  Controlled fabrication and identification of bright single photon emitters is
at the heart of quantum optics and materials science. Here we demonstrate a
controlled engineering of a chromium bright single photon source in bulk
diamond by ion implantation. The Cr center has fully polarized emission with a
ZPL centered at 749 nm, FWHM of 4 nm, an extremely short lifetime of ~1 ns, and
a count rate of 500 kcounts/s. By combining the polarization measurements and
the vibronic spectra, a model of the center has been proposed consisting of one
interstitial chromium atom with a transition dipole along one of the <100>
directions.
