Interplay between topology and localization on superconducting circuits

Topological insulators occupy a prominent position in the realm of condensed matter physics. Nevertheless, the presence of strong disorder has the potential to disrupt the integrity of topological states, leading to the localization of all states.This study delves into the intricate interplay between topology and localization within the one-dimensional Su–Schrieffer–Heeger(SSH) model, which incorporates controllable off-diagonal quasi-periodic modulations on superconducting circuits.Through the application of external alternating current(ac) magnetic fluxes, each transmon undergoes controlled driving,enabling independent tuning of all coupling strengths. Within a framework of this model, we construct comprehensive phase diagrams delineating regions characterized by extended topologically nontrivial states, critical localization, and coexisting topological and critical localization phases. The paper also addresses the dynamics of qubit excitations, elucidating distinct quantum state transfers resulting from the intricate interplay between topology and localization. Additionally, we propose a method for detecting diverse quantum phases utilizing existing experimental setups.

Electromagnetic Performance Analysis of Variable Flux Memory Machines with Series-magnetic-circuit and Different Rotor Topologies

In this paper,the electromagnetic performance of variable flux memory(VFM)machines with series-magnetic-circuit is investigated and compared for different rotor topologies.Based on a V-type VFM machine,five topologies with different interior permanent magnet(IPM)arrangements are evolved and optimized under same constrains.Based on two-dimensional(2-D)finite element(FE)method,their electromagnetic performance at magnetization and demagnetization states is evaluated.It reveals that the iron bridge and rotor lamination region between constant PM(CPM)and variable PM(VPM)play an important role in torque density and flux regulation(FR)capabilities.Besides,the global efficiency can be improved in VFM machines by adjusting magnetization state(MS)under different operating conditions.

Overview of Circuit Topologies for Inductive Pulsed Power Supplies

The pulsed power supply(PPS)is one important component in the electromagnetic launch system.The inductive PPSs have attracted researchers’attentions with the major advantages of high energy storage density(over the capacitive PPSs)as well as simple structure and easy control(over the rotating mechanical PPSs).As for the inductive PPSs,the circuit topology of the basic module will directly determine the comprehensive performance of the whole system.From the perspectives of working principles,strengths,weaknesses,and comprehensive performance,this paper presents a historical and technical review of the major circuit topologies for the inductive PPSs.

Characterization of topological phase of superlattices in superconducting circuits

The recent experimental observation of topological magnon insulator states in a superconducting circuit chain marks a breakthrough for topological physics with qubits, in which a dimerized qubit chain has been realized. Here, we extend such a dimer lattice to superlattice with arbitrary number of qubits in each unit cell in superconducting circuits, which exhibits rich topological properties. Specifically, by considering a quadrimeric superlattice, we show that the topological invariant(winding number) can be effectively characterized by the dynamics of the single-excitation quantum state through time-dependent quantities. Moreover, we explore the appearance and detection of the topological protected edge states in such a multiband qubit system. Finally, we also demonstrate the stable Bloch-like-oscillation of multiple interface states induced by the interference of them. Our proposal can be readily realized in experiment and may pave the way towards the investigation of topological quantum phases and topologically protected quantum information processing.

Hard-core Hall tube in superconducting circuits

The Hall tube as a minimum model to simulate the integer quantum Hall effect is essential for exploring topological physics, while it has not been constructed in the recent developing successfully experiments on superconducting circuits.In this work, we propose a feasible experiment scheme using three legs superconducting circuits with transmon qubits to realize a Hall tube. Then we first investigate its topological properties. Since the time–reversal, particle–hole, and chiral symmetries are all broken for the system, the Hall tube belongs to the A class of the Altland–Zirnbauer classification.We obtain the corresponding topological phase transition both numerically and analytically. Since the chirality is a key character of the quantum Hall effect, we secondly investigate the chiral physics in the Hall tube. We find the topological protected chiral edge currents and discuss its robustness. Finally, we give the possible experimental observations of the topological state and topological protected chiral edge currents.

