可扩展超导量子处理器芯片中电压控制可调耦合器的研究

量子计算相比于经典计算在解决大数因子分解和无序数据库搜索等问题上具有显着优势。目前最有希望实现量子计算的实验方案是超导量子比特，而实现量子计算，尤其是大规模量子计算的必要条件就是量子比特之间的相干耦合。因此，本文对可应用于可扩展超导量子处理器芯片中的电压控制可调耦合器进行了研究。 超导量子比特是超导量子电路的核心器件，其退相干时间一直都被科研人员们关心。各种实验表明，电路量子电动力学（Circuit QED）架构下的超导量子比特（transmon、Xmon等）具有较长的退相干时间，且该架构非常适合应用在超导量子测量实验，因此本文的所有实验都是在该架构下展开的。 本文针对电压控制可调耦合器的设计提出了三种方案，最后是用电荷量子比特实现的。在超导量子测量平台上对所设计的带有电压控制可调耦合器的样品进行测量后发现其具有电压可调谐性，说明方案可行。除此之外，本文还研究了相滑移结(Phase-slip Junction)电压控制可调耦合器，它来源于磁通和电荷相互对偶的现象，最后用氮化铌材料设计了微波谐振腔以及相滑移结电压控制可调耦合器所需的10μH电感，从仿真和实验结果中可以看出，它同样适用于可扩展超导量子处理器芯片。

Compared with classical computing, quantum computing has obvious advantages in solving problems such as factorization of large numbers and searching disordered databases. At present, the most promising experimental scheme for quantum computing is superconducting qubits, and the necessary condition for realizing quantum computing, especially large-scale quantum computing, is the coherent coupling between qubits. Therefore, the voltage-controlled tunable coupler which can be used in the scalable superconducting quantum processor chip is studied in this paper. Superconducting qubit is the core device of superconducting quantum circuit, and its decoherence time has always been concerned by researchers. Various experiments show that superconducting qubits (transmon, Xmon, etc.) in the circuit quantum electrodynamics (QED) architecture have long decoherence times. This architecture is also suitable for superconducting qubits’ quantum measurement experiments, so all the experiments in this thesis are carried out in this architecture. In this paper, three schemes are proposed for the voltage-controlled tunable coupler, finally it is realized by a charge qubit. After measuring the designed sample with voltage-controlled tunable coupler on the superconducting quantum measurement platform, it is found that it has voltage tunability, which shows that the scheme is feasible. In addition, this article also studies the phase-slip junction voltage-controlled tunable coupler, which is derived from the phenomenon of magnetic flux and charge mutual duality. Finally, the microwave resonant cavity and the 10μH inductor required by the phase-slip junction voltage-controlled tunable coupler are designed with niobium nitride material. From the simulation and experimental results, it can be seen that it is also suitable for scalable superconducting quantum processor chips.