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 texttt{SWAP} gates and simultaneously finding efficient decomposition into native textit{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 textit{MIRAGE}, a collaborative design and transpilation approach to minimize texttt{SWAP} gates while improving decomposition using textit{mirror gates}. Mirror gates utilize the same underlying physical interactions, but when their outputs are reversed, they realize a different or textit{mirrored} quantum operation. Given the recent attention to sqrt{texttt{iSWAP}} as a powerful basis gate with decomposition advantages over texttt{CNOT}, we show how systems that implement the texttt{iSWAP} family of gates can benefit from mirror gates. Further, textit{MIRAGE} uses mirror gates to reduce routing pressure and reduce true circuit depth instead of just minimizing texttt{SWAP}s. We explore the benefits of decomposition for sqrt{texttt{iSWAP}} and sqrt[4]{texttt{iSWAP}} 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. Finally, for texttt{iSWAP} systems that use square-lattice topologies, textit{MIRAGE} provides an average of 29.6% reduction in circuit depth by eliminating an average of 59.9f% texttt{SWAP} gates, which ultimately improves the practical applicability of our algorithm.