Decoherence and dynamical decoupling control of nitrogen-vacancy center   electron spins in nuclear spin baths
  We theoretically study the decoherence and the dynamical decoupling control of nitrogen-vacancy center electron spins in high-purity diamond, where the hyperfine interaction with $^{13}$C nuclear spins is the dominating decoherence mechanism. The decoherence is formulated as the entanglement between the electron spin and the nuclear spins, which is induced by nuclear spin bath evolution conditioned on the electron spin state. The nuclear spin bath evolution is driven by elementary processes such as single spin precession and pairwise flip-flops. The importance of different elementary processes in the decoherence depends on the strength of the external magnetic field. 
Nan Zhao, Sai-Wah Ho and Ren-Bao Liu
cond-mat.mes-hall quant-ph