Fine-Pitch (≤ 10 µm) Nb-based Superconducting Silicon Interconnect Fabric for Large-Scale Quantum System Application

To realize the potential of quantum computing, a compact integrated system with millions of qubits and control electronics is required. Existing analog schemes are challenging for the compact system with a high I/O density and wiring requirement. In this paper, a new digital assembly scheme providing high-density I/O (>10000 per mm²) is proposed. Qubits can be heterogeneously integrated with digital superconducting control electronics on a System-on-Wafer Superconducting Silicon Interconnect Fabric which is experimentally validated in this work. The key potential advantages include nanoseconds of control/readout cycle, 10^–4 qubit error rate, 0.2 mW system power dissipation per qubit. The dies can be assembled on the SoW platform with ≤ 100 µm inter-dielet spacing through the Au interlayer technology, which is demonstrated to be fine pitch (≤10 um), quantum-compatible (<150°C), mechanically robust (>30 MPa shear force), and electrically reliable down to 2 K. This work pushes quantum computing to highly scaled-out densely integrated qubits with superconducting controls.