Kengo Hirata developed experimental support for quantum circuit modifiers in the CQCL/guppylang and CQCL/tket2 repositories, focusing on enhancing language expressiveness and circuit tooling. He implemented AST to CFG lowering and type checking for modifiers such as control, dagger, and power in Guppy, enabling richer control-flow constructs and more robust error handling. In tket2, he consolidated modifier and global phase handling for Hugr/Tket integration, introducing extension operations and a resolver to rewrite and decompose circuits. Using Python and Rust, Kengo’s work deepened the infrastructure for quantum workflows, reducing future rework and accelerating the delivery of advanced circuit features.