Quantum Electronics

Spintronics, or spin electronics, represents a transformative shift in the field of electronics, moving beyond the exclusive use of electron charge to exploit the intrinsic spin and associated magnetic moment of electrons. This approach promises devices that are faster, smaller, more energy-efficient, and capable of novel functionalities that conventional charge-based systems cannot achieve. This paper explores the principles underlying electron spin behavior, the mechanisms of spin injection, transport, and detection, and the applications of spintronics in memory storage, logic devices, and quantum computing. It also examines the limitations and challenges facing spintronic technologies, such as spin coherence and material constraints, while projecting their milestone potential to redefine the future of computing. The findings suggest that spintronics may play a role as significant as the transistor revolution of the 20th century, potentially shaping the next era of information technology.

The nonlinear effect of parametric oscillatory instability in the gravitational wave laser detector (antenna) is considered as a factor that considerably reduces the sensitivity of the device. It is shown that in an antenna with a circulating power above a certain threshold value there occurs excitation of Stokes optical modes in the Fabry ë Perot resonators and of test mass elastic modes. Parametric oscillatory instability in gravitational wave interferometers of the second (LIGO, Virgo, LCGT, GEO-600) and third (ET ì Einstein Telescope) generation with different types of pump is examined. The effect discussed has been observed not only in gravitational wave laser interferometers, but also many times in other opto-mechanical systems. All current methods for suppressing parametric oscillatory instability in gravitational wave interferometers are also discussed, both passive and active.

In this paper, we derive a divergent form of the force balance equation for collisionless plasma in the quasineutrality approximation, in which the electric field and current density are excluded. For a stationary spatially one-dimensional current sheet with a constant normal component of the magnetic field and magnetized electrons, the general form of the force balance equation has been obtained for the first time in the form of a conservation law. An equation in this form is necessary for the correct formulation of boundary conditions when modeling asymmetric current sheets, as well as for the control of the stationarity of the numerical solution obtained in the model. Furthermore, the fulfillment of this equation is considered for two types of stationary configurations of a thin current sheet, which are obtained using a numerical model. The derived equation makes it possible to develop models of asymmetric current sheets, in particular current sheets on the magnetopause flanks in...

This paper is both a review of some recent developments in the utilization of magnetism for applications to logic and memory and a description of some new innovations in nanomagnetics and spintronics. Nanomagnetics is primarily based on the magnetic interactions, while spintronics is primarily concerned with devices that utilize spin polarized currents. With the end of complementary metal-oxidesemiconductor (CMOS) in sight, nanomagnetics can provide a new paradigm for information process using the principles of magnetic quantum cellular automata (MQCA). This paper will review and describe these principles and then introduce a new nonlithographic method of producing reconfigurable arrays of MQCAs and/or storage bits that can be configured electrically. Furthermore, this paper will provide a brief description of magnetoresistive random access memory (MRAM), the first mainstream spintronic nonvolatile random access memory and project how far its successor spin transfer torque random access memory (STT-RAM) can go to provide a truly universal memory that can in principle replace most, if not all, semiconductor memories in the near future. For completeness, a description of an all-metal logic architecture based on magnetoresistive structures (transpinnor) will be described as well as some approaches to logic using magnetic tunnel junctions (MTJs). KEYWORDS | Magnetic cellular automata (MCA); magneto- resistive random access memory (MRAM); reconfigurable array of magnetic automata (RAMA); spin transfer torque random access memory (STT-RAM) Manuscript

We review our recent efforts in building atom-scale quantumdot cellular automata circuits on a silicon surface. Our building block consists of silicon dangling bond on a H-Si(001) surface, which has been shown to act as a quantum dot. First the fabrication, experimental imaging, and charging character of the dangling bond are discussed. We then show how precise assemblies of such dots can be created to form artificial molecules. Such complex structures can be used as systems with custom optical properties, circuit elements for quantum-dot cellular automata, and quantum computing. Considerations on macro-to-atom connections are discussed.

Breast cancer has become a major cause of death among women. The lifetime risk of a woman developing this disease has been established as one in eight. The most useful way to reduce breast cancer death is to treat the disease as early as possible. The existing methods of early diagnostics of breast cancer are mainly based on screening mammography or Magnetic Resonance Imaging (MRI) periodically conducted at medical facilities. In this paper the authors proposing a new approach for simple breast cancer detection. It is based on skin stimulation by sound waves, illuminating it by laser beam and tracking the reflected secondary speckle patterns. As first approach, plastic balls of different sizes were placed under the skin of chicken breast and detected by the proposed method.

