Steady state preparation of long-lived nuclear spin singlet pair at room temperature

The coherent high-fidelity generation of nuclear spins in long-lived singlet states which may find application as quantum memory or sensor represents a considerable experimental challenge. Here we propose a dissipative scheme that achieves the preparation of pairs of nuclear spins in long-lived singlet states by a protocol that combines the interaction between the nuclei and a periodically reset electron spin of an NV center with local rf-control of the nuclear spins. The final state of this protocol is independent of the initial preparation of the nuclei, is robust to external field fluctuations and can be operated at room temperature. We show that a high fidelity singlet pair of a 13C dimer in a nuclear bath in diamond can be generated under realistic experimental conditions.