1. IQIM, California Institute of Technology, Pasadena, CA, USA
2. Department of Physics and Astronomy, University of California, Riverside, CA, USA
3. Station Q Quantum Architectures and Computation Group, Microsoft Research, Redmond, WA 98052, USA
4. Quantum Optics and Laser Science, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom