Using density functional theory (DFT), the electronic structure, lattice parameters, magnetic and thermodynamic properties of TlIn1–xCrxS2 with a monoclinic system were calculated. The influence of the degree of doping with chromium impurities on the properties of TlIn1–xCrxS2 supercells has been studied. Calculations were carried out using ab initio methods in the local electron density approximation (LDA) and in the generalized gradient approximation (GGA). Spin-orbit and Coulomb interactions were taken into account in DFT calculations. A change in the concentration of chromium impurity (x = 0.001–0.02) in TlInS2 does not lead to a change in the equilibrium lattice parameters and the type of magnetic ordering in TlIn1–xCrxS2. Phase equilibria and stability of binary and ternary compounds were studied by the thermodynamic method and the functional DFT GGA method in the Tl–In–S ternary system. The constructed isothermal section of the phase diagram at 298 K confirms the insignificant region of homogeneity, based on intermediate ternary compounds, of the Tl–In–S system.The formation energies of the compounds TlInS2 and TlIn1–xCrxS2 (x = 0.001–0.02) were calculated by the DFT method and are thermodynamically consistent with each other. The energy of formation of the TlInS2 compound, calculated by theoretical methods, is also consistent with experimental data. This indicates the adequacy of the calculation models used. In order to determine stable doping conditions, we analyzed the thermodynamic properties of the phases of the Tl–In–S system, established stable states of multicomponent phases, stable equilibria between binary and ternary compounds of the TlIn1–xCrxS2 system. Polycrystals were synthesized and TlIn1–xCrxS2 single crystals with different chromium impurity concentrations (x = 0, 0.001 and 0.02) were grown from them. The crystal structure, thermodynamic, dielectric, electrical and dosimetric characteristics of TlIn1–xCrxS2 single crystals were studied. The calculated thermodynamic and physical properties of the TlIn1–xCrxS2 phases are compared with experimental data.

This work is a continuation of our research [1], aimed at developing methods for high-precision control of multilevel quantum systems (qudits). This study presents a method for precision quantum measurements of such systems using fuzzy quantum measurements. The developed method is used for precision reconstruction of quantum states under conditions of significant influence of amplitude and phase relaxation. The protocols of quantum measurements based on mutually unbiased bases of various dimensions are considered. The accuracy characteristics of sets of random states uniformly distributed with respect to the Haar measure are studied. A study was made of the dependence of the accuracy loss function on the parameters of phase and amplitude relaxation. It is shown that the results of the performed numerical experiments are in good agreement with the analytical results obtained on the basis of the universal distribution of accuracy losses using fuzzy measurement protocols.

На примере распределений Пирсона IV типа предложена процедура дополнения классического распределения вероятностей до квантового состояния. Получена волновая функция, отвечающая распределениям Пирсона IV типа, а также построен соответствующий набор базисных функций. Продемонстрировано применение разработанного метода к задачам статистического анализа данных и квантовой механики. Показана эффективность разработанного подхода при аппроксимации статистических распределений с тяжелыми хвостами.

— The creation of an electronic component base based on microelectromechanical systems is one of the main directions of the development of modern microelectronics and the basis for the construction of a new generation of radar and communication systems. This is due to the possibility of obtaining fundamentally new electrophysical properties of devices obtained on the basis of microsystem technology. Classification of devices based on microsystem technology includes: switches, varactors, resonators, actuators, filters, etc. Currently, the most widely used radio frequency MEMS switches. This is due, in particular, to the linearity of the transmission characteristics of radio frequency signal switches in a wide frequency range. Radio frequency devices built on the basis of microsystem technology have a good level of isolation (>30 dB) and low insertion losses (<0.5 dB). One of the factors that have a significant impact on the operation of the RF MEMS switch is the choice of materials. The design of the RF MEMS switch consists of the following main elements: substrate, conducting lines, dielectric, beam structures. The choice of materials for each of the listed elements is important, but the substrate material has the most significant effect on the operation of the RF MEMS switch.

