尽管经典电子计算机能够满足现代人生活和学习的绝大部分需求，但是它在计算能力上仍存在一定的局限性。而利用量子比特的叠加性和纠缠态人们可以构造某些量子算法，这些量子算法的计算速度要远远超过电子计算机的计算速度。此外还可以利用量子比特模拟分子和原子的特性，对于材料和医药学的研究有很大的帮助。本论文以Xmon量子比特为基础，在量子比特的选择、量子计算机的物理实现、单个量子比特的参数设计以及多量子比特芯片版图设计等方面进行了较为系统而全面的研究。同时提出了用于多量子比特系统的控制复用方案。论文的引言部分首先介绍了为什么在电子计算机的基础上我们还需要一台量子计算机，然后针对已有的各种量子比特进行简单分析，说明了选择其中一种量子比特作为设计单元的理由。接着介绍了利用量子算法如何去破解RSA密码算法。并指出量子计算机的研究目前还面临着哪些挑战。从Xmon的制备工艺开始，简单介绍了双层胶制备工艺与双角度蒸发制备工艺。将芯片封装之后，放进稀释制冷机开始降温。能谱测试含有确认量子比特的存在性、寻找量子比特的频率和量子比特的能谱表征等步骤，涉及到单光子和多光子跃迁过程、光子劈裂效应、真空拉比劈裂、色散测量等。时域测试包含对量子比特退相干时间的表征，涉及到拉比振荡和自旋回波测试。实现量子算法需要单比特量子门加任意一种通用双比特量子门组合完成。论文的研究重点在于如何去设计超导量子计算芯片的版图尺寸，根据设定的量子比特频率与非谐性结合约瑟夫森结的工作原理推导出约瑟夫森能与电容充电能，进而转化为氧化时间与十字电容尺寸。然后从腔量子电动力学出发研究了量子比特与超导共面波导谐振腔之间的耦合系数、耦合电容与叉指电容的尺寸。在此基础上调整谐振腔的长度。以设计的单量子比特为基础，绘制了不同版本的总线制8位超导量子计算芯片，详细分析了设计改进的理由。以多量子比特芯片为基础，提出了一种可用于减少输入端口的控制复用方案。最后分析了单层布线结构下可容忍的Xmon量子比特的极限数量。
Although classical computer can meet the needs of modern life and learning, it still has some limitations in calculation ability. By using the superposition and entanglement of quantum bits, some quantum algorithms can be constructed, and the computing speed of these quantum algorithms is much faster than that of electronic computers. In addition, quantum bits can also be used to simulate the properties of molecules and atoms, which is helpful to the research of materials and medicine. This thesis is based on the Xmon quantum bits, quantum bit selection, physical realization of quantum computers, parameter design of single qubit and multi-qubit chip layout design are studied. Meanwhile, a multiplex control scheme for multi-qubit system is proposed.The introduction part first introduces why we need a quantum computer based on the electronic computer. Then, a simple analysis is made on the existing qubits, and the reasons for choosing one of the qubits as the design elements are explained. Followed by an introduction to how to use the quantum algorithm to crack RSA password algorithm. Challenges in research of quantum computer are pointed out.Starting from the preparation process of Xmon qubit, we investigated the double-layer photoresist technique and the double angle evaporation technique. After the chip package, it’s put into the dilution refrigerator to be cooled. The spectrum test consists of the confirmation of qubit’s existence, search of qubit’s frequency and characterization of quantum energy spectrum, involving single photon and multi-photon transitions, photon number splitting effect, Vacuum Rabi splitting, dispersion measurement etc.. The time domain test includes the characterization of the decoherence time of the qubit, which involves Rabi oscillation and spin echo test. Quantum algorithm can be realized by the combination of single qubit gates and an arbitrary general double bit quantum gate.This thesis focuses on how to design the layout size of superconducting quantum computing chip. Based on qubit’s frequency and anharmonicity and the working principle of Josephson junction, we can derive Josephson energy and capacitor charging energy, which can be converted to oxidation time and cross capacitor size. Then, we started from the cavity quantum electrodynamics to research on the coupling coefficient between qubit and superconducting coplanar waveguide resonator, the coupling capacitance and the dimensions of capacitor’s claw. On this basis, the length of the whole cavity is adjusted. Based on the design of a single qubit, different versions of the 8-qubit superconducting quantum computing chip are drawn, and the reasons for the design improvement are analyzed in detail. Based on the multi-qubit chip, this paper proposes a new multiplex control scheme for reducing the input port. At last, the limit number of tolerable Xmon quantum bits in a single layer wiring structure is analyzed.
