可扩展超导量子器件的设计与制备

DESIGN AND FABRICATION OF SCALALBE SUPERCONDUCTING QUANTUM DEVICES

周宇轩

11849209

硕士

物理学

俞大鹏

2020-05-27

2020-07-08

哈尔滨工业大学

深圳

量子计算因其杰出的并行计算能力在全世界范围内备受瞩目，而基于约瑟夫森结的超导量子计算路线更因其具有良好的可扩展性和可操作性被视为最可能实现通用量子计算的方案之一。尽管近些年来在超导量子计算领域出现了一些令人鼓舞的进展，但是目前我们能在实验上实现的超导量子线路和通用量子计算机仍然有着很大的距离。对于超导量子计算来说，为了构建具有足够多逻辑比特，能够进行实用化计算的量子线路可能需要数百万个物理量子比特，而目前领域内大部分进行实验的量子计算芯片至多包含几十个量子比特。所以设计与开发具有可扩展性的量子线路架构和加工工艺对未来超导量子计算机的研制具有极其重要的意义。本文主要介绍了超导量子比特的相关原理与设计方法，并对包括薄膜沉积，图形转移以及封装等在内的微纳加工流程进行了详细的阐述，之后列举了一些在加工中遇到的问题并给出了相应的解决方案。本论文也简要介绍了当前正在使用的超导量子计算低温测量系统，同时介绍了为超导量子计算芯片提供极低温测量环境的核心设备——稀释制冷机的原理。量子计算优势的实现很大程度上依赖于实验上对量子计算芯片内多比特的高精度同步操控和快速表征。研发新型可扩展量子计算处理器为以上问题提供了有效解决方案。本文提出了一个自主设计和研发的具有可扩展性能的超导量子比特方案，这是一种用于两比特之间耦合器开关的可扩展方案，该开关通过调制耦合器频率来控制两个量子比特间的耦合。该方案在硬件上与现有的超导量子比特器件兼容，并且可以得到更高的门保真度。

Nowadays, quantum computation has a higher profile in the world due to its excellent parallel computation ability. Superconducting quantum computation which based on Josephson junction is regarded as one of the most likely methods to realize quantum computation due to its outstanding scalability and operability. Although a rapid progress has been made in the field recently, there is a great distance between the devices we operate on experiments and the universal quantum computer. One of the main reasons is that millions of physical qubits are required to build enough logical qubits to do some useful computations; nevertheless, there are only tens of physical qubit on the quantum devices we operate. Therefore, developing a mature and scalable qubit device process according to the requirements of the experiment has great significance in the future.This dissertation systematically and deeply analyzes the principles and design methods of superconducting qubit device. The micro-nano fabrication processes including deposition, patterning and packaging are also elaborated in this dissertation. Some encountered problems in processing are listed and the appropriate solutions are given. We also give an overview of our experimental system and a brief introduction to the principle of dilution refrigerator which provide the ultra-low temperature measurement environment for superconducting qubit.The advantages of quantum computation mainly depend on the high-precision simultaneous control and rapid characterization of quantum information processors. We demonstrate a scalable scheme of tunable coupler between two qubits. We are able to control the coupling strength between two qubits by modulating the coupler frequency. The scheme is compatible with our existing device and it promises a higher gate fidelity with current technologies.

超导量子比特 约瑟夫森结 可调耦合 芯片工艺开发

superconducting qubit Josephson junction tunable coupler chip process development

中文

联合培养

南方科技大学

周宇轩. 可扩展超导量子器件的设计与制备[D]. 深圳. 哈尔滨工业大学,2020.