How to Achieve Perfect Simulation and a Complete Problem for Non-interactive Perfect Zero-Knowledge

This paper studies perfect zero-knowledge proofs. Such proofs do not allow any simulation errors, and therefore techniques from the study of statistical zero-knowledge (where a small error is allowed) do not apply to them. We introduce a new error shifting technique for building perfect simulators. Using this technique we give the first complete problem for the class of problems admitting non-interactive perfect zero-knowledge (NIPZK) proofs, a hard problem for the class of problems admitting public-coin PZK proofs, and other applications.     

Permittivity spectra and characteristic energy losses of electrons in ZnO at 100 K

For the first time, full sets of fundamental optical functions have been obtained for zinc oxide in the range 0–30 eV at 100 K for E ⊥ c and E ‖ c polarizations. Spectra of the transverse and longitudinal components of transitions and their basic parameters (peak energies E _i , half-widths H _i of transition bands, band areas S _i , and oscillator strengths f _i ) have also been determined for the first time. The calculations are performed using synchrotron experimental reflectance spectra. The main features of spectra of the optical functions and components of transitions are established. These features are compared to the results of known theoretical calculations of the bands and spectra of optical functions.     

Fundamental spectra of optical functions of ferroelectric sodium nitrite

Spectra of optical fundamental functions of ferroelectric sodium nitrite were determined in the range 4–24 eV at 77 K for the three polarizations: E ∥ a, E ∥ b, and E ∥ c. The calculations were based on the experimental R(E) reflection spectra and integral Kramers-Kronig relations. Using the method of Argand diagrams, the permittivity and bulk characteristic electron loss spectra were decomposed into the elementary transverse and longitudinal components. Their main parameters were determined. The obtained data were compared with the theoretical calculations of the permittivity spectra performed using the FPLAPW method. The main features of the permittivity spectra, the parameters of the transitions, and their theoretical nature were established.     

A Hybrid Fault-Tolerant Architecture for Highly Reliable Processing Cores

Increasing vulnerability of transistors and interconnects due to scaling is continuously challenging the reliability of future microprocessors. Lifetime reliability is gaining attention over performance as a design factor even for lower-end commodity applications. In this work we present a low-power hybrid fault tolerant architecture for reliability improvement of pipelined microprocessors by protecting their combinational logic parts. The architecture can handle a broad spectrum of faults with little impact on performance by combining different types of redundancies. Moreover, it addresses the problem of error propagation in nonlinear pipelines and error detection in pipeline stages with memory interfaces. Our case-study implementation of a fault tolerant MIPS microprocessor highlights four main advantages of the proposed solution. It offers (i) 11.6 % power saving, (ii) improved transient error detection capability, (iii) lifetime reliability improvement, and (iv) more effective fault accumulation effect handling, in comparison with TMR architectures. We also present a gate-level fault-injection framework that offers high fidelity to model physical defects and transient faults.     

Reflection spectra of two polymorphic modifications of cadmium arsenide

The optical properties of cadmium arsenide are studied. Reliable new data on the reflection spectra are obtained owing to the use of perfect crystals and high-precision spectral equipment. The reflection spectra of the polymorphic modifications α″-Cd₃As₂ (space group D _4h ¹⁵ ) and α′-Cd₃As₂ (space group ) are D _4h ¹¹ are recorded at room and liquid-nitrogen temperatures in polarized light (E ⊥ c, E ‖ c) at incident-light photon energies of 1–5 eV. For the α′ modification, anisotropy is observed in the reflection spectra for the first time. The obtained results are compared with the known experimental and theoretical data.     

Demonstration of a Dual-Band Mid-Wavelength HgCdTe Detector Operating at Room Temperature

In this paper, the performance of sequential dual-band mid-wavelength N⁺-n-p-p-P⁺-p-p-n-n⁺ back-to-back HgCdTe photodiode grown by metal-organic chemical vapor deposition (MOCVD) operating at room temperature is presented. The details of the MOCVD growth procedure are given. The influence of p-type separating-barrier layer on dark current, photocurrent and response time was analyzed. Detectivity without immersion D^* higher than 1 × 10⁸ cmHz^1/2/W was estimated for λ_Peak = 3.2 μm and 4.2 μm, respectively. A response time of τ_s ～ 1 ns could be reached in both MW1 and MW2 ranges for the optimal P⁺ barrier Cd composition at the range 0.38–0.42, and extra series resistance related to the processing R_Series equal to 500 Ω.     