Optimization of a Si-SiO2 Waveguide Coupler for Photonic Integrated Circuits

In this paper, we demonstrated a compact Si-SiO2 waveguide coupler with a footprint of only 2 μm × 3 μm by topology optimization in the communication wavelength. The transmission was increased from 30% to 100%, much higher than other methods. Besides, the optimized structure did not incorporate other dielectric materials, facilitating fabrications and applications.

The Topological Conditions: The Properties of the Pair of Conjugate Tress

This paper presents some important properties emanating from the pair of conjugate trees. The properties are obtained by resorting to the fundamental loops and cutsets in the circuit topology. The existence of such a pair is one of the conditions for a nonlinear resistive circuit to have one and only one DC solution.

A Novel Integrated Circuit Driver for LED Lighting

A novel integrated circuit for driving LED lighting has been proposed, designed and fabricated. Besides the typical parts of LED driver, an integral part was added at the output terminal of error amplifier in the driver. In this way, a novel average current mode can be set up to take the place ordinary peak current control mode. In addition, a BUCK low-level topology was adopted, too. It can be used to drive up to eight 1 W HB LED lights with 350 mA constant current. In this way, the LED driver displays high performance, in which output current with less 1% error and total efficiency as high as 96%. The feasibility of the design has been verified by actual measurement on the fabricated chip.

Application of time-domain synthesis in constitution of breaking-capacity testing circuits

IntroductionThis paper presents a time-domain synthesis method for determiningthe topological structure and components parameters of breaking-capacity testing circuits according to transient recovery voltage (TRV) re-quirements specified by IEC standards.Composition of testing circuits,therefore,could rely on theoretical analysis,not mainly on physicalconcept and experience as before.Breaking-capaciiy testing is a dynami-cal process which should supply suitable breaking current related to ratedbreaking current and TRV complying with standard requirements,It hasgreat influence on synthesis of testing circuits,because the structure andcomponent parameters of circuits are determined not only by

中高压直流断路器的研究与应用

多端直流系统及直流电网是未来柔性直流输配电系统的发展方向,其安全可靠稳定运行需要有直流断路器作为保障。虽然国内外研究人员提出了各种直流断路器技术方案,但目前市场上能够满足实际工程应用的直流断路器产品仍十分缺乏。该文对直流断路器的研究工作进行了梳理。首先,分析了不同技术方案采取的换流方式及性能,并介绍了直流断路器中的核心组件及其驱动保护。其次,对各类型的直流断路器拓扑结构进行了总结,并归纳出改进优化的方向。最后,对直流断路器研制的关键技术与未来的发展趋势进行了讨论和总结,为中高压直流断路器研制与应用提供参考。

空间约束下电动汽车无线充电系统磁耦合结构优化

电动汽车无线充电系统在尺寸大小与位置偏移等因素的影响下,会导致系统传输能力下降。为了在空间约束条件下提升系统的输出功率、传输效率及抗偏移能力,针对位置偏移与底盘高度不同的实际情况,在经典D4线圈的基础上分别设计了收发端非对称D4和收发端非对称D4Q双层线圈磁耦合结构,以提高耦合系数和抗偏移能力。在不同方向的偏移和旋转的情况进行仿真测试,表明收发端非对称D4Q双层线圈在出现横向偏移300 mm、纵向偏移400 mm、传输距离230 mm和旋转偏移45°以内具备无线电能传输能力。通过搭建实验平台对偏移进行测试与验证,结果表明,所提出的收发端非对称D4Q磁耦合结构的最大输出功率相对于收发端对称D4磁耦合结构增加约60.34%,最大传输效率增大11%。