We have measured the temperature dependence of the conductivity σxx of a two-dimensional electron system deep into the localized regime of the quantum Hall plateau transition. Using variable-range hopping theory we are able to extract directly the localization length ξ from this experiment. We use our results to study the scaling behavior of ξ as a function of the filling factor distance |δν| to the critical point of the transition. We find for all samples a power-law behavior ξ ∝ |δν| -γ with a universal scaling exponent γ = 2.3 as proposed theoretically.

We have studied the structure and dipole charge-density response of nanorings as a function of the magnetic field using local-spin-density-functional theory. Two small rings consisting of 12 and 22 electrons confined by a positively charged background are used to represent the cases of narrow and wide rings. The results are qualitatively compared with experimental data existing on microrings and on antidots. A smaller ring containing five electrons is also analyzed to allow for a closer comparison with a recent experiment on a two-electron quantum ring. ͓S0163-1829͑99͒02723-X͔

We have employed time-dependent local-spin density-functional theory to analyze the multipole spin and charge density excitations in GaAs-Al x Ga 1Ϫx As quantum dots. The on-plane transferred momentum degree of freedom has been taken into account, and the wave-vector dependence of the excitations is discussed. In agreement with previous experiments, we have found that the energies of these modes do not depend on the transferred wave vector, although their intensities do. Comparison with a recent resonant Raman scattering experiment ͓C. Schu ¨ller et al., Phys. Rev. Lett. 80, 2673 ͑1998͔͒ is made. This allows us to identify the angular momentum of several of the observed modes as well as to reproduce their energies. The dipole longitudinal response of quantum dots has been recently addressed in detail. We sketch here how the method can be generalized to deal with other multipolarities and the wave-vector degree of freedom. The first task is to obtain the ground state ͑gs͒ of the dot

We have developed a low-cost, miniaturized laser heterodyne radiometer for highly sensitive measurements of carbon dioxide (CO 2 ) in the atmospheric column. In this passive design, sunlight that has undergone absorption by CO 2 in the atmosphere is collected and mixed with continuous wave laser light that is step-scanned across the absorption feature centered at 1,573.6 nm. The resulting radio frequency beat signal is collected as a function of laser wavelength, from which the total column mole fraction can be de-convolved. We are expanding this technique to include methane (CH 4 ) and carbon monoxide (CO), and with minor modifications, this technique can be expanded to include species such as water vapor (H 2 O) and nitrous oxide (N 2 O).

Infinite-dimensional port-Hamiltonian representation of irreversible processes accounting for the thermal energy domain is presented. Two examples are studied: the transmission line and a non-isothermal reaction diffusion process. The proposed approach uses thermodynamic variables in order to define the infinite-dimensional interconnection structure linking the different phenomena. A presentation is given for one-dimensional spatial domain. For the transmission line, the Hamiltonian is the total energy and for the reaction diffusion process it is the enthalpy or the opposite of entropy.

We report the experimental observation of quantized conductance by Rashba bands at the surface of 50-nm Bi nanowires. With increasing magnetic fields along the wire axis, the wires exhibit a stepwise increase of conductance with as many as four distinct plateaus together with oscillatory thermopower. The observations can be accounted for by the increase of the number of propagating surface modes. The modes have very high mobility and are associated with Aharonov-Bohm interference around the perimeter consistently with theory of quasiballistic one-dimensional nanowires considering that Lorentz forces decouple the modes from scattering at the nanowire surface.

We have observed the intensity fluctuations of the F =2 87 Rb atom laser at low output coupling rate. Theoretically, we find that the atom loss of the condensate due to the output of atom laser leads to fluctuations of the laser pulses, which is inherent in all state changing out-coupling such as rf and Raman. Another reason leading to large fluctuations is the interference of output pulses.

Being an atomically thin material, graphene is known to be extremely susceptible to its environment, including defects and phonons in the substrate on which it is placed as well as gas molecules that surround it. Thus, any device design using graphene has to take into consideration all surrounding components, and device performance needs to be evaluated in terms of environmental influence. However, no methods have been established to date to readily measure the density and distribution of external perturbations in a quantitative and non-destructive manner. Here, we present a rapid and non-contact method for visualizing the distribution of molecular adsorbates on graphene semi-quantitatively using terahertz time-domain spectroscopy and imaging. We found that the waveform of terahertz bursts emitted from graphene-coated InP sensitively changes with the type of atmospheric gas, laser irradiation time, and ultraviolet light illumination. The terahertz waveform change is explained throug...