Fine Structure of the long-wavelength edge of exciton-phonon absorption and hyperbolic excitons in silicon carbide of 6<Emphasis Type="Italic">H</Emphasis> polytype

The fine structure of the long-wavelength edge of the polarization spectra of exciton-phonon absorption in moderate-purity n-type 6H-SiC crystals with a concentration of uncompensated donors N_D?N_A=(1.7–2.0)×10¹⁶ cm^?3 at T=1.7 K was studied. The analysis of new special features found at the absorption edge and the reliable detection of the onset of exciton-phonon steps related to the emission of phonons from acoustical and optical branches allowed highly accurate determination of a number of important parameters such as the band gap, the exciton band gap, the exciton binding energy, and the energies of spin-orbit and crystal-field splitting of an exciton. For the first time, transitions with the emission of LA phonons to the 1S exciton state with an M₁-type dispersion law were detected in E ∥ Z(C) polarization (the electric-field vector is parallel to the optical axis of the crystal). This observation supports the previously predicted “two-well” structure of the conduction band minimum in 6H-SiC.     

Electron-phonon damping factor for the landau quantization of 2D electrons with a fine structure of the energy spectrum

The drift of degenerate 2D electrons in the channel of the heterojunction potential well is considered. In a quantizing magnetic field B, the electrons scan the defects of the heteroboundary, which perturb their momentum and energy equilibrium state (T, T _D ⁰ ). The stationary nonequilibrium state (T, T _D ^* ) is attained by electron-phonon relaxation in energy and momentum. The experimentally observed nonlinear dependence T_D(T) is explained by the admixture of deformation acoustic phonons to the interaction of 2D electrons with piezoelectric phonons.     

Valence-band offsets in strained SiGeSn/Si layers with different tin contents

Admittance spectroscopy is used to study hole states in Si_0.7–y Ge_0.3Sn _y /Si quantum wells in the tin content range y = 0.04–0.1. It is found that the hole binding energy increases with tin content. The hole size-quantization energies in structures containing a pseudomorphic Si_0.7–y Ge_0.3Sn _y layer in the Si matrix are determined using the 6-band kp method. The valence-band offset at the Si_0.7–y Ge_0.3Sn _y heterointerface is determined by combining the numerical calculation results and experimental data. It is found that the dependence of the experimental values of the valence-band offsets between pseudomorphic Si_0.7–y Ge_0.3Sn _y layers and Si on the tin content is described by the expression ΔE _V ^exp = (0.21 ± 0.01) + (3.35 ± 7.8 × 10^–4)y eV.     

Effect of the reflection coefficients on the conductivity of a thin metal layer in the case of an inhomogeneous time-periodic electric field

In the case of an inhomogeneous time-periodic electric field E, the electrical current distribution is evaluated for a thin metal layer with different reflection coefficients q₁ and q₂ of its surfaces. The dependence of the conductive function Σ on the frequency of the external inhomogeneous time-periodic electric field and on the coefficient of the inhomogeneous field κ is analyzed. The relaxation time approximation to the kinetic Boltzmann equation for electron transport is used.     

Analysis of a high frequency and wide bandwidth active polyphase filter based on CMOS inverters

An active polyphase filter capable of high frequency quadrature signal generation has been analyzed. The resistors of the classical passive polyphase filter have been replaced by transconductors, CMOS inverters (F. Tillman and H. Sjöland, Proceedings of the Norchip Conference (pp. 12–15), Nov. 2005; Analog Integrated Circuits and Signal Processing, 50(1) 7–12, 2007). A three-stage 0.13 μm CMOS active polyphase filter has been designed. Simulations with a differential input signal show a quadrature error less than 1° for the full stable input voltage range for frequencies from 6 GHz to 14 GHz. Phase errors in the differential input signal are suppressed at least three times at the output. Corner simulations at 10 GHz show a maximum phase error of 3° with both n- and pMOS slow, in all other cases the error is less than 0.75°. The three-stage filter consumes 34 mA from a 1.2 V supply. To investigate the robustness of the filter to changes in inverter delay, an inverter model was implemented in Verilog-A. Linear c _in and g _in were used, whereas g _m , c _out , and g _out were non-linear. It was found that the filter could tolerate substantial delays. Up to 40° phase shift resulted in less than 1.5° quadrature phase error at the output.     

