超导量子电路中大原子的探索研究

STUDY OF GIANT ATOMS IN SUPERCONDUCTING QUANTUM CIRCUITS

杨清

11930049

硕士

材料工程

谭电

2021-05-21

2021-06-15

南方科技大学

深圳

超导量子比特目前被广泛认为是实现量子计算最有潜力的平台。和其它类型的量子比特相比，超导量子比特平台在多比特集成、比特读取精度和操作保真度等方面都有着较大的优势，但较短的退相干时间一直是制约其发展的重大因素。本文聚焦于困扰超导量子比特的重要问题——相干时间过短，分析了比特退相干的原理和主要噪声来源，引入了通过大原子提高比特退相干时间的方案。不同于常见的提高比特退相干时间的保护机制，大原子在极大提升退相干时间的同时，还能保留比特与外界较强的相互作用，从而不影响读取精度和门操作的保真度。大原子与小原子的区别核心在于大原子能够和其对应的波实现多点耦合，并且这些耦合点之间可以产生相互作用，从而在很多方面表现出迥异于小原子的性质。其中最重要的一点就是退相干时间的提高。此外，受益于其独特的性质，大原子也为更深层次探究物理问题提供了一个崭新的平台。已经在小原子体系下进行的某些相关研究可能会在大原子体系下得到完全不同的结果。因此基于大原子平台重新进行一些物理现象的探究也是很有意义的工作。本文介绍了大原子性质的理论推导，从量子光学中光与物质的相互作用出发阐释了大原子是如何实现其退相干时间相关于0，1能级之间的转变频率，从而实现退相干时间的延长的。在理论基础上还介绍了实现大原子的两种实验平台，分别基于表面声波和一维蜿蜒传输线；提出了使用HBAR来实现大原子的一种方案，此外还针对实验做了一些前期的准备和仿真工作。最后指出，大原子除了提高退相干时间这一优势外，利用大原子进行量子光学的相关研究也是目前的一大趋势。

Superconducting quantum bits are now widely considered as the most promising platform for realizing quantum computing. Compared with other types of quantum bits, superconducting quantum bit platforms have major advantages in terms of multi-bit integration, and readout accuracy and manipulation fidelity, but the short decoherence time has been a major constraint to its development.In this paper, we focus on the short decoherence time, an important problem plaguing superconducting quantum bits. We analyze the principle of decoherence and the main noise sources, and introduce a scheme to improve the decoherence time by giant atoms. Unlike the common protection mechanisms to improve the decoherence time, giant atoms greatly improve the decoherence time while preserving the stronger interaction between the bits and the environment, thus not affecting the read accuracy and the fidelity of the gate operation.The core difference between giant and small atoms lies in the ability of giant atoms to achieve multiple points of coupling with their wave counterparts and the inference between these coupling points, thus exhibiting properties very different from those of small atoms in many ways. One of the most important points is the increase in decoherence time. In addition, thanks to their unique properties, giant atoms also provide a new platform for deeper investigation of physical problems. Some relevant studies already performed in the small-atom regime may yield completely different results in the giant-atom regime. Therefore, it is also interesting to re-investigate some physical phenomena based on the giant atom platform.In this paper, we present the theoretical derivation of the properties of giant atoms and explain how giant atoms achieve their decoherence time related to the transition frequency between the 0,1 level and thus the extension of the decoherence time in terms of the interaction of light with matter in quantum optics. On the basis of the theory, two experimental platforms for realizing giant atoms are presented, based on surface acoustic waves(SAWs) and one-dimensional meandering transmission lines, respectively; a scheme for using HBAR to realize giant atoms is proposed, in addition to some preliminaries and simulations for the experiments setup. Finally, it is pointed out that in addition to the advantage of improving the decoherence time, the use of giant atoms for research related to quantum optics is also a major trend at present.

超导量子比特 大原子 退相干 HBAR

superconducting qubits giant atoms decoherence HBAR

中文

独立培养

南方科技大学

杨清. 超导量子电路中大原子的探索研究[D]. 深圳. 南方科技大学,2021.