Photolithography-Compatible Three-Terminal Superconducting Switch for Driving CMOS Loads

Abstract

Superconducting devices have enabled breakthrough performance in quantum sensing and ultra-low-power computing. Nevertheless, the need for a cryo-electronics platform that can interface superconductor electronics with Complementary Metal-Oxide-Semiconductor (CMOS) devices has become increasingly evident in many cutting-edge applications. In this work, we present a three-terminal micrometer-wide superconducting wire-based cryotron switch (wTron), fabricated using photolithography, that can directly interface with CMOS electronics. The wTron features an output impedance exceeding 1 k$Ω$ and exhibits reduced sensitivity to ambient magnetic noise, similar to its nanoscale predecessor, the nanocryotron. In addition, its micrometer-wide wires support switching currents in the mA range, making wTrons well-suited for driving current-hungry resistive loads and highly capacitive CMOS loads. We demonstrate this capability by using the wTron to drive room-temperature CMOS electronics, including an LED and a MOSFET with a gate capacitance of 500 pF. We then examine the optimal design parameters of wTrons to drive CMOS loads, such as MOSFETs, HEMTs, and electro-optic modulators. Furthermore, to demonstrate the foundry readiness of the wTron, we fabricated wTrons using MIT Lincoln Laboratory's SFQ5ee superconducting process and characterized their switching behavior. Our work shows that wTron will facilitate the interface between superconductor electronics and CMOS, thereby paving the way for the development of foundry-compatible cryo-electronic ecosystems to advance next-generation computing and quantum applications.