Coherence of single spins coupled to a nuclear spin bath of varying density

摘要

The dynamics of single electron and nuclear spins in a diamond lattice with different ~(13)C nuclear spin concentration is investigated. It is shown that coherent control of up to three individual nuclei in a dense nuclear spin cluster is feasible. The free-induction decays of nuclear spin Bell states and single nuclear coherences among ~(13)C nuclear spins are compared and analyzed. Reduction in a free-induction-decay time T_2~* and a coherence time T_2 upon increase in nuclear spin concentration has been found. For pure diamond, T_2~* as long as 30 μs and T_2 of up to 0.65 ms for the electron spin has been observed. The ~(13)C concentration dependence of T_2~* is explained by Fermi contact and dipolar interactions with nuclei in the lattice. It has been found that T_2 decreases approximately as 1, where n is ~(13)C concentration, which corresponds to the reported theoretical line of T_2 for an electron spin interacting with a nuclear spin bath.