SEQC: Stratify-Elaborate Quantum Compilation Towards Modular Hybrid Architectures

As quantum computing technology matures, the pursuit of performance and scalability has led to the widespread adoption of modular quantum architectures. We expect that the next stage of technological evolution will integrate multiple qubit modalities into these systems, producing hybrid, modular quantum architectures. However, the complexity of hybrid, modular quantum devices, coupled with their growing sizes, presents an imminent scalability challenge for quantum compilation. Existing qubit allocation methods are often unable to contend with inter-module links, which do not necessarily support a universal basis gate set. Furthermore, these algorithms are typically not designed for qubit links of significantly varying latency or fidelity. In this work, we propose SEQC, a hierarchical parallelized compilation pipeline optimized for modular quantum systems, including several novel methods for qubit placement, qubit routing, and circuit optimization. SEQC attains a 9.3-32.3% average increase in circuit fidelity (49.99-63.36% max), depending on the chiplet size and topology. Additionally, owing to its ability to parallelize compilation, SEQC achieves 1.34-3.27$\times$ faster compilation on average (3.37-6.74$\times$ max) over a chiplet-unaware Qiskit baseline.