Spin coherence in two-dimensional materials

Spin defects in semiconducting solids are promising platforms for the realization of quantum bits. At low temperature and in the presence of a large magnetic field, the central spin decoherence is mainly due to the fluctuating magnetic field induced by nuclear spin flip-flop transitions. Using spin Hamiltonians and a cluster expansion method, we investigate the electron spin coherence of defects in two-dimensional (2D) materials, including delta-doped diamond layers, thin Si films, MoS2, and h-BN. We show that isotopic purification is much more effective in 2D than in three-dimensional materials, leading to an exceptionally long spin coherence time of more than 30？ms in an isotopically pure monolayer of MoS2