Superconducting Nanowire Technology for Microwave and Photonics Applications

Abstract

Quantum computing and quantum communication are innovative technologies promising to revolutionize several aspects of our societal landscape. However, early cutting-edge experiments are rapidly approaching significant scalability roadblocks. As the qubit count increases, superconducting quantum processors require an increasing number of control and readout electronic devices, which are incompatible at scale with the performance of dilution refrigerators. Photonic-based platforms struggle with integration issues due to operational, design, and heterogeneous material compatibility.

In this thesis, we demonstrate that superconducting nanowires have the potential to drive a major leap in the scalability of these and other architectures. We show that the exotic microwave properties of superconducting nanowires enable cryogenic devices at microwave frequencies with an ultra-compact footprint. We introduce microwave directional couplers and resonators featuring a footprint reduction of up to 200 times, making them suitable for on-chip integration with superconducting quantum processors and in any application needing cryogenic microwave signal processing.

Furthermore, we engineer the nanowire properties to overcome the metrics trade-offs of single-photon detectors. We demonstrate an all-in-one nanowire detector with record performances, imaging capabilities, and photon-number resolution capabilities, all in the same design. Our device can be used to scale experiments needing many high-performance detectors.

Finally, we demonstrate single-photon detectors integrated on lithium-niobate-on-insulator with state-of-the-art performance. We also introduce integrated array technology on silicon-on- insulator. Our nanowire technology can be on-chip heterogeneously integrated with current quantum photonic platforms, removing the need for out-coupling to fiber-coupled detectors.

In conclusion, superconducting nanowires have the potential to become a comprehensive solution for scaling classical and quantum architectures.