1. Department of Physics, Harvard University, Cambridge, MA 02138, USA.
2. Russian Quantum Center, Skolkovo, Moscow 143025, Russia.
3. P. N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow 119991, Russia.
4. John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
5. Sandia National Laboratories, Albuquerque, NM 87185, USA.
6. Institute for Quantum Optics, University of Ulm, 89081 Ulm, Germany.
7. Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.