Quantum measurements play a crucial role in the field of quantum computing and quantum information processing. However, these measurements are susceptible to errors, which can compromise the accuracy and reliability of the collected statistics. In this work, we address this challenge by leveraging a Fuzzy measurements mathematical model for quantum measurement error correction. Building upon previous work dedicated to the development of the fuzzy mathematical model, which was primarily focused on quantum tomography of ion qubits, we extend its applicability to correct statistics obtained from quantum measurements in general. Rather than analyzing the sources and characteristics of readout errors, we calculate the readout errors using preliminary measurements. By utilizing these calculated errors, we derive corrections that effectively mitigate these errors. We demonstrate the efficiency of our approach through numerical simulations. Our correction approach is applicable to quantum computing platforms that rely on statistical quantum measurements, providing a practical solution for improving the accuracy of quantum data analysis. This work builds upon previous research and contributes to the development of robust techniques for accurate statistical analysis in quantum systems.

Using an example of Pearson type IV distributions, we propose a procedure of completing the classical probability distribution to a quantum state. We obtain a wave function corresponding to Pearson type IV distributions and construct the corresponding set of basis functions. Then we demonstrate how the developed method applies to problems of statistical data analysis and quantum mechanics, and show the efficiency of our approach for the problem of approximating statistical distributions with heavy tails.

Using geometrically optimized supercells TlInS_2 and TlInS_2⟨Yb⟩ and density functional theory (DFT), the electronic properties of the samples have been calculated. The enthalpy of formation of TlInS_2 has been also calculated. It has been determined that TlInS_2 has a layered monoclinic system with sp. gr. C2/c— 1pt C_2h^6 . The frequency dispersion of the dielectric loss tangent ( tanδ ), real ( ε 1pt ' ), and imaginary ( ε 1pt” ) components of complex dielectric constant, and conductivity in alternating electric fields (ac-conductivity, σ_ac ) across layers in the frequency range f = 5 × 104–3.5 × 107 Hz have been studied. In the frequency range f = 5 × 104–2.4 × 107 Hz ac-conductivity of a single crystal TlInS_2⟨1 at % Yb⟩ has obeyed the law σ_ac ∼ f^0.8 , characteristic of hopping conductivity of charge carriers on states lying in the vicinity of the Fermi level. The density and energy spread of states near the Fermi level, the average time and distance of jumps, and the concentration of traps responsible for conductivity have been estimated for TlInS_2⟨1 at % Yb⟩ at alternating current.

На геометрически оптимизированных суперъячейках T1InS2 и T1InS2 Yb с использованием теории функционала плотности (DFT) рассчитаны электронные свойства образцов. Рассчитана также энтальпия образования T1InS2. Установлено, что T1InS2 имеет слоистую моноклинную сингонию с пространственной группой C2/c–C2h6 . В образцах изучена частотная дисперсия тангенса угла ди­электрических потерь (tgδ), действительной (ε′) и мнимой (ε″) составляющих комплексной диэлектрической проницаемости и проводимости в переменных электрических полях (ac-проводимость – σac) поперек слоев в области частот f = 5 × 104–3.5 × 107 Гц. В диапазоне частот f = 5 × 104–2.4 ×107 Гц ac-проводимость монокристалла T1InS2 1 ат% Yb подчинялась закономерности σac ∼f 0.8, характерной для прыжковой проводимости носителей заряда по состояниям, лежащим в окрестности уровня Ферми. Оценены плотность и энергетический разброс состояний вблизи уровня Ферми, среднее время и расстояние прыжков, концентрация ловушек, ответственных за проводимость T1InS2 1 ат% Yb на переменном токе.

