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Various approaches have been used in the literature for eliminating nonresonant levels in atomic systems and deriving effective Hamiltonians. Important among these are elimination techniques at the level of probability amplitudes, operator techniques to project the dynamics on to the subspace of resonant levels, Green’s function techniques, the James’ effective Hamiltonian approach, etc. None of the previous approaches is suitable for deriving effective Hamiltonians in intracavity situations. However, the James’ approach does work in the case of only two-photon transitions in a cavity. A generalization of the James’ approach works in the case of three-photon transitions in a cavity, but only under Raman-like resonant conditions. Another important approach for adiabatic elimination is based on an adaptation of the Markov approximation well-known in the theory of system–bath interactions. However, this approach has not been shown to work in intracavity situations. In this paper, we present a method of adiabatic elimination for atoms inside cavities in the presence of multiphoton transitions. We work in the Heisenberg picture, and our approach has the advantage that it allows one to derive effective Hamiltonians even when Raman-like resonance conditions do not hold. [ABSTRACT FROM AUTHOR]

The results of the numerical-analytical modeling of the photoconductivity of crystalline silicon with the inclusion of amorphous silicon are presented. These ones can be used in studying the principles of a new class of photovoltaic converters based on modified semiconductor materials. The initial data for such a model should be experimentally obtained layer parameters. During the calculations, it was assumed that the change in photoconductivity is caused by a change in the degree of disorder of amorphous inclusions. It was assumed that the semiconductor structure is dominated by cylindrical inclusions and the degree of sample disorder γ varies in the range from 0.040 to 0.065. That is, approximately 5 % of amorphous inclusions in the volume of the crystalline structure. The paper presents the results of calculations of changes in photoconductivity depending on the degree of disorder of the semiconductor structure. The results are in good agreement with obtained experimental data on amorphous-crystalline structures formed as a result of irradiation by γ-quanta. The photoconductivity of semiconductor samples irradiated with gamma rays was studied by microwave photomodulation methods using a resonator measuring transducer. [ABSTRACT FROM AUTHOR]

A system consisting of a magnetic material and a piezoelectric material placed within a microwave cavity is considered. The strong and long-range coupling between the piezoelectric material and the magnetic material mediated by the microwave cavity has been studied. We have shown that the realization of the strong coupling regime is not only possible between each of these materials with the microwave cavity, but also between the magnetic material and the piezoelectric material.

Moisture content is critical to concrete fabrication. Currently, concrete fabrication often involves experienced workers who can gauge whether the water volume is sufficient. This active human involvement requires appearance or thickness checks, which is not suitable for mass production. This method cannot also tell the actual moisture content. Moreover, different workers may give different assessments for the same concrete, which may further lead to different strengths of concrete. Thus, we propose and design a microwave-cavity-based online moisture sensing system to monitor concrete fabrication. Our system utilizes a microwave resonator as a front-end sensor to monitor moisture. This resonator is sensitive to the dielectric coefficient of a particular object. This dielectric coefficient of concrete notably changes when the water yield varies and hence can be readily detected. With this sensitive resonator, we built an online moisture-sensing system. Our prototype achieves moisture sensing with an error of as low as 0.5% and can check moisture content twice a second. [ABSTRACT FROM AUTHOR]

Hybrid quantum systems have attracted much attention due to the fact that they combine the advantages of different physical subsystems. Cavity QED (cavity quantum electrodynamics) with magnons is a hybrid quantum systems that combines a YIG (Yttrium Iron Garnet) sphere and a 3D (three-dimensional) rectangular microwave cavity. Based on this hybrid photon-magnon system, we obtain an approximate analytic solution by the RWA (rotating wave approximation) with an ingenious transformation. After skillfully diagonalizing the Hamiltonian, we show that the Kerr-nonlinearity interactions could yield a negativity value of the Wigner function, periodic quadrature squeezing effects, antibunching property, and field nonclassicality in the magnon. Our work may stimulate the study of nonclassicality of photon-magnon coupling systems and its potential applications in quantum information processing. [ABSTRACT FROM AUTHOR]

Cavity magnonics deals with the interaction of magnons — elementary excitations in magnetic materials — and confined electromagnetic fields. We introduce the basic physics and review the experimental and theoretical progress of this young field that is gearing up for integration in future quantum technologies. Much of its appeal is derived from the strong magnon–photon coupling and the easily-reached nonlinear regime in microwave cavities. The interaction of magnons with light as detected by Brillouin light scattering is enhanced in magnetic optical resonators, which can be employed to cool and heat magnons. The microwave cavity photon-mediated coupling of a magnon mode to a superconducting qubit enables measurements in the single magnon limit. [ABSTRACT FROM AUTHOR]

Abstract Herein, the design and characterization of Ag/SeO2/C avalanche type resonant tunneling devices are reported. Thin pellets of SeO2 nano-powders pressed under hydraulic pressure of 1.0 MPa which is used as the active material are characterized. They showed tetragonal structure refereeing to space group of P 4 2 m b c and lattice parameters of a = b = 7.866 Å and c =5.336 Å. The current-voltage characteristic curves have shown that SeO2 can perform as active media to produce resonant tunneling diodes when forward biased and as avalanche type diode when reverse biased. The peak to valley current ratios of these diodes reached 18.3. In addition, the impedance spectroscopy measurements have shown that the device works in the low impedance mode when operated in the microwave range of frequency near 1.50 GHz. Negative conductance effect is observed in that frequency domain. The features of the Ag/SeO2/C nominate them for use as signal amplifiers and microwave oscillators.

