Large-Scale Quantum System Design on Nb-based Superconducting Silicon Interconnect Fabric

Yu-Tao Yang and Subramanian Iyer


For quantum systems up to millions of qubits, I/O and wiring, signal latency, qubit control/readout, and system thermal budget are challenging. Instead of using current microwave analog controlling systems, a novel scheme for qubit control using superconducting Single Flux Quantum (SFQ) digital electronics integrated on a System-on-Wafer (SoW) Superconducting Silicon Interconnect Fabric (Superconducting IF) is proposed. The new integration scheme leverages a very-fine interconnect pitch <10 μm, a picosecond interconnect latency, and a potential nanosecond qubit control/readout cycle latency, as well as a prospective four orders of magnitude reduction in power dissipation per qubit. A fine interconnect pitch enables a high-density I/O >10000 per mm2 and dense wiring levels. A picosecond interconnect latency is attained by a short ( ~60 μm) lateral inter-dielet spacing and a low profile (≤ 1 μm) die-attach. We demonstrate the superconducting SoW in this work with proximal superconducting dielets. The key challenges to realize this design scheme and corresponding solutions are discussed. The proposed design of large-scale qubits with SFQ controls assembled on the Superconducting IF in this work is able to fulfill the true potential of quantum computing.