Abstract: With Google's successful demonstration of " quantum supremacy" in 2019，the research of

supercon- ducting quantum computing is attracting more and more attention around the globe.

Superconducting quantum bits ( qubits) are macroscopic devices with fundamental quantum

properties such as energy-level quantization，quantum- state superposition and quantum-state

entanglement. They provide an excellent platform for the studies in many fields such as

quantum physics，atomic physics，quantum optics，quantum chemistry，quantum simulation，quantum

computing，and so on. In this article，we discuss the basic principles and structures of the

superconducting phase-， charge-，transmon-，and flux-type qubits，as well as their device

design and fabrication process. We also present a brief introduction to the rich research

areas based upon the superconducting qubit architecture.

Key words: superconducting qubit, qubit fabrication, quantum-state measurement, quantum simulation, quantum computing