Precision microwave spectroscopy of the ground-state hyperfine structure in muonium provides a stringent test of the Standard Model in particle physics. The MuSEUM collaboration is preparing for such a measurement, aiming for precision down to ≈ 1 ppb, utilizing the world's most intense pulsed muon beam at J-PARC. The measurement of the Zeeman-split structure with an external magnetic field of 1.7 T also precisely determines the muon's magnetic moment (≈ 10 ppb). In the future, improved precision of the magnetic moment can be potentially obtained by measurements with different magnetic field strengths, however, it entails upgrading current cylindrical microwave cavities to rectangular ones. As the first step for the upgrade, we have developed a dual-mode rectangular cavity for the measurement with 2.9 T field. The electromagnetic design and production have been established, and frequency sweeping with two desired modes has been successfully demonstrated. Moreover, the overall performance of the measurement at 2.9 T field was evaluated with Monte Carlo simulations. These studies pave the way for a further extension of the MuSEUM experiment at various strengths of the magnetic fields. [ABSTRACT FROM AUTHOR]

Herein, powders of SeO2 are subjected to hydraulic pressure in the range of 1.0–12 MPa and heating cycles in the range of 290–383 K. The pressure and temperature effects on the crystalline nature, plane orientations, structural parameters, surface morphology, composition, electrical resistivity, capacitance spectra and conductance spectra are explored. It is observed that hydraulic pressure value of 6.0 MPa is a critical value at which the tetragonal SeO2 grains prefer (020) plane orientation over (011) planes. The (020) plane orientations resulted in remarkable changes in the lattice parameters, structural parameters, electrical resistivity, capacitance and conductance spectra. In addition, the heating and cooling cycles of the samples pressed at 10 MPa have shown that the transition of the planes is permanent. The heated and cooled pellets displayed resonance–antiresonance in the capacitance spectra near 0.43 GHz. The resonance–antiresonance phenomena are accompanied with negative conductance effect near 0.43 GHz. The enhancements in the properties of SeO2 powders that are achieved via pressure and temperature effects make them appropriate for electronic circuit technological applications. [ABSTRACT FROM AUTHOR]

Herein, the structural, morphological, optical and electrical properties of CdO stacked layers comprising Si slabs of thickness of 100 nm are investigated. The performance of the stacked layers, which are prepared by the thermal evaporation technique under vacuum pressure of 10-5 mbar, is remarkably enhanced via insertion of Si thin slabs. The presence of Si slabs between the layers of CdO improves the crystallinity and surface morphology, increases the light absorbability in the ultraviolet and visible ranges of light and also increases the dielectric constant, the quality factor, and optical conductivity values. The optical conductivity parameters, which are analyzed in accordance with Drude-Lorentz approach, have shown that the insertion of the Si layers rises the values of the drift mobility of holes in CdO and lowers the free holes concentration. The energy band gap of CdO films is narrowed from 2.20 to 1.27 eV upon insertion of Si slabs. The applicability of the plasmonic CdO/Si/CdO devices as low pass filers in the frequency domain of 0.01-1.80 GHz is verified through impedance spectroscopy measurements.

Miniaturized microwave cavities constructed by the parallel-plate waveguide (PPW) becomes one of the main propagation pathways of the radio-frequency interference (RFI) in 3-D integrated circuits. It is still challenging to suppress RFI in the practical cavities, where the space is extremely constrained. In this work, the working mechanism and design method of the noise suppression sheet (NSS) is quantitatively studied, serving as an efficient approach to suppress RFI within an electrically small size in these microwave cavities. The analysis is based on the dispersion relationship derivation of the NSS-loaded PPW structure. Both the derived formulas and the numerical study reveal that the imaginary part of the permeability, that is, $\mu _{i}$ , of the NSS plays a key role in increasing the reflection and attenuation loss, and thus obtaining a high RFI suppression level. Further study indicates even when the NSS’s profile is lower than 10% of the cavity’s height and the length is lower than $0.1\lambda _{0}$ , its suppression level up to 10 dB can be well accomplished, which is deemed difficult to achieve by using conventional methods. Moreover, this method is, respectively, applied in three practical engineering scenarios for the RFI suppression, that is, heatsink package above a chip, power distributed network (PDN), and flexible circuit. Good agreement is observed between the measurement results and the simulated ones, which confirmed the efficacy of our quantitatively developed NSS. The proposed method is promising for broad industrial applications, such as tiny chip packages, multi-channel systems, and flexible electronics. [ABSTRACT FROM AUTHOR]

A simple and feasible scheme for the generation and manipulation of phonon lasering is proposed and investigated based on a generic three-mode cavity magnomechanical system, in which a magnon mode couples simultaneously with a microwave cavity mode and a phonon mode. In sharp contrast to all previous phonon lasering schemes with only a single drive, the input pump field for the system in the proposed scheme is split into two microwave driving fields to drive the microwave cavity mode and the magnon mode, respectively. The impact of changing relative phase and relative amplitude ratio of the two microwave drives on mechanical gain, stimulated emitted phonon number, threshold power, and phonon emission line shape are theoretically and numerically investigated. The results indicate that the phonon laser action can be effectively controlled simply by adjusting the relative phase and relative amplitude ratio, so additional and tunable degrees of freedom are introduced to control the phonon laser. Considering the experimental feasibility of the generic cavity magnomechanical system and the two-drive approach, the present scheme provides a potentially practical route for the development of tunable phonon lasering devices with low-threshold, high-gain, and narrow-linewidth properties based on the platform of cavity magnomechanics.

We present a comprehensive exploration of loop-gap resonators for electron spin resonance (ESR) studies, enabling investigations into the hybridization of solid-state magnetic materials with microwave polariton modes. The experimental setup, implemented in a Physical Property Measurement System by Quantum Design, allows for measurements of ESR spectra at temperatures as low as 2 Kelvin. The versatility of continuous wave ESR spectroscopy is demonstrated through experiments on CuSO4⋅5H 2 O and MgCr 2 O 4 , showcasing the g-tensor and magnetic susceptibilities of these materials. The study delves into the challenges of fitting spectra under strong hybridization conditions and underscores the significance of proper calibration and stabilization. The detailed guide provided serves as a valuable resource for laboratories interested in exploring hybrid quantum systems through microwave resonators., (Creative Commons Attribution license.)