Nonohmic conductivity under transition from weak to strong localization in GaAs/InGaAs structures with a two-dimensional electron gas

Dependences of electrical conductivity σ on temperature and electric-field strength were studied in a wide range of conductivities (from σ ? e²/? to σ ? e²/?) in GaAs/InGaAs/GaAs structures with a two-dimensional electron gas. It is shown that one cannot reliably determine the mechanism of conductivity from the temperature dependence of ohmic conductivity. Studies of nonohmic conductivity make it possible to determine the range of values of low-temperature conductivity that correspond to the transition from the diffusion mechanism of conductivity to the hopping mechanism. It is shown that, in the structures under investigation, the conductivity is still controlled by diffusion as the degree of disorder increases even when the low-temperature conductivity is much lower than e²/?.     

Topological Insulator Superlattices

HgTe/CdTe and InAs/GaSb/AlSb superlattices both exhibit a topological insulator transition. In each case, there is an inversion of the s- and p-band ordering for layer thicknesses above a critical value. The resulting topological phase is a 2D bulk insulator at zero temperature, with edges that conduct massless carriers whose direction of motion is locked to their direction of spin. These 1D edge states exhibit essentially dissipationless transport over coherence lengths greater than one micron, with a quantized conductance of e²/h per edge. When a current passes, opposite spins are separated to the two sample edges, giving rise to the so-called quantum spin Hall effect. Effects such as these may be exploited in future low temperature spintronic devices. The edge states in HgTe/CdTe differ from those in InAs/GaSb/AlSb in several ways, due to the type II band alignment and weaker electron–hole hybridization of the III-V superlattice. The former exhibit a simple exponential decay over thousands of Angstroms, while the latter are more strongly confined to the edge, with an oscillating wave function whose period increases with the edge state momentum. In any calculation, the edge state dispersion and the nature of the wave-function depend strongly on the boundary conditions used. A k · p model is presented using standard boundary conditions for the wave function and its derivative, which yields spin polarized edge states with a finite amplitude at the sample edge. The interaction between states at opposite sample edges is also considered.     

The band structure and the double metal-insulator-metal phase transition in the conductivity of elastically strained zero-gap Cd<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Hg<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Te

In the zero-gap Cd _x Hg_1?x Te semiconductor subjected to an axial elastic strain, a band gap is formed between the bottom of the conduction band and the top of the valence band. In the new state, the band structure is found to depend on the initial arrangement of the valence subbands, i.e., on the composition defined by the parameter x. At x < 0.135–0.140, the material becomes a semiconductor with an indirect band gap. If 0.140 < x < 160, the band of light holes at k = 0, Γ₆, is found to be above the Γ₈ band. As a result, the material becomes a direct-gap semiconductor, and a double “metal-semiconductor-metal” phase transition in conductivity occurs. In this case, as the strain is increased, the type of conductivity of the zero-gap semiconductor at low temperatures changes according to the sequence as follows: electron metallic conductivity-electron activation conductivity-hopping conductivity-hole metallic conductivity.     

A Faddeev Systolic Array for EKF-SLAM and its Arithmetic Data Representation Impact on FPGA

The Extended Kalman Filter (EKF) computation is a core task for the simultaneous localization and mapping (SLAM) problem in autonomous mobile robots. The SLAM problem involves operations over high dimension data sets, requiring high throughput and performance, given the real-time nature of the robotics, control-decision algorithm this task is a part of. The lightweight and power restricted computing environments in mobile robotics requires customized processing systems such as Field-Programmable Gate Arrays (FPGAs). This work presents an arithmetic precision analysis and a Faddeev algorithm to calculate the Schur’s Complement hardware architecture implementation for the EKF-SLAM using a Systolic Array (SA). While it is widely believed that fixed-point implementations of arithmetic operations lead to area and performance benefits on FPGAs, the results in this article reveal that each Processing Element (PE) in the SA consumes 25% more logic and about 30% more register resources for the fixed-point 13.23 representation than if using the IEEE-754 single precision floating-point format. In addition, for FPGA devices with hardware support for key components of floating-point computations, a single PE floating-point implementation can achieve a maximum frequency up to 50% higher than a corresponding fixed-point implementation for the same relative numeric errors.     

