Effects of Dissipations on Fluctuations in an RLC Circuit with a Source in a Thermal Bath

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Multiple time scale chaos in a Schmitt trigger circuit

It is known that stray radio frequency signals can produce nonlinear effects that disrupt the operation of circuits, but the mechanisms by which this disruption occurs are not well known. In this paper, an emitter coupled Schmitt trigger circuit is driven with a high-frequency signal to look for disruptive effects. As the circuit makes a transition between mode locked states (period 2 and period 3, for example), there is a region of chaos in which the largest peak in the power spectrum is in between the mode-locked frequencies, and is not related to the driving frequency by an integer multiple. This chaos resembles the chaos seen during a period adding sequence, except that it contains frequencies ranging over many orders of magnitude, from the driving frequencies on the order of megahertz, down to a few hertz. It is found that only a one-transistor circuit is necessary to produce this extremely broadband chaos, and true quasiperiodicity is not seen in this circuit. The single-transistor circuit is then simulated to confirm the frequency conversion effects.     

Mode selection in a neuron driven by Josephson junction current in presence of magnetic field

Josephson junction is an active electric component and its channel current can be adjusted by external magnetic field, which can trigger additive phase error along the junction. From physical viewpoint, the Josephson junction can capture and release field energy when it is exposed to a magnetic field, and this time-varying current can be used to excite neural circuit for generating target firing patterns. In this paper, a Josephson junction is connected to a simple neural circuit, which is made of a capacitor, induction coil, a nonlinear resistor, two linear resistors and one constant voltage source in the branch, and the improved neural circuit is adjusted to percept external magnetic field and estimate the potential application of Josephson junction in nonlinear circuits. Bifurcation analysis is applied to explore the mode selection and dynamics dependence on parameters setting in the biophysical neural circuits. Furthermore, the neural circuit is exposed to external magnetic field and its physical effect is estimated by applying scale transformation on the variables and parameters in the neural circuit. It is confirmed that the neural circuit can be controlled and the neural activity shows distinct mode transition by taming the intensity (or angular frequency in periodic field) of external magnetic field. This kind of neural circuit can be further used as smart sensor for detecting weak magnetic field.     

Quantum state measurement in double quantum dots with a radio-frequency quantum point contact

We study the dynamics of two electron spins in coupled quantum dots （CQDs） monitored by a quantum point contact （QPC） detector. Their quantum state can be measured by embedding the QPC in an LC circuit. We derive the Bloch-type rate equations of the reduced density matrix for CQDs. Special attention is paid to the numerical results for the weak measurement condintion under a strong Coulomb interaction. It is shown that the evolution of QPC current always follows that of electron occupation in the right dot. In addition, we find that the output voltage of the circuit can reflect the evolution of QPC current when the circuit and QPC are approximately equal in frequency. In particular, the wave shape of the output voltage can be improved by adjusting the circuit resonance frequency and bandwidth.     

Pancharatnam Phase of a Mesoscopic Coupled Circuit

We derive a formula of the nonadiabatic noncyclic Pancharatnam phase for a mesoscopic circuit with coupled inductors and capacitors. It shows that, because of coupling effect, the circuit is in squeezed quantum state initially, and the time evolution of Pancharatnam phase exhibits an oscillation in a complex way. Especially we find that when the capacity of the coupled capacitors is larger than that of other ones in the circuit, with the variation of time Pancharatnam phase becomes nearly periodic square-wave, which perhaps can provide a new approach for the realization of quantum logic gate.     

Pancharatnam Phase of a Mesoscopic Coupled Circuit

We derive a formula of the nonadiabatic noncyclic Pancharatnam phase for a mesoscopic circuit with coupled inductors and capacitors. It shows that, because of coupling effect, the circuit is in squeezed quantum state initially, and the time evolution of Pancharatnam phase exhibits an oscillation in a complex way. Especially we find that when the capacity of the coupled capacitors is larger than that of other ones in the circuit, with the variation of time Pancharatnam phase becomes nearly periodic square-wave, which perhaps can provide a new approach for the realization of quantum logic gate.     

How to utilize a Grover search in general programming

It is widely believed that quantum computers (if realized) will be more powerful than today’s computers from the viewpoint of computational complexity. However, it is not obvious how to utilize quantum computers in practical situations. For practical purposes, a Grover search may be one of the most promising quantum algorithms known so far. Thus, in this paper, we propose an efficient framework where we can use Grover search for general programming. Our framework has the following steps. (1) A programmer writes a program by using standard C++ programming language. (2) Some if expressions within for loops in the C++ source code are chosen as candidates to be performed as a Grover search on a quantum computer. (3) The framework automatically generates a corresponding quantum circuit for each Grover search chosen in (2). Unlike the existing quantum circuit design methods, we can treat large problems in our quantum circuit design. (4) By evaluating the number of primitive quantum gates in the quantum circuit generated in (3), the framework determines whether the processing time of the quantum circuit is faster than the processing time of the corresponding if expression on a classical computer. If the framework determines that the quantum circuit is faster, it generates some interface source codes for a classical computer. Thus, in our framework, a programmer can use a Grover search with almost no effort.     