Hybrid quantum systems have attracted much attention due to the fact that they combine the advantages of different physical subsystems. Cavity QED (cavity quantum electrodynamics) with magnons is a hybrid quantum systems that combines a YIG (Yttrium Iron Garnet) sphere and a 3D (three-dimensional) rectangular microwave cavity. Based on this hybrid photon-magnon system, we obtain an approximate analytic solution by the RWA (rotating wave approximation) with an ingenious transformation. After skillfully diagonalizing the Hamiltonian, we show that the Kerr-nonlinearity interactions could yield a negativity value of the Wigner function, periodic quadrature squeezing effects, antibunching property, and field nonclassicality in the magnon. Our work may stimulate the study of nonclassicality of photon-magnon coupling systems and its potential applications in quantum information processing.

Abstract Herein, metal-oxide-semiconductor fields effect transistors (MOSFET) are fabricated and characterized. p − type germanium dioxide coated onto Au/ n-CdSe substrates and top contacted with carbon point contacts is used to form the MOSFET devices. The structural investigations which were carried out with the help of X-ray diffraction technique revealed large lattice mismatched polycrystalline layers of CdSe and GeO2. The design of the energy band diagram has shown the formation of two Schottky arms (Au/ n − CdSe, C/GeO2) at the interfaces of the n − CdSe/ p − GeO2 layers. The capacitance-voltage characteristics which are recorded in the frequency domain of 1.0-50.0 MHz revealed the ability of formation of NMOS and PMOS layers. The signal frequency controlled built in potential is tunable in the range of 2.34 and 5.18 eV. In addition, the conductance and capacitance spectral analyses in the frequency domain of 10-1800 MHz revealed the domination of current conduction by tunneling and correlated barriers hoping below and above 760 MHz, respectively. In addition to its features as MOSFET devices, the Au/CdSe/GeO2/C hybrid devices are found to be appropriate for use as microwave cavities.

We report on the magnetic levitation of a millimeter-sized neodymium permanent magnet within the interior of a superconducting radio frequency (SRF) cavity. To the best of our knowledge, this is the first experimental work on levitating a magnet within an SRF cavity. The cavity is a coaxial quarter-wave microwave resonator made from 6061 aluminum, having a resonance frequency of 10 GHz and a loaded Q of 1400. The cylindrical magnet (N50) has a height of 1 mm, a diameter of 0.75 mm, a mass of 4 mg, and a remanence of 1.44 T. This produces a peak magnetic field 140 times greater than the critical field of aluminum. The magnet is placed either on the top of the coaxial portion of the cavity or on the cavity floor before cooling it below the superconducting transition temperature of aluminum. The coaxial mode's resonance frequency shifts as a function of the levitation height of the magnet and gives an idea of the magnet's position and mechanical motion. We observe a transition at a temperature of 650 mK where the Meissner effect levitates the magnet as the material beneath the magnet becomes superconducting. The magnet is levitated to a height of 2.5 mm above the surface of the cavity stub, which is a sufficient separation for the field strength of the magnet at the surface of the stub to be less than the critical field strength of the superconducting aluminum. We measure a 120 MHz upshift in the cavity resonance as the magnet is levitated from the top of the stub and 15 MHz downshift as it levitates from the floor of the cavity. Our measurements are consistent over several heating and cooling cycles. Our work provides a path towards a novel optomechanical system. [ABSTRACT FROM AUTHOR]

Here, we research a novel cavity magnomechanical system, where the magnon mode with Kerr nonlinearity driven by a microwave field couples to a phonon mode with a magneostrictive nonlinear interaction (radiation pressure-like). Based on these nonlinear properties, we numerically demonstrate magnon chaos in the PT-symmetry and PT-symmetry broken regimes in the system. In the PT-symmetry broken phase, the magnon-chaos driving threshold is lowered to a rather low levels benefited from the enhancement of the system nonlinearities. Moreover, by expenediently manipulating the phase transition between PT-symmetry and PT-symmetry broken regimes, we can switch the system between into and out of chaotic regimes. Our work may broaden the cavity magnomehcnaics and provide a promising application for magnetic chaos-related security communications.

In this work, amorphous InSe thin films coated with 30–160-nm-thick SiO2 are used as an active material to fabricate multifunctional devices. The n-InSe/p-SiO2 layers that are deposited onto ytterbium substrates are optically and electrically characterized. It was observed that the coating of SiO2 nanosheets onto the surface of InSe enhances the light absorbability in the near-infrared range without remarkable altering of the bandgap. Significant increase in the steady-state photocurrent values accompanied by faster photocurrent responses resulted from the coating of SiO2 nanosheets. Electrically, while the Yb/InSe/Au channels display tunneling Schottky barrier characteristics, the Yb/InSe/SiO2/Au channels show pn junction features. Both channels displayed metal–oxide–semiconductors (MOS) capacitance–voltage characteristics. In addition, the analyses of the current–voltage characteristics have shown that the currents in the Yb/InSe/Au and Yb/InSe/SiO2(30 nm)/Au channel are dominated by electric field-assisted thermionic emission (tunneling) of charge carriers through barriers of widths of 18/14 and 30/16 nm under reverse-/forward-biasing conditions, respectively. Further increase in the oxide layer thickness lowered the barrier height of the devices. On the other hand, when an ac signal of low amplitude is imposed through the device channels, the conductance, capacitance, and reflection coefficient spectra displayed bandstop filter characteristics near 1.6 GHz. The microwave cutoff frequency spectra show a remarkable increase in the cutoff frequency values as a result of the coating of InSe with SiO2 nanosheets. The features of the device assure its applicability as rectifying diodes, fast photosensors, MOS capacitors, and microwave bandstop filters. [ABSTRACT FROM AUTHOR]

