  Nuclear spins in semiconductors are leading candidates for quantum
technologies, including quantum computation, communication, and sensing.
Nuclear spins in diamond are particularly attractive due to their extremely
long coherence lifetime. With the nitrogen-vacancy (NV) centre, such nuclear
qubits benefit from an auxiliary electronic qubit, which has enabled
entanglement mediated by photonic links. The transport of quantum information
by the electron itself, via controlled transfer to an adjacent centre or via
the dipolar interaction, would enable even faster and smaller processors, but
optical readout of arrays of such nodes presents daunting challenges due to the
required sub-diffraction inter-site distances. Here, we demonstrate the
electrical readout of a basic unit of such systems - a single 14N nuclear spin
coupled to the NV electron. Our results provide the key ingredients for quantum
gate operations and electrical readout of nuclear qubit registers, in a manner
compatible with nanoscale electrode structures. This demonstration is therefore
a milestone towards large-scale diamond quantum devices with semiconductor
scalability.