Silicon photonics has attracted significant interest in recent years due to its potential in integrated photonics components 1,2 as well as all-dielectric meta-optics elements. Strong photon-photon interactions, aka optical nonlinearity, realizes active control of aforementioned photonic devices. However, intrinsic nonlinearity of Si is too weak to envision practical applications. To boost the nonlinear response, long interactionlength structures such as waveguides, or resonant structures such as microring resonators or photonic crystals have been adopted. Nevertheless, their feature sizes are typically larger than 10 μm, much larger than their electronic counterparts. Here we discover, when reducing the size of Si resonator down to ~100 nm, a giant photothermal nonlinearity that yields 400% reversible and repeatable deviation from linear scattering response at low excitation intensity (mW/μm 2 ). The equivalent nonlinear index n2 at nanoscale is five-order larger than that of bulk, due to Mie resonance enhanced absorption and high-efficiency heating in the thermally isolated nanostructure. In addition, the nanoscale thermal relaxation time reaches nanosecond, implying GHz modulation speed. This large and fast nonlinearity enables applications toward all-optical control in nanoscale, as well as super-resolution imaging of silicon.

Silicon photonics has attracted significant interest in recent years due to its potential in integrated photonics components (1,2) as well as all-dielectric meta-optics elements.(3) Strong photon-photon interactions, aka optical nonlinearity, realizes active control of aforementioned photonic devices.(4,5) However, intrinsic nonlinearity of Si is too weak to envision practical applications. To boost the nonlinear response, long interaction-length structures such as waveguides, or resonant structures such as microring resonators or photonic crystals have been adopted.(6,7) Nevertheless, their feature sizes are typically larger than 10 $\mu$m, much larger than their electronic counterparts. Here we discover, when reducing the size of Si resonator down to ~100 nm, a giant photothermal nonlinearity that yields 400% reversible and repeatable deviation from linear scattering response at low excitation intensity (mW/$\mu$m$^2$). The equivalent nonlinear index n$_2$ at nanoscale is five-ord...

We analyse the ideal shear resistances of 15 nonequivalent slip systems in β-Sn using first-principles density functional theory. From the ideal shear resistance and Schmid's law, the orientation dependence of active slip systems in a β-Sn single crystal subjected to uniaxial tension is investigated. We find that (1 0 1)[ 1 0 1] has the lowest ideal shear resistance among the 15 slip systems. Our calculations indicate that, depending on crystal orientation, uniaxial tension activates seven nonequivalent groups of slip systems. The active slip systems for [1 0 0] and [1 1 0] orientations determined in this study agree with the experimental results.

In this paper, a comparative analysis of two approaches to synthesis 2D hologram, which restores optical field without conjugated images, is performed. These holograms are used in embossed rainbow protective holograms to improve their forgeryproof characteristics. As a basis, one method of kinoform hologram synthesis is used, which allows to obtain the restored image of acceptable quality, but phase-matching condition is necessary to complete. That limits usage of this method in mass production of embossed holograms. The offered method of combined holograms is based on addition of optical fields restored by separated Fourier holograms. This method let us to avoid hard requirements to technical process on resist -polymer relief translating accuracy. Thus, the proposed method can be recommended for application in mass production of rainbow protective holograms.

We have studied a Bose-Einstein condensate of $^{87}Rb$ atoms under an oscillatory excitation. For a fixed frequency, we observe the formation of different structures in the cloud as a function of two parameters: time and amplitude of the excitation. Our results are summarized in a diagram of amplitude versus time in which we identify four zones exhibiting different behaviors. We concentrate on the regimes generated by the larger values of the parameters of the excitation, which we identify as the turbulent and granular regimes. We also present simulations based on the Gross-Pitaevskii equation which show the overall behavior of the diagram, supporting our observations.

In recent years cellular automata (CAs) have been used widely to model and simulate physical systems and also to solve scientific problems. CAs have also been successfully used as a VLSI architecture and have proved to be very efficient at least in terms of silicon-area utilisation and clock-speed maximisation. Quantum cellullar automata (QCA) is one of the promising emerging technologies for nanoscale circuit implementation. QCA technology provides very high scale integration, very high switching frequency and very low power circuit characteristics. In the work reported here, a universal cellular automaton cell has been designed using QCA circuitry. The implementation of CAs using QCA nanoelectronic circuits not only drives the already developed systems based on CAs to the nanoelectronics era but improves their performance significantly.