Herein, we report the design and experimental characterization of a broken gap heterojunction devices fabricated by vacuum evaporation of Yb/InSe/Sb2Te3/Au stacked layers. The structural characterizations of the stacked layers revealed an amorphous/polycrystalline heterojunction type. The measurements of capacitance-voltage characteristics in the frequency domain of 1.0-9.0 MHz displayed tunable metal-oxidesemiconductor (MOS) characteristics. The frequency dependent built-in voltage, depletion width, and free carrier density is also investigated. In addition, the analyses of currentvoltage characteristics have shown that the device displays highly stable current rectification ratios of ~103 above 0.20 V. Moreover, the ac signal analyses in the frequency domain of 10-1800 MHz have shown the possible tunability of the conductance and capacitance over a wide range of frequency. Furthermore, the microwave cutoff frequency spectra indicated increasing cutoff frequency limits with increasing incident signal frequency. The microwave cutoff frequency reached 7.1 GHz for a propagating signal of frequency of 1800 MHz. [ABSTRACT FROM AUTHOR]

An experimental method and apparatus for investigating the interaction mechanism between microwave field and semiconductor material are presented in this paper. The investigation is based on a dual-mode compressed rectangular cavity, which includes the TE102 and TE103 modes. The TE102 mode is used for providing the stimulus signal, which supplies the microwave field during the experiment, and the TE103 mode is for testing. The two modes are individually coupled to the cavity, and two band-stop filters are introduced to isolate the signals coming from both the modes. A directional coupler is utilized to monitor the power level of the stimulus signal. Experimental results demonstrate that microwave field may affect the inherent characteristics of indium phosphate, a typical kind of semiconductor materials, which eventually leads to the nonlinear behavior of the dielectric property. After the microwave field strength exceeds a critical value, the nonlinear behavior of the microwave materials becomes more and more drastic along with further increasing field strength, and according to the particular experiment setup, we conclude that the nonlinear behavior is not caused by microwave thermal effect, but some inherent characteristics of the material itself. In addition, the experimental method and apparatus can also be employed to predict the consequences of the non-thermal action of microwave effect of other high-power microwave material under microwave field.

In this article, Au/As2Se3/Ag/As2Se3/Yb Schottky barriers are formed and characterized. The devices prepared by the thermal evaporation technique under vacuum pressure of 10−5 mbar are observed to exhibit metal-induced crystallization process when coated onto Au substrates. Electrically, the arsenic selenide-based Schottky devices exhibited typical metal-oxide-semiconductor (MOS) characteristics with a built-in potential of 0.17 eV. The device shows resonance–antiresonance switching, negative capacitance (NC) effect, and high to low conductance switching features in the frequency domain of 10–1800 MHz. In addition, measurement of the impedance, amplitude of reflection coefficient, return loss (Lr), and voltage standing wave ratio (VSWR) spectra in the same domain have shown that the Au/As2Se3/Ag/As2Se3/Yb Schottky barriers display band stop features at 1180 MHz. The Lr and VSWR values at this critical frequency are 29.1 dB and 1.1, respectively. The electrical characterizations of the Au/As2Se3/Ag/As2Se3/Yb MOS devices have confirmed their suitability for use as parasitic capacitance cancellers, noise reducers, and as switching clock with selective switching time scales of switching delay time less than 0.40 ns. [ABSTRACT FROM AUTHOR]

In this work, hybrid devices composed of n − As 2 Se 3 / p − MoO 3 encapsulated between two Schottky shoulders (Au/ n -As 2 Se 3 , Ag/MoO 3) are prepared and characterized. While the structural analyses proofed the preferred growth of monoclinic MoO 3 onto amorphous layers of As 2 Se 3 , the spectroscopic ellipsometry analysis revealed the high frequency dielectric constants, the effective mass and the negative pseudodielectric constant values. Electrically, the hybrid device displayed both tunneling and standard diode characteristics. As passive mode devices, the capacitance-voltage characteristics displayed the accumulation-depletion -inversion modes in the device. Furthermore, the conductivity spectral analysis has shown that the current conduction is dominated by the quantum mechanical tunneling and correlated barriers hoping mechanisms. The amplitude of the reflection coefficient and the return loss spectral analyses indicated that the hybrid devices are band stop filters in addition to it is usability as nonlinear optical interfaces, CMOS device and tunneling diodes. Image 1 • Au/n-As 2 Se 3 /p-MoO 3 /Ag hybrid devices are fabricated and characterized. • The structure and morphology of the device is investigated. • The pseudo-dielectric dispersion is studied by spectral ellipsometry technique. • The current and capacitance-voltage characteristics are analyzed. • The impedance spectroscopy in the 10–1800 MHz frequency domain is reported. [ABSTRACT FROM AUTHOR]

In this article, the physical design, energy band diagram, temperature dependent electrical resistivity and the impedance spectroscopy measurements of the Au/Bi2O3/ZnS/Ag isotype heterojunction devices are reported. The devices are prepared by the thermal evaporation technique under vacuum pressure of 10-5 mbar. Structural, compositional and morphological studies has shown the presence of an expansion in the lattice of Bi2O3 associated with increased strain and dislocation density and decreased grain size as a result of ZnS interfacing. The design of the band diagram indicated that the formed heterojunction exhibit large valence and conduction band offsets that forces charge accumulation at the interface. The Au/Bi2O3/ZnS/Ag device displays negative capacitance (NC) effect in the frequency domain of 0.01-1.50 GHz. The NC effect is interrupted by a resonance-antiresonance phenomenon in the frequency domain of 0.90-1.07 GHz. In addition to the NC effects, the device under study exhibited reflection coefficient and return loss spectra that nominate it for use as microwave cavities or as low pass band filters. [ABSTRACT FROM AUTHOR]

