Engineering a Multi-Mode Purcell Filter for Superconducting-Qubit Reset and Readout with Intrinsic Purcell Protection

This project represents deep-tech hardware engineering for superconducting quantum computing. While it has 0 stars, the 19 forks are a highly significant signal in the niche quantum hardware community, indicating that researchers are actively cloning the repository to replicate or adapt the design for physical fabrication. The defensibility is high (7) because it requires extreme domain expertise in microwave engineering and quantum coherent dynamics; it is not something a generalist can reproduce. The 'moat' is the specific geometric and parametric configuration of the multi-mode resonator which provides 'intrinsic' protection, reducing the footprint of the QPU—a critical requirement for scaling to error-correction densities. Frontier labs (OpenAI/Anthropic) have zero interest in this space, as it is deep in the physical layer. However, industry giants like Google Quantum AI, IBM, and Rigetti are the primary competitors. The displacement horizon is long (3+ years) because hardware changes require new fabrication runs (lithography, deposition, packaging), which have much slower cycles than software. The main risk is not a frontier lab, but a dominant hardware player like IBM standardizing a different filter architecture that becomes the industry norm.