MIRAGE: Quantum Circuit Decomposition and Routing Collaborative Design Using Mirror Gates

Building efficient large-scale quantum computers is a significant challenge due to limited qubit connectivities and noisy hardware operations. Transpilation is critical to ensure that quantum gates are on physically linked qubits, while minimizing SWAP gates and simultaneously finding efficient decomposition into native basis gates. The goal of this multifaceted optimization step is typically to minimize circuit depth and to achieve the best possible execution fidelity. In this work, we propose MIRAGE, a collaborative design and transpilation approach to minimize SWAP gates while improving decomposition using mirror gates. Mirror gates utilize the same underlying physical interactions, but when their outputs are reversed, they realize a different or mirrored quantum operation. Given the recent attention to √iSWAP as a powerful basis gate with decomposition advantages over CNOT, we show how systems that implement the iSWAP family of gates can particularly benefit from mirror gates. Further, MIRAGE uses mirror gates to reduce routing pressure and reduce true circuit depth instead of just minimizing SWAPs. We explore the benefits of decomposition for √iSWAP and 4√SWAP using mirror gates, including both expanding Haar coverage and conducting a detailed fault rate analysis trading off circuit depth against approximate gate decomposition. We also describe a novel greedy approach accepting mirror substitution at different aggression levels within MIRAGE. For iSWAP systems that use square-lattice topologies, MIRAGE provides an average of 29.6% reduction in circuit depth by eliminating an average of 59.9% SWAP gates, with a relative decrease in infidelity of 28%. MIRAGE also improves circuit depth and decreases relative infidelity by 25% and 21 % for CNOT-based and 23% and 19% SYC-based machines, respectively.