CIQS: A Scalable Pipeline for Processing Quantum Circuits Beyond 1,000,000 Qubits

CIQS (Causal Iteration Quantum Solution) is a fully analytic, plug-and-play quantum circuit compilation pipeline. It scales to 1, 000, 000 qubits at linear cost, with: no simulation no approximation, no heuristic search, no tunable parameters. Composed of a mapper/router and an optimizer, it natively handles quDits of any dimension (qubit, qutrit, ququart, and above) with no additional parameters required. The optimizer scans the circuit once and applies three removal passes in sequence: removes individual redundant gates, the group certificate removes gate sequences impossible to remove individually, the hardware calibration pass removes gates the target device cannot execute faithfully, at zero fidelity cost, based on vendor-supplied hardware calibration data. Benchmarked with IBM's Benchpress framework across four circuit families and two hardware topologies, on an AMD Ryzen 5 (2019 consumer desktop, 32 GB RAM). Raw benchmark data provided as ancillary files (AncillaryData₁00k. json, 1ₘillionqubitsDATA. json). Free licenses are available for academic research use. Edit (v2): One numerical error in v1 corrected. Edit (v3): Benchmark extended to 1, 000, 000 qubits. Native quDit support added. Hardware calibration pass added.