  Solid-state quantum registers are exceptional for storing quantum information
at room temperature with long coherence time. Nevertheless, practical
applications toward quantum supremacy require even longer coherence time to
allow for more complex algorithms. In this work we propose a quantum register
that lies in a decoherence-free subspace to be implemented with color centers
in diamond. The quantum information is encoded in two logical states composed
of two nearby nuclear spins, while an electron spin is used as ancilla for
initialization and control. Moreover, by tuning an off-axis magnetic field we
enable non-nuclear-spin-preserving transitions that we use for preparing the
register through Stimulating Raman Adiabatic Passage. Furthermore, we use this
sequence to manipulate the quantum register and an individual nuclear spin.
