Coherent storage of photoexcited triplet states using 29Si nuclear spins   in silicon
  Pulsed electron paramagnetic resonance spectroscopy of the photoexcited, metastable triplet state of the oxygen-vacancy center in silicon reveals that the lifetime of the ms = \pm1 sub-levels differ significantly from that of the ms =0 state. We exploit this significant difference in decay rates to the ground singlet state to achieve nearly ~100% electron spin polarization within the triplet. We further demonstrate the transfer of a coherent state of the triplet electron spin to, and from, a hyperfine-coupled, nearest-neighbor 29Si nuclear spin. We measure the coherence time of the 29 Si nuclear spin employed in this operation and find it to be unaffected by the presence of the triplet electron spin and equal to the bulk value measured by nuclear magnetic resonance. 
Waseem Akhtar, Vasileia Filidou, Takeharu Sekiguchi, Erika Kawakami,   Tatsumasa Itahashi, Leonid Vlasenko, John J. L. Morto...
cond-mat.other cond-mat.mtrl-sci