Computation-skip Error Mitigation Scheme for Power Supply Voltage Scaling in Recursive Applications

Aggressive power supply voltage V_dd scaling is widely utilized to exploit the design margin introduced by the process, voltage and environment variations. However, scaling beyond the critical V_dd results to numerous setup timing errors, and hence to an unacceptable output quality. In this paper, we propose computation-skip (CS) scheme to mitigate setup timing errors, for recursive digital signal processors with a fixed cycles per instruction (CPI). A coordinate rotation digital computer (CORDIC) with the proposed CS scheme still functions when scaling beyond the error-free voltage. It enables better-than-worst-case design constraint and achieves 1.82 X energy saving w.r.t. nominal V_dd condition, another 1.49 X energy saving without quality degradation, and another 1.09 X energy saving when sacrificing 8.35 dB output quality.     

Current oscillations under lateral transport in GaAs/InGaAs quantum well heterostructures

The current-voltage (I–V) characteristics were measured and the current-pulse oscilloscope patterns were obtained for multilayer n-InGaAs/GaAs quantum-well heterostructures and n-GaAs epitaxial layers with various doping levels. It is shown that the I–Vcharacteristics flatten at low doping levels in fields of 300–400 V/cm. In more heavily doped samples, current oscillations are initiated with a period corresponding to a drift velocity of (3–3.5)×10⁵ cm/s at E ‖ [110] and are approximately larger at E ‖ [100] by a factor of 1.5. The results obtained are attributed to the formation of, respectively, stationary and moving acoustoelectric domains in the structures. In fields above 1.5 kV/cm, high-frequency Gunn oscillations corresponding to a drift velocity of 1.5 × 10⁷ cm/s were observed.     

Computationally Efficient Motion Estimation Algorithm for HEVC

In this paper, we present a novel computationally efficient motion estimation (ME) algorithm for high-efficiency video coding (HEVC). The proposed algorithm searches in the hexagonal pattern with a fixed number of search points at each grid. It utilizes the correlation between contiguous pixels within the frame. In order to reduce the computational complexity, the proposed algorithm utilizes pixel truncation, adaptive search range, sub-sampling and avoids some of the asymmetrical prediction unit techniques. Simulation results are obtained by using the reference software HM (e n c o d e r_l o w d e l a y_P_m a i n and e n c o d e r_r a n d o m a c c e s s_m a i n profile) and shows 55.49% improvement on search points with approximately the same PSNR and around 1% increment in bit rate as compared to the Test Zonal Search (TZS) ME algorithm. By utilizing the proposed algorithm, the BD-PSNR loss for the video sequences like B a s k e t b a l l P a s s_416 × 240@50 and J o h n n y_1280 × 720@60 is 0.0804 dB and 0.0392 dB respectively as compared to the HM reference software with the e n c o d e r_l o w d e l a y_P_m a i n profile.     

Magnetic susceptibility of Bi<Subscript>2</Subscript>Te<Subscript>3</Subscript>-Sb<Subscript>2</Subscript>Te<Subscript>3</Subscript> alloys

The magnetic susceptibility of Czochralski-grown single crystals of Bi₂Te₃-Sb₂Te₃ alloys containing 0, 10, 25, 40, 50, 60, 65, 70, 80, 90, 99.5, or 100 mol % Sb₂Te₃ has been investigated. The magnetic susceptibility of these crystals was determined at the temperature T = 291 K and the magnetic field H oriented parallel (χ_‖) and perpendicularly (χ_⊥) to the trigonal crystallographic axis C ₃. A complicated concentration dependence of the anisotropy of magnetic susceptibility χ_‖/χ_⊥ has been revealed. The crystals with the free carrier concentration p ≈ 5 × 10¹⁹ cm^?3 do not exhibit anisotropy of magnetic susceptibility. The transition to the isotropic magnetic state occurs for the compositions characterized by a significantly increased (from 200 to 300 meV) optical bandgap.     

The following the perturbed leader algorithm and its application for constructing game strategies

A modification of Hannan’s Following the Perturbed Leaded (FPL) algorithm for the case of unlimited gains and losses is considered. Estimates of the prediction error are obtained in terms of the volume v _t and game fluctuation fluc(t) = Δv _t /v _t , where Δv _t = v _t –v _t–1. We prove the asymptotic consistency on the average of this variant of the algorithm for fluc(t) = o(t). Applications of this algorithm for constructing game strategies are considered. Game strategies employing the difference between the “micro” and “macro” volatility of the discrete time series (prices of the financial instrument) are determined for obtaining arbitrage. Mixing these expert strategies is performed on the basis of the variant of Hannan’s algorithm developed in this work.