The plasma front propagation regimes and the spectral characteristics of plasma emission upon laser breakdown in the normal atmosphere are experimentally investigated. The molecular emission of atmospheric gases is recorded at the initial instants of the development of the laser plasma. The behaviour of the intensities of continuous and line emission spectra is investigated upon interaction of counterpropagating plasma fronts; in this case, an increase in the integrated intensity of the plasma emission and a rise in the contrast of emission lines against the background of continuous plasma emission was recorded.

The interaction and recovery of deformation induced defects has been studied by positron annihilation techniques in the Al-1.7at.% Li and AI-9.9 at.% Li alloys. The samples have been deformed at liquid nitrogen and room temperatures for several deformation degrees. In the low temperature region (lC0-200 K and 2 " K) the two recovery stages observed in pure Al and phenomena currently interpreted as divacancy and monovacancy migration are present in both alloys. However, it is observed that the presence of Lienhancesthevacancyc1ustering.Theeffect observedinthe high temperature region (400-600K) in the higher Li content aUoy has been interprzted as trapping of positrons by 6' particles.

In quantum mechanics (QM) the theory of quantum transitions works only in atomic physics and in the adiabatic approximation (AA) in molecular and chemical physics. To restore the functionality of QM in molecular and chemical physics beyond AA, Egorov is forced to introduce the so-called dozy chaos (DC) into QM. DC is introduced by replacing the infinitesimal imaginary additive in the energy denominator of the total Green's function of the system with a finite value. As a result, the transition between quantum states taken in AA becomes continuous, and QM itself becomes quantum-classical mechanics (QCM). In the case of strong DC, QCM leads to the same results as QM. In the case of weak DC, a regular component in the transient state dynamics appears against the background of chaos. The coherent interaction of the regular component in the electron charge motion and the regular component in the reorganization motion of the nuclei in the environment leads to the so-called Egorov resonance (ER). The same chaos can be strong for small molecules (standard optical spectroscopy) and weak for large molecules (photochemistry and nanophotonics). Therefore, ER is also called nanoresonance. ER explains the nature of the well-known narrow and intense optical J-band of J-aggregates of polymethine dyes, discovered by Jelley and Scheibe in 1936. The first explanation of the nature of the J-band was given by Franck and Teller in 1938 based on the Frenkel exciton concept. This article discusses in detail the evolution of theoretical ideas about the nature of the J-band over almost a century of history and provides a deeply reasoned criticism of them. On the basis of QCM it is explained a large number of experimental data on the shape of optical bands in polymethine dyes and their aggregates. The nature of the physical source of life, possible alternative life forms and the idea of living materials are discussed.

Изобретение относится к области инерциальной навигации, гироскопических измерений и автоматического управления, а именно — к способам фазовой синхронизации между гироскопами, входящими в состав рой-систем или распределённых мультиагентных инерциальных комплексов. Более конкретно, изобретение относится к способам согласования фазовых состояний гироскопических модулей на основе пространственно-интерференционного взаимодействия физических полей, что позволяет обеспечить коллективную ориентацию, устойчивое управление и согласованное движение в рое без централизованного управляющего устройства.
Настоящее изобретение может быть применено в беспилотной авиации, автономных подводных аппаратах, робототехнических системах, системах космической ориентации, мобильных распределённых сенсорных платформах, а также в перспективных навигационно-вычислительных комплексах, основанных на фазовом согласовании между отдельными физическими узлами. Способ может быть реализован как на основе оптических или акустических фазовых трактов, так и в электромагнитном ближнем поле, что обеспечивает широкую область применения при минимальной зависимости от внешней инфраструктуры.

A general theory of periodic diode laser arrays is developed in the approximation of an effective complex permittivity described by a step periodic function. Rigorous expressions are derived for the elements of a transfer matrix. Explicit expressions are obtained for the near-field and farfield patterns of a finite array. An analysis is made of the separate components of the radiation balance in an array and a two-dimensional optical-confinement factor is derived explicitly. A comparison of the results obtained with numerical calculations is made for a resonant antiguided structure.

