MCQA: Multi-Constraint Qubit Allocation for Near-FTQC Device

In response to the rapid development of quantum processors, quantum software must be advanced by considering the actual hardware limitations. Among the various design automation problems in quantum computing, qubit allocation modifies the input circuit to match the hardware topology constraints. In this work, we present an effective heuristic approach for qubit allocation that considers not only the hardware topology but also other constraints for near-fault-tolerant quantum computing (near-FTQC). We propose a practical methodology to find an effective initial mapping to reduce both the number of gates and circuit latency. We then perform dynamic scheduling to maximize the number of gates executed in parallel in the main mapping phase. Our experimental results with a Surface-17 processor confirmed a substantial reduction in the number of gates, latency, and runtime by 58%, 28%, and 99%, respectively, compared with the previous method [18]. Moreover, our mapping method is scalable and has a linear time complexity with respect to the number of gates.