Monolithic Al/Ge/Al nanostructures: a novel platform for quantum sensing and photodetection

Recent advances in monolithic Al/Ge/Al nanostructures have demonstrated their remarkable versatility as platforms for integrated quantum technologies. These nanostructures leverage the unique properties of aluminum, which transitions to a superconducting state at cryogenic temperatures, and germanium, a CMOS-compatible semiconductor with excellent optoelectronic performance. In this talk, we will present the transition of these devices from bottom-up fabrication methods, where phenomena such as Coulomb blockade and quantum ballistic transport were observed, to a more scalable and controlled top-down approach. This improved fabrication strategy enables precision engineering of nanostructures, which have demonstrated remarkable performance for plasmonics, electronics, and photonic applications. Furthermore, we will show the ongoing development of these devices as superconducting quantum interference devices (SQUIDs), emphasizing their potential for quantum sensing applications. The combination of materials and fabrication methods positions these monolithic Al/Ge/Al nanostructures as a pioneering and multifunctional solution for advancing integrated photonics and quantum metrology.