About the Authors
Foundation for Fundamental Research on Matter (FOM) Institute for Atomic and Molecular Physics, Amsterdam, The Netherlands
The authors have declared that no competing interests exist.
Conceived and designed the experiments: ST-N PRtW. Performed the experiments: ST-N PRtW. Analyzed the data: ST-N PRtW. Contributed reagents/materials/analysis tools: ST-N PRtW. Wrote the paper: ST-N PRtW.