1. University of Strathclyde, 26 Richmond Street, Glasgow G1 1XH, UK
2. Cambridge Quantum Computing Ltd, 9a Bridge Street, Cambridge CB2 1UB, UK
3. Department of Computer Science, University of Oxford
4. CNRS LORIA, Inria-MOCQUA, Université de Lorraine, F 54000 Nancy, France
5. Institute for Computing and Information Sciences, Radboud University Nijmegen