RF Characterization on Nb-based Superconducting Silicon Interconnect Fabric for Future Large Scale Quantum Applications

To preserve delicate quantum signals (few hundreds to a few tens of µV), low-loss and low-crosstalk inter-dielet communication is a must in a wafer-scale integrated quantum system using Superconducting-IF. In this paper, inter-dielet links (short: 125 μm and 500 μm; long: 1750 μm) with L/S (2/2 and 5/5 μm) are characterized in a broadband 20 GHz range through simulation and experiments at 4K A compact assembly (inter-dielet spacing of 100 μm) through the quantum-compatible fine-pitch (10 um) Au interlayer is conducted. For insertion loss and crosstalk characterization, the simulated and measured results are presented to be low-loss (<1 dB) and low-crosstalk (< -23 dB) in the broadband 20 GHz range with short (≤ 500 um) and long (1750 um) links and two L/S (2/2 and 5/5 um). It is one of the first 20 GHz broadband RF characterization of short superconducting links (≤ 500 um) through advanced packaging for cryogenic inter-dielet quantum communication. This work brings large-scale quantum computing closer to being realized through compact heterogeneous integration.