The T–x phase diagram of the quasi-binary system Li2O–TiO2 was refined and the isothermal cross section of the ternary Li–Ti–O system at 298 K was constructed. The equilibrium phase regions of Li–Ti–O in the solid state are determined with the participation of boundary binary oxides and four intermediate ternary compounds , , and . Using the density functional theory (DFT LSDA) method, the formation energies of the indicated ternary compounds of the Li2O–TiO2 system were calculated and the dependence of on the composition was plotted. Ab initio modeling of supercells based on M-doped anode material based on the (LTO) compound with a monoclinic structure () was carried out. It has been shown that partial substitution of cations and oxygen in the m-LTO–M structure increases the efficiency of a lithium-ion battery (LIB) both by stabilizing the structure and by increasing the diffusion rate of . Due to the contribution of d-orbitals (Zr4+-4d, Nb3+-4d orbitals) to the exchange energy, partial polarization of electronic states occurs and the electronic conductivity of m-LTO–M increases. The formation of oxygen vacancies in the m-LTO–M crystal lattice, as in binary oxides, can create donor levels and improve the transport of and electrons. M-doping of the m-LTO structure by replacing cations, in particular lithium, with Zr or Nb atoms noticeably reduces the band gap (Eg) of m-LTO–M supercells. In this case, in the m-LTO–M band structure, the Fermi level shifts to the conduction band and the band gap narrows. Decreasing the Eg value increases the electronic and lithium-ion conductivity of m-LTO–M supercells.

The adsorption, electronic, and thermodynamic properties of the 2 × 2 × 1 and 3 × 3 × 1 supercells of the binary compounds ( A_nB_m = 4H- SiC, α 1pt - 1ptLi_2C_2, Li_nSi_m ) of the Si–C–Li system were studied using the density functional theory (DFT). The theoretical capacity of the 4H–SiC hexagonal polytype was found to exceed that of graphite (370 mA h/g) used as an anode material for lithium-ion batteries. The crystalline compounds A_nB_m have electronic conductivity. The DFT calculations used the exchange-correlation functional within the framework of the generalized gradient approximation (GGA PBE). The parameters of the crystal structure, the adsorption energy of the Li_ads adatom on the 4H–SiC substrate, the electronic band structure, and the thermodynamic properties of the supercells of A_nB_m compounds were calculated. The thermodynamically favorable position of Li_ads and the stable configuration of the 4H–SiC〈Liads〉 supercells were determined. The DFT calculations of the enthalpy of formation of A_nB_m compounds in the Si–C–Li ternary system were performed. The calculated characteristics of A_nB_m agree with the experimental data. The equilibrium connodes in the concentration triangle of Si–C–Li were established using the standard thermodynamic potentials of A_nB_m compounds and the changes in energy in solid-phase exchange reactions between these compounds. An isothermal section of the phase diagram of Si–C–Li at 298 K was constructed.

In the equilibrium model of the solid surface–adatom system, including a three-dimensional interfacial surface, changes in surface properties are considered, taking into account the chemical potential due to the action of surface tension. The relationship between chemical potential and electrochemical potential of the ith component in an electrochemical cell is analyzed. Using the density functional theory (DFT), the adsorption, electronic, and thermodynamic properties of 2 × 2 × 1 and 3 × 3 × 1 supercells of crystalline compounds AmBn, (, where n and m are stoichiometric coefficients) of the boundary binary systems of the ternary phase diagram of Si–C–Li are studied. The stability of phases AmBn and property calculations are carried out with the exchange-correlation functional within the framework of the generalized gradient approximation (GGA PBE). The parameters of the crystal structures of the compounds AmBn, the adsorption energy of the lithium adatom on a 4H–SiC substrate, the electronic structure, and the thermodynamic properties of supercells are calculated. The thermodynamically stable configurations of the 4H–SiC–Liads supercells having different locations Liads are determined. The DFT GGA PBE calculations of the enthalpy of formation of compounds AmBn are carried out in the ternary Si–C–Li system. Taking into account the changes in the Gibbs free energy in the solid-phase exchange reactions between binary compounds, equilibrium sections (connodes) in the concentration triangle of the Si–C–Li phase diagram are established. An isothermal section of the Si–C–Li phase diagram at 298 K is constructed. The patterns of diffusion processes that are related to the movement of particles on the surface layer of the 6H–SiC sample are analyzed. The activation energy of lithium diffusion in 6H–SiC is calculated from the Arrhenius type relation in two temperature ranges (769–973 K) and (1873–2673 K).

