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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]