一种构建参数化量子线路的区块环拓扑结构

在变分量子算法中,参数化量子线路拓扑结构的选择对算法性能具有重要意义.目前已有的拓扑结构存在一些问题,如全连接拓扑结构所需量子门数量较多,环型拓扑结构的表达能力与纠缠能力略有欠缺.为了解决以上问题,本文提出了一种新型的区块环(Block-Ring,BR)拓扑结构,在保障良好性能的同时减少参数规模(即量子门数量),降低线路复杂度.在BR拓扑中,n个量子比特被等分为多个区块,每个区块包含m个量子比特,区块内部所有量子比特两两连接,区块之间采用环型结构进行连接.为了构造BR拓扑结构的参数化量子线路,设计了一种多层线路生成算法,可自动生成由单量子比特门Rx、Rz和双量子比特门CRx或CRz构成的量子线路.IBM Q模拟实验表明,相较于环型拓扑结构,无论单层、双层以及三层BR拓扑结构的表达能力和纠缠能力均有不同程度的提升;相较于拥有最高表达能力与纠缠能力的全连接拓扑结构,BR拓扑结构呈现接近的性能指标,且线路复杂度显著降低,即参数数量与双量子比特门数量均从O(n^(2))降低为O(mn),线路深度从O(n^(2))降低为O(n/m+m^(2)).

基于电流路径重构的无桥三电平PFC电路研究

文中提出一族电流路径重构的无桥三电平功率因数校正(power factor correction,PFC)电路,该族拓扑在无桥PFC的基础上,重构电流路径以减少电流路径中的功率器件,并保留无桥结构可靠性高和三电平结构器件应力低的优点。该族电路的任一工作模态仅需一个全控器件,有效降低全控器件损耗和电路控制复杂度。基于该族电路的工作原理分析,推导各器件应力、电压电流纹波与调制度的关系,利于元器件相关参数的设计,同时可推广到三电平电路拓扑的设计过程中;另外,设计该族电路调制技术及控制策略;最后,搭建实验样机,实验结果证明,该拓扑推衍方案的可行性和该族电路拓扑的有效性。

基于新能源发电改进型移相全桥变换器研究

新能源发电中需要广泛使用移相全桥变换器,以实现软开关技术从而减小系统的开关损耗。而传统移相全桥直流变换器滞后臂在轻载时难以实现ZVS,导致系统大功率输出时效率降低以及系统换路时容易产生尖峰电压、电流等现象,针对这一问题,提出了一种改进的有源软开关移相全桥DC-DC变换器拓扑。系统首先提出了改进变换器的拓扑结构,在此基础上对其工作模态进行了研究分析,并合理优化相关器件的选型,最后通过系统仿真及试验平台进行了系统仿真和试验测试,结果表明,所设计的加入辅助电路改进型移相全桥直流变换器在轻载情况下,能够使变换器滞后臂达到软开关效果,同时,在大功率输出情况下,对器件发热、电压波形振荡均有较好的抑制作用,系统整体效率变高,同时可靠性、稳定性变强。

考虑海缆实际载流量的海上风电集电系统拓扑优化

海缆实际载流量是海缆选型的重要依据,在海上风电场集电系统拓扑优化中,考虑不同敷设区段海缆载流量存在的差异以及海缆多回路并联敷设时磁热效应对载流量的影响,对保障集电系统的安全性具有重要意义。首先,采用模糊C均值算法对风机进行聚类分区,将集电系统拓扑优化分解为分区内、外拓扑优化。然后,在分区内采用基于Voronoi图的拓扑搜索算法进行求解;在分区外拓扑优化中,考虑海缆瓶颈区段、回路数对载流量的影响,构建混合整数非线性优化模型,线性化后采用优化求解器GUROBI进行求解。最后,以某实际风电场为例进行仿真验证。结果表明,所提模型能保证海缆实际载流量始终大于海缆工作电流,可有效保障集电系统的安全性。

磁阻型线圈发射器电路拓扑优化与性能提升

为提高线圈发射器的发射速度及能量利用率,研究了磁阻型电磁线圈发射器不同放电电路结构对发射性能的影响。对晶闸管式(SCR)、半桥式、阻容(RCD)吸收式、Boost-Buck式四种不同结构放电电路进行分析,使用有限元方法研究了四种电路对发射性能的影响。结果表明,相同条件下,相比SCR式电路,三种可关断电路中,Boost-Buck式电路下电枢出口速度提升最少,为78.77%;RCD式电路下系统能量利用率提升最少,为220.66%。可关断电路中电流的衰减速率会影响电枢的加速度,存在最优电流衰减速率曲线;单级可关断电路中出口速度与系统能量利用率搭配最均衡的为半桥式放电电路;Boost-Buck式放电电路更具灵活性,更适合应用于多级线圈发射器中。