Generalized eigenvalue problems are standard problems in computational sciences. They may arise in electromagnetic fields from the discretization of the Helmholtz equation by for example the finite element method (FEM). Geometrical perturbations of the structure under concern lead to a new generalized eigenvalue problems with different system matrices. Geometrical perturbations may arise by manufacturing tolerances, harsh operating conditions or during shape optimization. Directly solving the eigenvalue problem for each perturbation is computationally costly. The perturbed eigenpairs can be approximated using eigenpair derivatives. Two common approaches for the calculation of eigenpair derivatives, namely modal superposition method and direct algebraic methods, are discussed in this paper. Based on the direct algebraic methods an iterative algorithm is developed for efficiently calculating the eigenvalues and eigenvectors of the perturbed geometry from the eigenvalues and eigenvectors of the unperturbed geometry. [ABSTRACT FROM AUTHOR]

In this paper we describe a microwave sensor for microfluidic sensing using a split ring resonator (SRR) with the sample parallel to the electric field to improve its sensitivity. It is designed to operate at 2.5 GHz with a 3 mm active gap region, over a volume of approximately 10 m m 3 . The SRR has been tested with microliter volumes of several common solvents, namely, water, methanol, ethanol, and chloroform, with excellent agreement between simulated and experimental results. Furthermore, two types of common acid and alkaline (HCl and NaOH) have been tested at different pH levels. The sensor showed very good sensitivity for pH change and all the results were found to be statistically significant between the pH groups. The SRR was also shown to be highly sensitive to small changes in salt (NaCl) concentrations. Compared to traditional techniques, this miniaturised SRR method is compatible with lab-on-chip approaches. [ABSTRACT FROM AUTHOR]

In cavity-based axion dark matter search experiments exploring high mass regions, multiple-cavity design is under consideration as a method to increase the detection volume within a given magnet bore. We introduce a new idea, referred to as a multiple-cell cavity, which provides various benefits including a larger detection volume, simpler experimental setup, and easier phase-matching mechanism. We present the characteristics of this concept and demonstrate the experimental feasibility with an example of a double-cell cavity. [ABSTRACT FROM AUTHOR]

Abatement of NO using microwave micro-plasma is presented in this paper. The micro-plasma is generated using granular activated carbon (GAC) particles of size (2–3 mm) in loosely fluidized bed in a microwave cavity operated at 2.45 GHz. A single-mode microwave cavity reactor (SMMCR) was constructed and microwave was injected through another slotted single-mode waveguide in a sandwiched manner. COMSOL Multiphysics software was used to investigate the microwave electric field and the power density within the SMMCR. Gas mixture of air and 500 ppm NO (in N2) at the flow rate of 2 l/min was passed through a quartz tube centered within the SMMCR, while the supplied microwave power was very low 10–80 W and corresponding NO reduction was greater than 98%. The mass of GAC used for generating the plasma was 5g. The efficiency of NO reduction is found to be 24.84 g(NO \text{2})/kWh. When air is mixed with NO (in N \text{2}), the efficiency of NOx reduction achieved vary greatly with respect to the supplied microwave energy, and behavior has become complex and is not predictable, which needs further investigation. A gas analyzer (testo 350) was used to measure the gas (NO, NO \text{2}, CO, and O \text{2}) concentration and temperature. [ABSTRACT FROM AUTHOR]

We theoretically investigate a hybrid electro-optomechanical system consisting of an optomechanical cavity and a microwave one. Optomechanical cavity is filled with an optical parametric amplifier, and the system is driven by two optical fields (a pump laser and a weak probe one) and a microwave signal. We describe the dynamics of the system by the Heisenberg-Langevin equations of motion. We show that the presence of the optical parametric amplifier can affect dramatically on the transmission coefficient of the optomechanical cavity at the frequency of the probe field. Also, we demonstrate that the presence of the parametric amplifier can enhance the sensitivity of the system to changing of the input microwave power. Therefore, it is observed that, the parametric amplifier can improve the detection of a weak microwave signal via proposed system. [ABSTRACT FROM AUTHOR]

In this paper, a novel technique to achieve precise temperatures in food sterilization has been proposed. An accurate temperature profile is needed in order to reach a commitment between the total removal of pathogens inside the product and the preservation of nutritional and organoleptic characteristics. The minimal variation of the target temperature in the sample by means of a monitoring and control software platform, allowing temperature stabilization over 100 °C, is the main goal of this work. A cylindrical microwave oven, under pressure conditions and continuous control of the microwave supply power as function of the final temperature inside the sample, has been designed and developed with conditions of single-mode resonance. The uniform heating in the product is achieved by means of sample movement and the self-regulated power control using the measured temperature. Finally, for testing the sterilization of food with this technology, specific biological validation based on Bacillus cereus as a biosensor of heat inactivation has been incorporated as a distribution along the sample in the experimental process to measure the colony-forming units (CFUs) for different food samples (laboratory medium, soup, or fish-based animal by-products). The obtained results allow the validation of this new technology for food sterilization with precise control of the microwave system to ensure the uniform elimination of pathogens using high temperatures. [ABSTRACT FROM AUTHOR]

