1. Quantum Nano Photonics Group, Department of Applied Physics, Royal Institute of Technology (KTH), Stockholm 106 91, Sweden
2. Department of Mechanical and Process Engineering, ETH Zurich, CH - 8092 Zurich, Switzerland
3. Optics Group, Delft University of Technology, Delft 2628 CJ, The Netherlands
4. Department of Electronic Engineering, Tsinghua National Laboratory for Information Science and Technology, Tsinghua University, Beijing, China
5. Institute for Quantum Computing and Department of Electrical & Computer Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
6. National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada