Scalable Nanofabrication of High-Quality YBa 2 Cu

The realization of superconducting single-photon detectors operating above the liquid-helium temperature is currently the focus of intense research efforts. Here, we present the fabrication of ultraclean encapsulated nanowires from commercially available thin films of $\mathrm{YBa}$${}_{2}$$\mathrm{Cu}$${}_{3}$$\mathrm{O}$${}_{7\ensuremath{-}\ensuremath{\delta}}$ by high-energy oxygen-ion irradiation. The structured nanowires, ranging from 0.1 to $5\phantom{\rule{0.2em}{0ex}}\text{\ensuremath{\mu}}\mathrm{m}$ in width, exhibit sharp resistive transitions to the superconducting state above 85 K. The $I$-$V$ characteristics reveal that the evolution from the superconducting to the normal state shows a large voltage jump in the volt range. This demonstrates that the entire nanowire transits---a prerequisite for the development of a hot spot upon absorption of a single photon. Our results pave the way for the fabrication of $\mathrm{YBa}$${}_{2}$$\mathrm{Cu}$${}_{3}$$\mathrm{O}$${}_{7\ensuremath{-}\ensuremath{\delta}}$-based scalable superconducting single-photon-detection devices.