, the scattering cross section per unit length is obtained. It will be shown that in such an elliptical plasma antenna, the backscattering cross section depends on the incident angle and the bistatic scattering cross section varies with scattering angle significantly. Such effects are not seen in antennas with circular cross section due to the circular symmetry in them. The validation of the presented formulations and numerical computation will be examined with the circular case that is an asymptotic well-known case. The graphs of backscattering cross section, scattering pattern, and their corresponding to the polarized charge densities are presented. The dependence of the backscattering cross section and the scattering pattern upon the density and geometrical dimension of the plasma and dielectric are investigated. In addition, it will be shown that the resonance frequencies, under which the plasma antenna response will be maximum, essentially depend on the incident angle of the incident wave.

Small Airway Disease in Pulmonary Hypertension-Additional Diagnostic Value of Multiple Breath Washout and Impulse Oscillometry.

Airways obstruction is frequent in patients with pulmonary hypertension (PH). Small airway disease (SAD) was identified as a major contributor to resistance and symptoms. However, it is easily missed using current diagnostic approaches. We aimed to evaluate more elaborate diagnostic tests such as impulse oscillometry (IOS) and SF6-multiple-breath-washout (MBW) for the assessment of SAD in PH. Twenty-five PH patients undergoing body-plethysmography, IOS and MBW testing were prospectively included and equally matched to pulmonary healthy and non-healthy controls. Lung clearance index (LCI) and acinar ventilation heterogeneity (Sacin) differed significantly between PH, healthy and non-healthy controls. Likewise, differences were found for all IOS parameters between PH and healthy, but not non-healthy controls. Transfer factor corrected for ventilated alveolar volume (TLCO/VA), frequency dependency of resistance (D5-20), resonance frequency (Fres) and Sacin allowed complete differentiation between PH and healthy controls (AUC (area under the curve) = 1.0). Likewise, PH patients were separated from non-healthy controls (AUC 0.762) by D5-20, LCI and conductive ventilation heterogeneity (Scond). Maximal expiratory flow (MEF) values were not associated with additional diagnostic values. MBW and IOS are feasible in PH patients both providing additional information. This can be used to discriminate PH from healthy and non-healthy controls. Therefore, further research targeting SAD in PH and evaluation of therapeutic implications is justified.

Dielectric relaxation studies of Ce0.9-xYxCa0.1O2-δ solid electrolytes

The solid electrolytes of Ce0.9-xYxCa0.1O2-δ with x = 0 and 0.05 were prepared by mechanical milling technique and investigated its dielectric properties. The frequency dependent ac conductivity of this oxide-ion conductor showed an unusual behavior compared to that of the cation conductors. As temperature increases the oxygen vacancy concentration increases due to the dissociation of oxygen vacancies from the defect pairs. The co-doped sample exhibit slightly higher conductivity compared to the singly doped sample. Dielectric relaxation analysis exhibited two relaxation peaks as a result of the bulk and grain boundary ionic migration process. Temperature dependent resonance frequencies and tan δ maxima of the relaxation peaks are used to measure the migration energy EM supporting the O2− migration and dissociation energy ED for the creation of free oxygen vacancy from the defect associates. A single relaxation peak observed in the modulus analysis corresponds to the reorientation relaxation of the defect associates.

Electrical Tunability of Terahertz Amplification in a Periodic Plasmon Graphene Structure with Charge-Carrier Injection

The dependence of the plasmon terahertz resonant frequency in the generation mode on the quasi-Fermi energy in the active (ungated) region of graphene with an inverse charge carrier population and on the Fermi energy in the gated p- and n-type regions in a periodic p–i–n structure based on graphene with injection pumping is theoretically investigated. It is shown that electrically frequency-tunable nanoscale plasmon graphene amplifiers and generators operating in a broad terahertz frequency range at room temperature can be designed.

Monitoring the Carbonation-Induced Microcracking in Alkali-Activated Slag (AAS) by Nonlinear Resonant Acoustic Spectroscopy (NRAS)

Abstract This article presents the potential of nonlinear resonant acoustic spectroscopy (NRAS) for noninvasive monitoring of the carbonation progress in alkali-activated slag (AAS) mortars. In the search for sustainable concrete, AAS has emerged as a potential substitute for ordinary portland cement binder. However, carbonation is reported to be an important durability concern for AAS due to the absence of portlandite. In this study, the correspondence between the physical properties and microstructural evolution of sodium silicate-activated slag (SS-AS) and sodium hydroxide-activated slag (SH-AS) mortars were studied over the full course of accelerated carbonation. The measured properties include the following: compressive strength, carbonation depth, porosity, pore size distribution, and phase assemblage. In addition, NRAS was used to track the changes in materials stiffness (linear resonance frequency) and hysteretic nonlinearity (amplitude dependency of resonance frequency). Scanning electron microscopy (SEM) images and porosimetry results showed the formation of microcracks and increased micrometer porosity in a carbonated AAS binder caused by calcium aluminum silicate hydrate decalcification; the cracking was more severe in the SS-AS than in the SH-AS. The NRAS results revealed a close correspondence between the observed microscopic changes in the samples and measured macroscopic test parameters, indicating the potential of acoustic techniques for monitoring the advancement of carbonation fronts in AAS mortars.