Refractive index gas thermometry (RIGT) uses the dependence of the relative dielectric permittivity on the density of a noble gas (He), typically measured with a temperature-controlled resonator. On an isotherm, to a good approximation, the slope of the dielectric permittivity versus pressure gives the thermodynamic temperature T . To measure T with a low uncertainty, one must measure the absolute value of the pressure with a low uncertainty and know the compressibility of the resonator wall. This article shows how to use RIGT in a novel way between 5 K and 25 K. Instead of changing the pressure on an isotherm (Schmidt et al., 2007), a constant pressure of pure helium gas is maintained at multiple temperatures. After calibration of the resonator under vacuum at different temperatures, all thermometry is performed at a single pressure and referred to a fixed point of the International Temperature Scale of 1990 (ITS-90) (here the neon triple point at 24.5561 K). The quantity that yields the temperature is the ratio of the resonance frequencies of a microwave mode in the resonator measured at the fixed point and at the unknown temperature. This paper describes the theoretical model of Single-Pressure Refractive Index Gas Thermometry (SPRIGT) and analyses the shifts and broadenings due to non-ideal behaviour. The technique should enable a helium-based measurement of thermodynamic temperature with a resolution better than 25 μK and an uncertainty of around 250 µK. [ABSTRACT FROM AUTHOR]

We describe a dark matter axion detector designed, constructed, and operated both as an innovation platform for new cavity and amplifier technologies and as a data pathfinder in the 5–25 GHz range ( ∼ 20 – 100 μ eV ) . The platform is small but flexible to facilitate the development of new microwave cavity and amplifier concepts in an operational environment. The experiment has recently completed its first data production; it is the first microwave cavity axion search to deploy a Josephson parametric amplifier and a dilution refrigerator to achieve near-quantum limited performance. [ABSTRACT FROM AUTHOR]

In this paper, n-InSe/p-ZnSe/n-InSe (npn) thin-film transistors (TFTs) are deposited onto cubic (111)-oriented Ag, Au, and Al thin-film substrates. The properties of the structures are explored by means of X-ray diffraction and impedance spectroscopy in the frequency range of 10–1800 MHz. Although the Ag, Au, and Al substrates are observed to be well aligned with the cubic ZnSe, the electrical properties of these TFT for the np (InSe/ZnSe) and npn interfaces are different. Namely, while the capacitance of the TFT deposited onto the Ag substrate exhibited positive values, the capacitance of the TFT deposited onto Au and Al films is negative in the range of 10–1100 and 800–1800 MHz, respectively. In addition, even though the impedance of the Ag/np/Ag and Ag/npn/Ag heterojunction monotonically decreased with the increasing frequency, the impedance of Au/np/Au and Au/npn/Au interfaces exhibited resonance peaks at 1211 and 1148 MHz, respectively. When the wave trap features are read from reflection spectra, it is observed that the Ag/npn/Ag and the Al/np/Ag exhibit low-pass filter properties and the Au/npn/Au behaves as a bandstop filter at a notch frequency of 1176 MHz. These properties nominate the npn transistors for use as microwave traps and as high-speed CMOS amplifiers. [ABSTRACT FROM PUBLISHER]

The μ eV-scale axion is a compelling cold dark matter candidate. The Axion Dark Matter eXperiment (ADMX) searches for axions by stimulating the decay of galactic dark matter halo axions into detectable microwave photons by their conversion in a resonant cavity permeated by a strong, static magnetic field. The signal depends on properties of the Milky Way’s dark matter halo; the choice of halo model has significant implications for the sensitivity of direct detection searches, e.g., ADMX. This paper explores the sensitivity of the data taken by ADMX from 2008 to 2010 to various dark matter halo models. New models for the phase-space distribution of local axions are considered; the analysis demonstrates that certain assumptions about the dark matter halo improve limits on axion–photon coupling. In addition, new ADMX data covering 860–892 MHz are included in the analysis. [ABSTRACT FROM AUTHOR]

A systematic study of the electrodynamic coupling between the ferromagnetic resonance (FMR) and the cavity mode of a microwave cavity is presented. The nature of the FMR and cavity modes, described by their resonance position and line width, is measured and compared with a classical model based on the Landau–Lifshitz–Gilbert equation and an RLC circuit, which explicitly implement Faraday’s and Ampère’s laws. The relationship between the coupling gap, which can be accessed experimentally, and the coupling strength, which is a fundamental property of the FMR/cavity system, is discussed on the basis of this model. A straightforward method is experimentally developed to control the coupling gap. The capability of using such a tunable cavity-FMR coupling in combination with spin pumping could provide us with new technologies that utilize the light-matter interaction to control spin current in cavity spintronics. [ABSTRACT FROM PUBLISHER]

A method is established to reliably determine surface conductance of single-layer or multi-layer atomically thin nano-carbon graphene structures. The measurements are made in an air filled standard R100 rectangular waveguide configuration at one of the resonant frequency modes, typically at TE 103 mode of 7.4543 GHz. Surface conductance measurement involves monitoring a change in the quality factor of the cavity as the specimen is progressively inserted into the cavity in quantitative correlation with the specimen surface area. The specimen consists of a nano-carbon-layer supported on a low loss dielectric substrate. The thickness of the conducting nano-carbon layer does not need to be explicitly known, but it is assumed that the lateral dimension is uniform over the specimen area. The non-contact surface conductance measurements are illustrated for a typical graphene grown by chemical vapor deposition process, and for a high quality monolayer epitaxial graphene grown on silicon carbide wafers for which we performed non-gated quantum Hall resistance measurements. The sequence of quantized transverse Hall resistance at the Landau filling factors ν = ±6 and ±2, and the absence of the Hall plateau at ν = 4 indicate that the epitaxially grown graphene is a high quality mono-layer. The resonant microwave cavity measurement is sensitive to the surface and bulk conductivity, and since no additional processing is required, it preserves the integrity of the conductive graphene layer. It allows characterization with high speed, precision and efficiency, compared to transport measurements where sample contacts must be defined and applied in multiple processing steps. [ABSTRACT FROM AUTHOR]

