Introducing Hardware Awareness to PCOAST Synthesis

The Pauli-based Circuit Optimization Analysis and Synthesis Toolchain (PCOAST) was recently introduced as a method for the optimization of quantum circuits and implemented as the primary optimization method in the Intel® Quantum Software Development Kit. Though PCOAST includes optimizations on the PCOAST graph representation, the highly efficient outcomes are primarily due to the PCOAST circuit synthesis of the graph. However, PCOAST synthesis as originally introduced is agnostic to hardware constraints such as limited connectivity or faulty gates. In this talk, we discuss the extension of PCOAST synthesis to include constraints by extending the definitions of the synthesis search functions. We adapt common graph-based data structures to choose among the limited set of two-qubit gates when they are generated. This avoids costly SWAPs by leveraging a better realization of arbitrary Pauli operator nodes in the context of the whole circuit as well as the hardware. We also argue that the algorithmic complexity of hardware awareness is on par with PCOAST synthesis without it.