Multi-timescale stochastic theory of time-resolved hole-burning in low-temperature ion-doped crystals. Application to laser-dependent dephasing and spectral diffusion in ruby

Recent experiments on time-resolved hole-burning (TRHB) [1-3] and nonexponential photon-echo decays [4,5] in low-temperature ion-doped crystals have demonstrated the multi-timescale dynamics of host nuclei whose spin flips provide the main source of stochastic fluctuations Ut of an impurity ion transition frequency ωab(ωabt=ωab+Ut) leading to optical dephasing and spectral diffusion. Such complicated spin dynamics results from the existence around the impurity ion of the "frozen core" of nuclear spins with their flip rates to be greatly slowed compared to the unperturbed bulk spins.