The investigation of the influence of RF MEMS switch design on frequency characteristics is presented. The design of a hybrid RF MEMS switch was proposed, which allows to significantly increase the switching capacity, as well as to reduce the signal loss within the frequencies from 100 MHz up to 10 GHz. Proposed hybrid RF MEMS switch is enable to be used in new generation radar and communication systems.

The etching of silicon in CBrF3 plasmas has been examined in a wide pressure range (2–100Pa). Conditions for the high quality trenches were determined. F, Br, C and 0 surface contaminations and surface lattice damage were estimated by RBS measurements. The aperture effect was analyzed.

Multilevel quantum states (qudits) represent a promising platform for scalable quantum computing. In this paper, we present a method for precisely controlling such systems using fuzzy quantum measurements. The developed method is used for a precise reconstruction of quantum states under conditions of a significant effect of decoherence and quantum noise. Protocols for quantum measurements based on mutually unbiased bases (MUBs) of various dimensions are considered. The accuracy characteristics of sets of random states uniformly distributed with respect to the Haar measure are studied.

Based on the density functional theory (DFT) with allowance for spin polarization or the local spin density approximation (LSDA), we calculate the adsorption and diffusion properties of a lithium atom on a graphene ( GP ) monolayer with monovacancy ( GP_V ) as the anode material for an Li -ion battery. The DFT LSDA calculations are performed in relaxed 5 × 5 and 6 × 6 GP- Li_ads supercells and based on graphene with the monovacancy + lithium adatom complex GP_V- Li_ads . Based on the calculated values of the adsorption energy of the lithium atom E_ads^Li , the energetically stable location of the lithium adatom Li_ads is determined on a monolayer of supercells in GP- Li_ads and GP_V- Li_ads . The calculation results show that the Li_ads adatom energetically prefers to be adsorbed in the pit position (H-site) rather than adsorbed from above (T-site) of the carbon atom in the monolayer. The DFT LSDA calculated electronic band structure and local total and partial magnetic moment of GP- Li_ads supercell atoms are consistent with the calculations performed by the generalized gradient approximation (GGA)-PBE functional for the H-, B-, and T-sites of graphene. Taking into account the experimentally obtained diffusion coefficients of lithium in two-layer graphene in the structural packing of an AB package and the temperature (263–333 K) dependence of Li diffusion in two-layer graphene, which is described by the Arrhenius law, the diffusion activation energy of Li is calculated at concentrations of x = 0.06–0.51 in LixC12 graphene in the AB packaging.

Using numerical simulation methods that take into account the dead time effect, algorithms are developed to calculate the detector’s response for photon fluxes with different photon number distributions, including the Poisson, Fock, and thermal distributions. Based on the results obtained, a detector tomography method is developed, as well as an algorithm for identifying the corresponding elements of a positive operator-valued measure (POVM). Experimental studies using coherent states demonstrate close agreement between the calculation results and experimental data.

We develop a new method for high-precision tomography of ion qubit registers under conditions of limited distinguishability of logical states. It is not always possible to achieve low error rates during the readout of the quantum states of ion qubits due to the finite lifetime of excited levels, photon scattering, detector dark counts, low numerical aperture, etc. However, the model of fuzzy quantum measurements makes it possible to ensure precise tomography of quantum states. To do this, we developed a fuzzy measurement model based on counting the number of fluorescent photons. A statistically adequate algorithm for the reconstruction of quantum states of ion qubit registers based on fuzzy measurement operators is proposed. The algorithm uses the complete information available in the experiment and makes it possible to account for systematic measurement errors associated with the limited distinguishability of the logical states of ion qubits. We show that the developed model, although computationally more complex, contains significantly more information about the state of the qubit and provides a higher accuracy of state reconstruction compared to the model based on the threshold algorithm.

