1. FOM Institute for Atomic and Molecular Physics AMOLF, 1098XG Amsterdam, The Netherlands
2. Biomedical Photonics, Department of Physics, University of Gothenburg, 412 96 Göteborg, Sweden
3. Molecular Microscopy, Department of Chemical and Biological Engineering, Chalmers University of Technology, 412 96 Göteborg, Sweden
4. Bionanophotonics, Department of Applied Physics, Chalmers University of Technology, 412 96 Göteborg, Sweden