1. Institute for Quantum Computing and Department of Combinatorics and Optimization, University of Waterloo, Waterloo, Ontario, Canada
2. Perimeter Institute for Theoretical Physics, Waterloo, Ontario, Canada
3. ICREA & Física Teórica: Informació i Fenómens Quàntics, Departament de Física, Universitat Autònoma de Barcelona, ES-08193 Bellaterra, Barcelona, Spain
4. Centre for Quantum Software and Information, Faculty of Engineering and Information Technology, University of Technology Sydney, NSW 2007, Australia