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:

1. Pass1 removes individual redundant gates,
2. Pass2 removes gate sequences impossible to remove individually,
3. Pass3 removes gates the target device cannot execute faithfully, at zero fidelity cost, based on vendor-supplied hardware calibration data.

Benchmarked with IBM's Benchpress suite 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 (Ancillary_Data_100k.json & 1_million_qubits_DATA.json).

**CIQS has now a new optional 1:5 Error Correction module, necessary only for matter qubits: More on the 1:5 error correction

The CIQS pipeline including CIQM (mapper/router) and CIQO (optimizer) is freely available for non-commercial use:

https://github.com/GamesOfArcadia/ciqs

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.

Edit (v3) March 30th: Minor editing mistakes corrected.