PbS quantum dots of the average size 10 nm are synthesized in the polymer matrix (PVA) following chemical route. Optical absorption spectra reveal a large blue shift from the bulk absorption cutoff wavelength. Instead of using a high power laser, we have measured for the first time the third order nonlinear susceptibility (χ 3 ) of PbS quantum dots using a low power continuous wave laser with the Degenerate Four Wave Mixing (DFWM) technique. The result is encouraging in nonlinear optical application at room temperature.

To put the development of the X-ray laser in historic context this paper presents some of the motivation and history of the development of the X-ray laser fiom the perspective of a scientist at Lawrence Livermore National Laboratory where the k t X-ray laser was demonstrated in the early 1980's using a nuclear device as the driver.

We present a brief review of our progress towards measuring parity violation in heavy-metal chiral complexes using mid-infrared Ramsey interferometry. We discuss our progress addressing the main challenges, including the development of buffer-gas sources of slow, cold polyatomic molecules, and the frequency-stabilisation of quantum cascade lasers calibrated using primary frequency standards. We report investigations on achiral test species of which promising chiral derivatives have been synthesized.

We report on the measurements of nonlinear current-voltage characteristics of graphene fabricated by chemical vapor deposition. The current-voltage characteristic is described by a power law with a superlinear dependence of the current on the voltage, and the nonlinearity depends on the carrier density and the excitation level. The nonlinearity is strongest at the Dirac point and becomes weaker as the carrier density increases. At the Dirac point, we also observe a crossover to a much stronger nonlinear transport when the electric field increases above 10 4 V/m.

The two-dimensional barrier passage is studied in the framework of Langevin statistical reactive dynamics. The optimal incident angle for a particle diffusing in the dissipative non-orthogonal environment with various strengths of coupling between the two degrees of freedom is systematically calculated. The optimal diffusion path of the particle in a non-Ohmic damping system is revealed to have a probability to return to the potential valley under the combined influence of the off-diagonal system tensors.

In the course of in vitro studies of blood of laboratory animals with progressing Ehrlich carcinoma, we have revealed the change of the blood plasma optical properties in the THz range, which can be used for developing the express diagnostics of the presence of oncological diseases. An applied software package is elaborated that allows the phantoms of biological samples having a complex structure to be numerically simulated and the parameters of the electromagnetic wave reflected from these samples in the THz frequency range to be calculated.

Quantum dot cellular automata (QCA) introduces a pioneer technology in nano scale computer architectures. Employing this technology is one of the solutions to decrease the size of circuits and reduce power dissipation. In this paper, two new optimized FlipFlops with reset input are proposed in quantum dot cellular automata technology. In addition, comparison with related works is performed. The reset pin in the proposed circuits is level triggered. Simulation results demonstrate that both proposed desgins have efficient structures in terms of area, delay and complexity. The proposed structures are simulated using the QCA designer and validated. Simulations of the first proposed level triggered reset D-Flip Flop showed that this circuit has 82 quantum cells and required only two clock cycle for valid operation. In addition, the second proposed architecture for level triggered reset D-Flip Flop has only 85 quantum cells and it needs only one clock cycle for proper operation.

The behaviour of modern quartz glasses and êuorite is studied experimentally under a prolonged action of the 280-keV electron beam pulses and an overall êuence of up to $ 30 kJ cm À2 . The induced absorption in all investigated materials saturates with increasing the êuence. The maximum variation of transmission in high-purity CaF 2 samples does not exceed 5 % ë 10 % in the wavelength range 120 ë 1000 nm. Quasi-stationary absorption in the region of $ 180 ë 300 nm in the KS-4V quartz glass sample is approximately four times smaller than that in the KU-1 quartz glass and half the value for Corning 7980 glasses.

A composite of liquid crystal elastomer (LCE) incorporated with carbon nanotubes (CNTs) can convert absorbed photon energy into thermal energy to trigger the phase transition of the LCE, resulting in photo-thermo-mechanically actuated devices. We model the transient temperature distribution and the bending kinetics of a straight cantilever beam actuator under the radiation of a laser diode (LD) light. Three possible bending modes of the beam for various LD light powers are identified. The temperature distribution and the bending modes are found to be in good agreement with the reported experimental observations. The underlying deformation mechanisms and bending modes are manifested by probing the stress evolution and propagation of nonzero stress regions during the bending process. For a beam that is initially slightly curved, we also predict the possibility of snap-through instability, and three typical phases of snapping are captured. This procedure paves the way for the design of LCE-based soft actuators.