1. Institute of Ion Beam Physics and Materials Research Helmholtz‐Zentrum Dresden‐Rossendorf 01328 Dresden Germany
2. Experimental Physics 6 and Würzburg‐Dresden Cluster of Excellence ct.qmat Julius‐Maximilian University of Würzburg 97074 Würzburg Germany
3. Jet Propulsion Laboratory California Institute of Technology Pasadena CA 91109 USA
4. Department of Quantum Science and Energy Engineering Graduate School of Engineering Tohoku University 6‐6‐01‐2, Aza‐Aoba, Aramaki, Aoba‐ku Sendai 980‐8579 Japan
5. National Institutes for Quantum Science and Technology Takasaki Gunma 370‐1292 Japan
6. Department of Materials Science Tohoku University 6‐6‐02 Aramaki‐Aza, Aoba‐ku Sendai 980‐8579 Japan
7. Technische Universität Dresden 01062 Dresden Germany