1. Joint Research Center for Atom Technology (JRCAT)-Angstrom Technology Partnership (ATP), 1-1-4 Higashi, Tsukuba, Ibaraki 305-0046, Japan, Hamamatsu Photonics K. K., Tsukuba Research Laboratory, 5-9-2 Tokodai, Tsukuba, Ibaraki 300-2635, Japan, and Institute of Applied Physics, University of Tsukuba, 1-1-1 Ten-nodai Tsukuba, Ibaraki 305-0006, Japan