Phase gadget synthesis for shallow circuits

Alexander Cowtan, Silas Dilkes, Ross Duncan, Will Simmons, Seyon Sivarajah

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

33 Citations (Scopus)
120 Downloads (Pure)


We give an overview of the circuit optimisation methods used by tket, a compiler system for quantum software developed by Cambridge Quantum Computing Ltd. We focus on a novel technique based around phase gadgets, a family of multi-qubit quantum operations which occur naturally in a wide range of quantum circuits of practical interest. The phase gadgets have a simple presentation in the ZX-calculus, which makes it easy to reason about them. Taking advantage of this, we present an efficient method to translate the phase gadgets back to CNOT gates and single qubit operations suitable for execution on a quantum computer with significant reductions in gate count and circuit depth. We demonstrate the effectiveness of these methods on a quantum chemistry benchmarking set based on variational circuits for ground state estimation of small molecules.
Original languageEnglish
Title of host publicationProceedings 16th International Conference on Quantum Physics and Logic
EditorsBob Coecke, Matthew Leifer
Place of PublicationWaterloo, Australia
PublisherOpen Publishing Association
Number of pages26
Publication statusPublished - 10 Jun 2019
Event16th International Conference on Quantum Physics and Logic 2019 - Chapman University, Orange, United States
Duration: 10 Jun 201914 Jun 2019
Conference number: 16th

Publication series

NameElectronic Proceedings in Theoretical Computer Science
PublisherOpen Publishing Association.
ISSN (Print)2075-2180


Conference16th International Conference on Quantum Physics and Logic 2019
Abbreviated titleQPL 2019
Country/TerritoryUnited States


  • quantum computation
  • noisy intermediate-scale quantum
  • quantum software
  • compilations


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