Analysis of a Novel Ka-band Folded Waveguide Amplifier for Traveling-Wave Tubes

A novel Ka-band folded waveguide （FW） amplifier for traveling wave tubes （TWT） is investigated. The dispersion curve and interaction impedance are obtained and compared to the normal FW circuit by numerical simulation. The interaction impedance is higher than a normal circuit through the whole band. We also study the beamwave interaction in this novel circuit, and the nonlinear large-signal performance is analyzed by a 3-D particlein-cell code MAGIC3D. A much higher continuous-wave （CW） output power with a considerably shorter circuit compared to a normal circuit is predicted by our simulation. Moreover, the novel FW even has a broader 3-dB bandwidth. It therefore will be useful in designing a miniature but high-power and broadband millimeter-wave TWT.     

一种快速有效的NQR探头恢复方法

介绍了一种用于主动减小NQR探头恢复时间的Q值变换电路,它利用MOEFET控制变Q电路与探头电路的耦合,并通过变压器增加与电感线圈串联的阻抗值以达到改变Q值的目的. 此电路不会产生新的振铃也不会对接收NQR的分辨率造成损失. 实验结果表明,电路能有效缩短探头的恢复时间,同时还可以提高信噪比.     

Quantum Fourier Transform-Based Arithmetic Logic Unit on a Quantum Processor

This study proposes and construct a primitive quantum arithmetic logic unit (qALU) based on the quantum Fourier transform (QFT). The qALU is capable of performing arithmetic ADD (addition) and logic NAND gate operations. It designs a scalable quantum circuit and presents the circuits for driving ADD and NAND operations on two-input and four-input quantum channels, respectively. By comparing the required number of quantum gates for serial and parallel architectures in executing arithmetic addition, it evaluates the performance. It also execute the proposed quantum Fourier transform-based qALU design on real quantum processor hardware provided by IBM. The results demonstrate that the proposed circuit can perform arithmetic and logic operations with a high success rate. Furthermore, it discusses in detail the potential implementations of the qALU circuit in the field of computer science, highlighting the possibility of constructing a soft-core processor on a quantum processing unit.     

Quantum mechanical effects of a nondissipative mesoscopic capacitance coupling circuit with source

The charge and current quantum zero-point fluctuations in a squeezed vacuum state of a nondissipative mesoscopic capacitance coupling circuit with source are given. The quantum noise of this circuit at absolute zero temperature is derived. It is found that there is a squeezing effect in this coupling circuit.     

Dynamical behavior of a mesoscopic circuit in phonons bath derived by virtue of the IWOP technique

Taking into account the interactions between electrons and phonons, we study the dynamic behavior of a dissipative mesoscopic circuit for pure initial coherent state of phonon bath modes by virtue of the IWOP technique. It shows that if the bath modes are initially in coherent states, some phenomena like Brownian behavior will appear in mean charge and current of the mesoscopic circuit. The quantum fluctuations of charge and current are constant and irrelevant to the coupled coefficients between electrons and phonons.     

The Current-Voltage Characteristics and Potential Oscillations of a Double Layer in a Triple-Plasma Device

The properties of a strong double layer in a current circuit with a capacitance and an inductance are investigated in a triple-plasma device. The double layer gives rise to a region of negative differential resistance in the current-voltage characteristic of the device, and this gives nonlinear oscillations in the current and the potential drop over the double layer (?DL). For a sufficiently large circuit inductance ?DL reaches an amplitude given by the induced voltage (-Ldl/dt) which is much larger than the circuit EMF due to the rapid current decrease when ?DL increases. A variable potential minimum exists in the plasma on the low-potential side of the double layer, and the depth of the minimum increases when ?DLFDL increases. An increasing fraction of the electrons incident at the double layer are then reflected, and this is found to be the main process giving rise to the negative differential resistance. A qualitative model for the variation of the minimum potential with ?DL is also proposed. It is based on the condition that the minimum potential must adjust itself self-consistently so that quasi-neutrality is maintained in the plasma region where the minimum is assumed.     

