High-Kinetic Inductance Superconducting Technology for Quantum Applications

Superconducting materials present unique properties, which make a potential technological platform based on superconductors extremely appealing for a wide set of applications, both classical and not. Among these classes of materials, high-kinetic inductance "dirty" superconductors, i.e. superconductors rich in impurities, offer an extra layer of flexibility in terms of achievable impedance and compactness, with applications in a variety of electronics devices and in particular in the field of sensing. By controlling and fine-tuning the superconducting properties of dirty superconductors, it is possible to design both materials and devices for optimal performance. In this dissertation, we present a platform based on different variants of niobium nitride, which are employed for distinct families of applications. First, we discuss various ways to deposit thin films of dirty superconductors, with respective advantages and disadvantages, and potential relevant design strategies. Then, we focus on four main fields of applications. The first application regards three-dimensional integration, with the use of superconducting through-silicon vias and its integration within the superconducting platform. The second is sensing, i.e. single-photon sensing and current sensing, represented respectively by superconducting nanowire single-photon detectors and nanocryotrons. Thirdly, circuits based on compact resonating structures are discussed for their applications in circuit quantum electrodynamics, first by assessing the role of kinetic inductance for internal loss and nonlinearity, and then by producing compact impedance matching structures and filters. Lastly, we present a superconducting transmon qubit based on classical superconducting materials, to be used as reference for high kinetic inductance qubits to be developed in the future.