1. Inria, Paris, France
2. Instituto de Ciencias Matemáticas (CSIC-UAM-UC3M-UCM), C/Nicolás Cabrera 13-15, Campus de Cantoblanco, 28049 Madrid, Spain
3. Department of Mathematics, Technische Universität München, 85748 Garching, Germany
4. Munich Center for Quantum Science and Technology (MCQST), München, Germany
5. California Institute of Technology, 1200 E California Blvd., MC 305-16, Pasadena, California 91125, USA
6. Departamento de Análisis Matemático y Matemática Aplicada, Universidad Complutense de Madrid, 28040 Madrid, Spain