  Quantum processors based on color centers in diamond are promising candidates
for future large-scale quantum computers thanks to their flexible optical
interface, (relatively) high operating temperature, and high-fidelity
operation. Similar to other quantum-computing platforms, the electrical
interface required to control and read out such qubits may limit both the
performance of the whole system and its scalability. To address this challenge,
this work analyzes the requirements of the electrical interface and
investigates how to efficiently implement the electronic controller in a
scalable architecture comprising a large number of identical unit cells. Among
the different discussed functionalities, a specific focus is devoted to the
generation of the static and dynamic magnetic fields driving the electron and
nuclear spins, because of their major impact on fidelity and scalability.
Following the derived requirements, different system architectures, such as a
qubit frequency-multiplexing scheme, are considered to identify the most power
efficient approach, especially in the presence of inhomogeneity of the qubit
Larmor frequency across the processor. As a result, a
non-frequency-multiplexed, 1-mm$^2$ unit-cell architecture is proposed as the
optimal solution, able to address up to one electron-spin qubit and 9
nuclear-spin qubits within a 3-mW average power consumption, thus establishing
the baseline for the scalable electrical interface for future large-scale
color-center quantum computers.
