航天相机热实验测试系统设计

为了检测航天相机在高低温环境中的电子学性能及可靠性,针对某型号航天相机地面热实验测试需求,设计开发出了一种热实验测试系统,详细介绍了系统的软硬件设计方案及控温策略。系统使用人机交互界面实现热控策略,能实时完成最高80个测试点(160个温度传感器及80路加热器)的控温任务,可以在－30℃～＋50℃范围内对航天相机进行全方位的温度监控,最高控温精度达到0.5℃。经过实际测试验证,系统具有很好的稳定性,能满足航天相机地面热实验的测试需求,工程应用价值高。     

Measuring Loschmidt echo via Floquet engineering in superconducting circuits

The Loschmidt echo is a useful diagnostic for the perfection of quantum time-reversal process and the sensitivity of quantum evolution to small perturbations. The main challenge for measuring the Loschmidt echo is the time reversal of a quantum evolution. In this work, we demonstrate the measurement of the Loschmidt echo in a superconducting 10-qubit system using Floquet engineering and discuss the imperfection of an initial Bell-state recovery arising from the next-nearest-neighbor (NNN) coupling present in the qubit device. Our results show that the Loschmidt echo is very sensitive to small perturbations during quantum-state evolution, in contrast to the quantities like qubit population that is often considered in the time-reversal experiment. These properties may be employed for the investigation of multiqubit system concerning many-body decoherence and entanglement, etc., especially when devices with reduced or vanishing NNN coupling are used.     

Modulation of energy spectrum and control of coherent microwave transmission at single-photon level by longitudinal field in a superconducting quantum circuit

We study the effect of longitudinally applied field modulation on a two-level system using superconducting quantum circuits. The presence of the modulation results in additional transitions and changes the magnitude of the resonance peak in the energy spectrum of the qubit. In particular, when the amplitude λ_z and the frequency ω_l of the modulation field meet certain conditions, the resonance peak of the qubit disappears. Using this effect, we further demonstrate that the longitudinal field modulation of the Xmon qubit coupled to a one-dimensional transmission line could be used to dynamically control the transmission of single-photon level coherent resonance microwave.     

基于折线形手征负折射介质结构的设计与仿真

分别设计和仿真了一种新型的工作在微波段和光波段的折线形手征介质结构.利用仿真得到的透射系数和反射系数反演计算了该结构的旋光角、椭偏度、相对介电常数、相对磁导率、手征参数以及折射率等参数.结果表明该结构在这两种波段下都显示出极大的旋光角和椭偏度,且因具有大的手征参数,而不再需要介电常数和磁导率同时为负就可实现左旋圆极化波(LCP)和右旋圆极化波(RCP)的负折射率. 关键词： 手征介质 旋光角 椭偏度 负折射率     

Fabrication of Josephson parameter amplifier and its applicationin squeezing vacuum fluctuations

Josephson parameter amplifier (JPA) is a microwave signal amplifier device with near-quantum-limit-noise performance. It has important applications in scientific research fields such as quantum computing and dark matter detection. This work reports the fabrication and characterization of broadband JPA devices and their applications in multi-qubit readout and squeezing of vacuum state. We use a process in which transmission lines and electrodes are made of niobium thin film and aluminum Josephson junctions are made by Dolan bridge technique. We believe this process is more convenient than the process we used previously. The whole production process adopts electron beam lithography technology to ensure high structural resolution. The test result shows that the gain value of the manufactured JPA can exceed 15 dB, and the amplification bandwidth is about 400 MHz. The noise temperature is about 400 mK at the working frequency of 6.2 GHz. The devices have been successfully used in experiments involving superconducting multi-qubit quantum processors. Furthermore, the device is applied to squeeze vacuum fluctuations and a squeezing level of 1.635 dB is achieved.     

无胺法合成高硅丝光沸石的表征

采用XRD、SEM、FT-IR、MAS NMR等表征手段, 对以氟离子为结构导向剂无胺法合成的高硅丝光沸石进行了表征. 结果表明: 高硅丝光沸石结构属立方晶系, 晶胞参数小于传统低硅丝光沸石, 但b、c值要比相近硅铝比非氟体系合成的丝光沸石样品的大; 样品形貌及粒径与其硅铝比有关, 表明晶化条件对产物形貌及粒径均有影响; 随硅铝比的增大, FT-IR光谱中450、544、1053 cm-1谱带向高频移动, 720 cm-1谱带强度减弱, 表明骨架中铝减少而硅增多; 采用含氟无胺体系合成高硅丝光沸石时基本上不会产生非骨架铝.     

双层纤维压电智能薄板几何非线性建模与分析

纤维压电MFC(Micro-Fiber Composite)的强致动力和高柔性等特点具有广泛的应用前景,但是材料组成结构复杂给建模带来了难处。基于Reissner-Mindlin假设,采用冯卡门非线性、中等转角及大转角几何非线性等理论,建立了MFC压电智能结构的多种几何非线性有限元模型。同时该模型考虑了压电纤维角度变化对结构形变的影响。分别对两种不同结构的MFC进行了建模与仿真,分别是MFC-d31和MFC-d33,前一种主要利用压电d31效应,而后一种主要利用压电d33效应。随后,通过一压电悬臂梁结构实验数据验证了模型的准确性。最后,利用所建模型对一种双层纤维压电智能薄板结构进行了几何非线性的计算与仿真。     

无胺体系高硅铝比丝光沸石的合成

Mordenite has two kinds of pore channels. The main straight channels of 0.67 nm ×0.70 nm (12-membered ring) parallel to the caxis are interconnected with small side-channels of 0.29 nm×0.57 nm (8-membered ring) parallel to the baxis.     

二维椭圆形散射转移斗篷的设计研究

基于变换光学理论设计了椭圆形散射转移斗篷,并推导了相应的本构参数张量表达式,根据得到的本构参数,利用基于有限元算法的软件分别对椭圆形介质柱、导体柱进行了全波仿真验证.仿真结果证实了所得本构参数的正确性,验证了散射转移斗篷可以模拟任意物体,包括介质、导体的幻象,这些结果为设计隐身斗篷提供了一种新的理论途径.     

Variational quantum simulation of thermal statistical states on a superconducting quantum processer

Quantum computers promise to solve finite-temperature properties of quantum many-body systems, which is generally challenging for classical computers due to high computational complexities. Here, we report experimental preparations of Gibbs states and excited states of Heisenberg $XX$ and $XXZ$ models by using a 5-qubit programmable superconducting processor. In the experiments, we apply a hybrid quantum-classical algorithm to generate finite temperature states with classical probability models and variational quantum circuits. We reveal that the Hamiltonians can be fully diagonalized with optimized quantum circuits, which enable us to prepare excited states at arbitrary energy density. We demonstrate that the approach has a self-verifying feature and can estimate fundamental thermal observables with a small statistical error. Based on numerical results, we further show that the time complexity of our approach scales polynomially in the number of qubits, revealing its potential in solving large-scale problems.