The hafnium doping effects on the performance of the Bi1.5Zn0.92Nb1.5O6.92 (BZN) varicaps are explored by means of impedance and signal power spectroscopes in the range of 10–1800 and 1000–3000 MHz, respectively. The Hf content that was varied in accordance with the Bi1.5Zn0.92–2xHfxNb1.5O6.92 formalism was observed to reach the solubility limit at the Hf content of 0.06. The free carrier concentration in the devices systematically increased with the increasing Hf content. The impedance spectral analysis revealed a series and parallel resonance exchange above 1000 MHz. The critical frequencies of resonance are observed to shift from 1638 to 1585 and reach 1476 MHz as the Hf content increases from 0.00 to 0.03 and reaches 0.06, respectively. It was also observed that the hafnium doping significantly increases the respective dielectric constant of BZN from 268 to 290 and to 470. In addition to the negative dielectric property that is useful in applications where the cancelation of parasitic capacitance is needed, the wave power spectral analysis revealed the microwave band-reject filter properties with the respective notch frequencies of 1580, 1845, and 2040 MHz. While the undoped ceramic filters can detect the signals of power down to 40 nW, the doped ones are functional for the signals of microwatt power. [ABSTRACT FROM AUTHOR]

In this paper, a novel technique to achieve precise temperatures in food sterilization has been proposed. An accurate temperature profile is needed in order to reach a commitment between the total removal of pathogens inside the product and the preservation of nutritional and organoleptic characteristics. The minimal variation of the target temperature in the sample by means of a monitoring and control software platform, allowing temperature stabilization over 100 °C, is the main goal of this work. A cylindrical microwave oven, under pressure conditions and continuous control of the microwave supply power as function of the final temperature inside the sample, has been designed and developed with conditions of single-mode resonance. The uniform heating in the product is achieved by means of sample movement and the self-regulated power control using the measured temperature. Finally, for testing the sterilization of food with this technology, specific biological validation based on Bacillus cereus as a biosensor of heat inactivation has been incorporated as a distribution along the sample in the experimental process to measure the colony-forming units (CFUs) for different food samples (laboratory medium, soup, or fish-based animal by-products). The obtained results allow the validation of this new technology for food sterilization with precise control of the microwave system to ensure the uniform elimination of pathogens using high temperatures.

Herein stacked layers of germanium and selenium oxide are employed to fabricate heterojunction devices that can perform as a multifunctional thin film transistors (TFT). The stacked layers of Ge and SeO 2 are coated onto ultrasonically cleaned glass and Ag thin film substrates using thermal deposition technique under a vacuum pressure of 1.5 × 10 − 4 mbar. The stacked layers are structurally, morphologically, optically and electrically characterized. It is observed that while amorphous germanium films exhibit two energy band gaps of values of 3.56 and 0.78 eV, amorphous SeO 2 show one band gap of 3.70 eV. The conduction and valence band offsets at the Ge/SeO 2 interfaces are 2.24 eV and 0.68 eV, respectively. Optically, the coating of SeO 2 onto Ge films enhanced the light absorbability of SeO 2 by ~ 50 times (at 2.38 eV) and ~17 times (at 1.71 eV) in the visible and infrared ranges of light, respectively. Formation of Ge/SeO 2 is associated with a redshift and blue shift in the values of the energy band gaps of SeO 2 and Ge, respectively. In addition, the current-voltage characteristic curve analyses have shown that Ag/Ge/SeO 2 /Ag TFTs is of tunneling type showing an estimated peak to valley current ratios of 2.0. The TFT displayed additional functionalities presented by PMOS characteristics, microwave resonators, negative capacitance sources and multiband band stop filters. The features of the devices nominate them for use in microwave technology as band stop filters of notch frequencies of 1.10 and 1.53 GHz. [ABSTRACT FROM AUTHOR]

Four decades after its prediction, the axion remains the most compelling solution to the strong- CP problem and a well-motivated dark matter candidate, inspiring a host of elegant and ultrasensitive experiments based on axion-photon mixing. This article reviews the experimental situation on several fronts. The microwave cavity experiment is making excellent progress in the search for dark matter axions in the μeV range and may plausibly be extended up to 100 μeV. Within the past several years, however, researchers have realized that axions are pervasive throughout string theories, but with masses that fall naturally in the neV range, for which an NMR-based search is under development. Both searches for axions emitted from the Sun's burning core and purely laboratory experiments based on photon regeneration have recently made great progress, with ambitious projects proposed for the coming decade. Each of these campaigns has pushed the state of the art in technology, enabling large gains in sensitivity and mass reach. Furthermore, each modality has been exploited in order to search for more generalized axion-like particles, which we also discuss in this review. We are hopeful, even optimistic, that the next review of the subject will concern the discovery of the axion, its properties, and its exploitation as a probe of early universe cosmology and structure formation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon nanotubes purification assisted by microwaves. • Experimental determination of Enthalpy change energy for carbon nanotubes. • Transmission line theory applied to nanostructures modification. Irradiation of multi-wall carbon nanotubes (MWCNT) was performed at different energy densities to characterize structural changes induced by a highly localized 2.45 GHz electric field. For this purpose, a transversal electric (TE 102) resonant microwave cavity was designed and coupled to a standard 800 W microwave oven magnetron. The nanotubes were sealed inside a Pyrex reactor at 10-4 Torr to avoid oxidation or reactions with the environment. Irradiated MWCNT properties were characterized using Raman Spectroscopy, Fourier Transform Infrared Spectroscopy, Thermogravimetry, Solubility tests and Transmission Electron Microscopy. In this work, the energy densities required to modify the MWCNT structure were obtained through an optical method. From an energy density of 82 J/cm3, nanotubes presented nondestructive structural changes, loss of catalytic particles and a decrease of amorphous carbon structures on the surface. A more effective modification with high purity and clearly better structured walls was observed for 167 J/cm3. Furthermore, it was determined that at an energy density of 6.9 KJ/mol a higher purification of MWCNTs is obtained. This value is in agreement with the enthalpy of formation reported for the MWCNTs. This experimental approach could be applied for the functionalization of carbon nanostructures. Finally, the purification process is easily scalable, environmentally friendly and makes maximum use of the irradiated energy. [ABSTRACT FROM AUTHOR]

