ReQWIRE: Reasoning about Reversible Quantum Circuits

TitleReQWIRE: Reasoning about Reversible Quantum Circuits
Publication TypeJournal Article
Year of Publication2019
AuthorsRand, R, Paykin, J, Lee, D-H, Zdancewic, S
Start Page299-312
Type of ArticleIn Proceedings QPL 2018, arXiv:1901.09476

Common quantum algorithms make heavy use of ancillae: scratch qubits that are initialized at some state and later returned to that state and discarded. Existing quantum circuit languages let programmers assert that a qubit has been returned to the |0> state before it is discarded, allowing for a range of optimizations. However, existing languages do not provide the tools to verify these assertions, introducing a potential source of errors. In this paper we present methods for verifying that ancillae are discarded in the desired state, and use these methods to implement a verified compiler from classical functions to quantum oracles.