基于电容吸收拓扑电路的新型磁阻线圈发射器

磁阻线圈发射器具有出口速度一致性好、可靠性高和能源清洁等优点。但是现有磁阻线圈发射器普遍效率较低,限制了其工程应用。为提高发射效率,提出一种基于电容吸收拓扑电路的新型磁阻线圈发射器方案。首先建立了传统二级磁阻式发射器的模型,采用有限元软件进行了仿真计算。结果显示,在电枢经过线圈中心后,驱动线圈中剩余电流产生的磁场会使电枢受到反向电枢拖拽力而减速。针对上述问题,提出一种新型的基于电容吸收拓扑电路的能量回收方案,分析了各阶段的放电特性。计算结果表明:与传统放电电路相比,新型放电电路可以使驱动线圈的剩余电流被电容器吸收实现快速衰减,电枢出口速度由21.46 m/s提高至26.19 m/s,效率由14.50%提高至21.59%。新型放电电路能够对电枢加速后的剩余能量进行回收,明显减小电枢拖拽力,提高了发射速度与能量回收效率。

NISQ设备的量子电路调度策略优化研究

在嘈杂的中尺度量子(noisy intermediate-scale quantum,NISQ)时代,调度是量子电路编译的关键步骤。传统调度策略未充分利用量子计算的并行性,忽略了层内操作的潜在并行优化。因此,设计了两种优化策略:拓扑层级调度策略(topological layered scheduling strategy,TLSS)和层内冲突优化策略(layerwise conflict optimization strategy,LCOS)。TLSS利用贪心算法和拓扑排序原理,在层结构中分配量子门,以最大化并行执行量子门操作的数量。LCOS在层内插入SWAP门并最小化冲突以提高并行度,优化整体计算效率。实验结果表明,在涉及4至22量子比特、平面拓扑结构以及双量子比特的平均寿命为67μs的特定环境下,TLSS与LCOS分别降低51.1%和53.2%的SWAP门数量,减少14.7%和15%的硬件门开销。由于量子电路的复杂性及层间时序关系的干扰,将两策略结合后SWAP门数量降低51.6%,硬件门开销减少14.8%。然而结果的适用性受到不同结构和硬件限制的影响。

海水对UUV WPT系统的影响及耦合机构的补偿研究

针对水下无人航行器(UUV)无线电能传输(WPT)系统的效率和稳定性问题,建立了水下WPT等效电路,并对其工作原理进行了数学推导和分析。以此为基础研究了海水环境对WPT电路性能的影响机理,推导出了WPT系统在海水中的传输功率及效率模型。由于在海浪和海流等水下外界干扰下电能传输机构的收/发端均会产生偏移,从而影响系统电能传输的稳定性和效率。为减小影响,分析了4种典型拓扑补偿电路结构,并给出了最优补偿电路选取原则。最后,在MATLAB平台进行验证,结果验证了数学推导的正确性以及补偿电路设计的有效性。研究结果可为类似水下无线供电系统的设计提供借鉴。

一种具有限流功能的电容型高压直流断路器

直流断路器作为直流电网实现故障清除的重要设备之一,其性能的优劣将直接影响系统的安全稳定运行。针对目前大部分断路器不具备故障限流能力且成本较高这一问题,提出了一种具有限流功能的电容型高压直流断路器设计方案。利用电容的充放电特性实现限流电抗和避雷器的投切,能够显著降低故障电流峰值;将传统直流断路器中大规模全控器件IGBT(绝缘栅双极晶体管)用电容来替代,在实现断流功能的同时有效降低了成本。基于PSCAD/EMTDC仿真软件搭建单端等效模型并进行仿真验证,结果表明:相较于传统高压直流断路器,所提方案降低了故障电流峰值,缩短了故障隔离时间,具有较好的性能。