A number of current approaches to quantum and neuromorphic computing use superconductors as the basis of their platform or as a measurement component, and will need to operate at cryogenic temperatures. Semiconductor systems are typically proposed as a top-level control in these architectures, with low-temperature passive components and intermediary superconducting electronics acting as the direct interface to the lowest-temperature stages. The architectures, therefore, require a low-power superconductorsemiconductor interface, which is not currently available. Here we report a superconducting switch that is capable of translating low-voltage superconducting inputs directly into semiconductor-compatible (above 1,000 mV) outputs at kelvin-scale temperatures (1K or 4K). To illustrate the capabilities in interfacing superconductors and semiconductors, we use it to drive a light-emitting diode (LED) in a photonic integrated circuit, generating photons at 1\,K from a low-voltage input and detecting them with an on-chip superconducting single-photon detector. We also characterize our devices timing response (less than 300 ps turn-on, 15 ns turn-off), output impedance (greater than 1Ω), and energy requirements (0.18fJ/um^2, 3.24 mV/nW).
superconductor, switch, thermal, photonic, led