The local environment of atoms in a semiconductor compound TlInTe2 with tetragonal syngony is studied by the density functional theory (DFT). The introduction of a point defect (indium vacancies) into the TlInTe2 lattice is modeled using supercells. The DFT electronic properties (total and local partial densities of states (PDOS) of electrons) are modeled for the primitive TlInTe2 cell (16 atoms per unit cell) and for the defective TlInTe2 - V_In cell (where V_In is the vacancy In) consisting of 32 atoms. The DFT-GGA calculations of the TlInTe2 - V_In band structure show that the band gap ( E_g ) is E_g = 1.21 eV. This value is significantly different from the experimental value. The Hubbard model is used to correct the interaction of particles in the lattice. The DFT-GGA + U (U is the Hubbard potential) calculated by the TlInTe2 - V_In band gap is E_g = 0.97 eV. For the TlInTe2 - V_In supercell, the energies of the formation of a vacancy, the chemical potential of indium, and the standard enthalpy of the formation of TlInTe2 are calculated. When explaining the effect of various factors on the transport phenomena in TlInTe2, their thermal and electrical conductivity, both the DFT-calculated data and experimental data, are used. Taking into account the experimental data for the p‑TlInTe2 crystals, the mechanism of conduction in the direction of structural chains (c axis of the crystal) is established. From the experimental data in the temperature range T = 148–430 K, the band gap E_g = 0.94 eV and the activation energy of impurity conduction E_t = 0.1 eV (at 210–300 K) are estimated. At temperatures of T ≤ 210 K, DC hopping conduction takes place in the p-TlInTe2 crystals. With this in mind, the following physical parameters are calculated for p-TlInTe2: the density of states localized near the Fermi level, their energy spread, and the average hopping distance.

Cryogenic etching of silicon in SF6/O2 plasma is the process of choice for fabrication of deep high aspect ratio structures with strict requirements for sidewall angle, surface roughness and contamination, including MEMS, X-ray optics, and supercapacitors. The manufacturing of such structures, containing features of various size and shape, poses new challenges for the etching process optimization, since the key parameters of the resulting structures depend on the local aspect ratio and the shape of the mask aperture. As an aid in process optimization, we propose a three-dimensional Monte-Carlo simulator for the cryogenic etching of complex structures. It employs a surface kinetics model tuned to SF6/O2 process in 2 1⁄2D geometry and cubic voxel representations of simulation domain. Systematic study on cryogenic etching of test structures of different mask shape and aspect ratio is performed and principal mechanisms affecting etching results are identified.

The results of studying the electronic structure and the influence of the local environment of the copper impurity on the properties and magnetic moment in supercells in Zn1-xCuxO are presented. DFT calculations were carried out in the local electron density (LDA) and generalized gradient approximation (GGA). The band structure of in Zn1-xCuxO was calculated taking into account the correction for spin polarization and the strong electronic interaction. DFT LSDA + U and SGGA + U (U is the Coulomb interaction) calculations made it possible to take into account the contributions of the 3d shells of the Zn and Cu cations to the band spectrum of in Zn1-xCuxO. The introduction of copper into the ZnO lattice leads to a change in the impurity and valence bands of in Zn1-xCuxO. In this case, the bottom of the in Zn1-xCuxO conduction band shifts towards low energies. The total density of electronic states of in Zn1-xCuxO near the Fermi level is mainly determined by the 3d states of Zn and Cu and the 2p state of oxygen. ZnO doped with copper acquires a magnetic moment. The introduction of a vacancy into a supercell in Zn1-xCuxO noticeably changes the local magnetic moment. As the copper concentration in Zn1-xCuxO (x=0, 0.01, and 0.02) increases, the conductivity of the samples in both constant and alternating current increased, and the activation energy of conduction decreased. Keywords: ZnO, copper doping, density functional theory, band calculations, electronic structure, localized magnetic moment, defect formation energies, Zn1-xCuxO, charge transfer, parameters of localized states.