A Verified Optimizer for Quantum Circuits

TitleA Verified Optimizer for Quantum Circuits
Publication TypeJournal Article
Year of Publication2021
AuthorsHietala, K, Rand, R, Hung, S-H, Wu, X, Hicks, M
JournalProceedings of the ACM on Programming Languages
Date Published11/12/2020

We present VOQC, the first fully verified compiler for quantum circuits, written using the Coq proof assistant. Quantum circuits are expressed as programs in a simple, low-level language called SQIR, which is deeply embedded in Coq. Optimizations and other transformations are expressed as Coq functions, which are proved correct with respect to a semantics of SQIR programs. We evaluate VOQC's verified optimizations on a series of benchmarks, and it performs comparably to industrial-strength compilers. VOQC's optimizations reduce total gate counts on average by 17.7% on a benchmark of 29 circuit programs compared to a 10.7% reduction when using IBM's Qiskit compiler.