Hyperthermia is a form of cancer treatment in which affected human tissue is exposed to >40 °C temperature. In this paper, our goal is to assess the efficacy of fullerene agents to reduce heating time for cancer treatment. Such agents can accelerate heating of cancer cells and improve hyperthermia treatment efficacy. Typically, in vitro testing involves cancer cell culturing, heating cell cultures in accordance to specifications, and recording cancer cell viability after hyperthermia. To heat cell cultures, we design and evaluate a 2.4-GHz microwave cavity with controllable temperature. The cavity is comprised of a polystyrene cell culture dish (diameter = 54 mm, height = 13.5 mm) and a printed monopole antenna placed within the cavity for microwave heating. The culture temperature can be controlled through the intensity and duration of the antenna's microwave radiation. Heating experiments were carried out to validate the cavity's performance for F-12K culture medium (Kaighn's F-12K medium, ATCC). Importantly, fullerene agents were shown to reduce heating time and improve hyperthermia treatment efficacy. The culture medium temperature increased, on average, from 24.0 °C to 50.9 °C (without fullerene) and from 24.0 °C to 56.8 °C (with 3 mg/mL fullerene) within 15 minutes. [ABSTRACT FROM AUTHOR]

The axion is a light pseudoscalar particle which suppresses CP-violating effects in strong interactions and also happens to be an excellent dark matter candidate. Axions constituting the dark matter halo of our galaxy may be detected by their resonant conversion to photons in a microwave cavity permeated by a magnetic field. The current generation of the microwave cavity experiment has demonstrated sensitivity to plausible axion models, and upgrades in progress should achieve the sensitivity required for a definitive search, at least for low mass axions. However, a comprehensive strategy for scanning the entire mass range, from 1-1000 μeV, will require significant technological advances to maintain the needed sensitivity at higher frequencies. Such advances could include sub-quantum-limited amplifiers based on squeezed vacuum states, bolometers, and/or superconducting microwave cavities. The Axion Dark Matter eXperiment at High Frequencies (ADMX-HF) represents both a pathfinder for first data in the 20-100 μeV range (~5-25 GHz), and an innovation test-bed for these concepts. [ABSTRACT FROM AUTHOR]

Novel type of finite elements, based on independent three-dimensional higher-order modeling of geometry and electric fields using trivariate B-spline functions, is presented. The method is evaluated in simulations of rectangular, spherical, and ridged canonical microwave cavity problems. The examples demonstrate excellent accuracy and efficiency of the proposed method. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:619-624, 2014 [ABSTRACT FROM AUTHOR]

In the present study, the essential oil from the leaves of River Red Gum (Eucalyptus camaldulensis Dehnh) was distilled by microwave applied in situ hydrodistillation (MWHD) and the properties obtained were compared with hydrodistillation (HD) techniques. The chemical composition of essential oil obtained by the microwave method was analyzed by gas chromatography (GC) and GC–mass spectrometry (MS). The results showed that the essential oil from E. camaldulensis could successfully be distilled by using microwave irradiation power. Microwave power has been supplied from a cavity having a multimode microwave reactor 2455 MHz with a maximum power of 1000 W. Electromagnetic power distribution has been analyzed inside the cavity. The yield of essential oil increased with increasing microwave irradiation power. It was also found that the content of main compounds clearly varied according to methods applied. However, the yield of essential oil determined by MWHD was slightly lower than that of conventional HD method at conditions studied. [ABSTRACT FROM PUBLISHER]

Abstract: We review the use of mechanical oscillators in circuit quantum electrodynamics. The capacitive coupling of nano-electromechanical systems with quantum bits and superconducting microwave resonators gives rise to a rich quantum physics involving electrons, photons and phonons. We focus in particular on the linear coupling between a mechanical oscillator and a microwave resonator and present the quantum dynamics that stems from the phonotonic Josephson junction. The microwave cavity turns out to be a powerful device to detect quantum phonon states and manipulate entangled states between phonons and photons. [Copyright &y& Elsevier]

The performance of a novel microwave ignition source was experimentally tested against a standard multi-spark ignition system. Comparison of the combustion and detonation performance was measured. The growth of combustion kernels and the discharge pattern of the igniters were recorded using high-speed video cameras for visual comparison. The results showed that the transition of deflagration to detonation transition was comparable between the two ignition systems. Significant improvement in ignition of lean mixtures of ethylene and ethane were observed for the microwave ignition system over the baseline multi-spark ignition and thus should be considered for application as a lean ignition source. [ABSTRACT FROM AUTHOR]

Abstract: The Axion Dark Matter eXperiment (ADMX) was designed to detect ultra-weakly interacting relic axion particles by searching for their conversion to microwave photons in a resonant cavity positioned in a strong magnetic field. Given the extremely low expected axion–photon conversion power we have designed, built and operated a microwave receiver based on a Superconducting QUantum Interference Device (SQUID). We describe the ADMX receiver in detail as well as the analysis of narrow band microwave signals. We demonstrate the sustained use of a SQUID amplifier operating between 812 and 860MHz with a noise temperature of 1K. The receiver has a noise equivalent power of in the band of operation for an integration time of . [Copyright &y& Elsevier]