Analysis of the effect of stray capacitance on a charge/discharge-based electrical capacitance tomography system

The measurement circuit of electrical capacitance tomography (ECT) system mainly includes CMOS switches, C/V conversion circuit and Data processing circuit. In order to improve the image reconstruction quality, conversion circuit is very necessary to the small capacitance measurement circuit. A charge/discharge measurement circuit is one of the most suitable for the C/V conversion circuit in ECT. The stray capacitance between the measurement electrodes and earth can be large and have an effect on the capacitance measurement. This paper analyzes this effect, taking into account the ON-resistance of the COMS switch, the unit gain frequency of op-amp, and gain error in the measurement circuit. Finally, it is shown that if the range of stray capacitance is 150 ± 60 pF, overall error would be estimated. Comparing the effects of the circuit parameters, this charge/discharge-based capacitance is effectively stray-immune. It is a more efficient analysis to C/V circuit in ECT and offers a great benefit to information processing.     

The Necessary and Sufficient Conditions for a Universal Conservation of a State of a Unitary Quantum Circuit

By A. Peres and A. Stern's opinions a computational process evolves along a cyclic logic orbit defined by the sequence ψ₀→ψ₁→ … →ψ_M-1→ψ₀. It begins from a start position and returns to the same position after a computation. A. Stern thought that if we could design such a circuit, its operations can be extended to including nonconservative behavior associated with the external perturbations or internal quantum errors. A. Peres did not discuss how to make φ_M-1=φ₀. A. Stern proposed only a necessary condition for a conservation of a state of a quantum circuit. In this paper we present a necessary and sufficient condition for a universal conservation of a state of a quantum circuit. We also find all operators which can allow the conservation.     

Formation and focusing of electron beams in an electron-optical system with a plasma emitter placed in a magnetic field

The configuration and strength of a magnetic field are calculated in the regions of electron generation, acceleration, and transport in the electron-optical system of the plasma electron source. A magnetic field necessary for discharge initiation and maintenance is generated with a permanent magnet placed in a discharge chamber. It is shown that the magnetic field strength and configuration in these regions can be considerably varied by appropriately choosing the materials of electrodes forming the magnetic circuit. It is found that the beam focusing can be significantly improved by producing a quasi-uniform magnetic field in the electron-optical system of the plasma electron source.     

Mathematical modeling of random coupling between polarization modes in single-mode optical fibers: VII. Zero drift in a fiber ring interferometer with a circuit formed by a twisted optical fiber with weak natural linear birefringence

Zero drift and fading of the interference signal determined by polarization nonreciprocity at the exit from a fiber ring interferometer (FRI) of great length designed for recording a number of general relativity (GR) effects and made on the basis of a uniformly twisted single-mode optical fiber (SMF) with weak natural birefringence are considered. The calculations are carried out by numerical simulation using the model of random coupling between orthogonal polarization modes in an SMF, which was proposed in the first part of this work. The so-called minimum arrangement of an FRI with a nonmonochromatic radiation source, including a linear polarizer located between two beam splitters, is considered. Numerical estimates are made. It is shown that the FRI with a circuit on the basis of a twisted SMF has a significantly smaller zero drift and significantly smaller fading of the interference signal than the FRI with a circuit formed by an untwisted SMF. It is shown that the FRI produced on the basis of a twisted SMF provides the polarization sensitivity necessary for detecting the GR effects under study.     

Timing extraction in optical transmissions

The variance of the jitter in a timing recovery circuit for fibre optical digital transmission is computed. The timing circuit is simply a narrow-band filter, tuned to the pulse repetition frequency. It is found that, if the time dispersion of the fibre is limited, this circuit provides satisfactory timing information.     

Stability of a vacuum arc discharge on surfaces of hot-rolled steels and its frequency characteristics

The stability of a vacuum arc discharge (VAD) with allowance made for the parameters of an external circuit and a deduced equation of the heterogeneous kinetics of elementary cathode spots (ECSs) in the group cathode spot with one-dimensional configuration is analyzed. It is theoretically and experimentally shown that a VAD with a rising voltage-current characteristic (VCC) is stable independently of the parameters of the external circuit. Stability conditions for a VAD with falling VCC are found.     

无线电引信双源辐照效应研究

为了探索复杂电磁环境对无线电引信的作用规律,提出双辐射源电磁环境构建方法和试验方法,试验研究了无线电引信的双辐射源电磁环境效应,找到了使无线电引信意外起爆的双辐射源辐照频率组合方式和敏感阈值。发现双辐射源使无线电引信意外起爆的作用机理:引信天线及弹体接收到差频为多普勒频率的复合连续波信号,经自差机振荡器混频、检波管检波并滤波后,输出信号幅度较大的正弦波信号,经低频电路放大、信号整流积分及抗干扰惯性支路的共同作用,通过增幅速率选择电路,触发执行级电路误动作导致引信意外起爆。