  Color centers in diamonds have emerged as a leading solid-state platform for
advancing quantum technologies, satisfying the DiVincenzo criteria and recently
achieving a quantum advantage in secret key distribution. Recent theoretical
works estimate that general-purpose quantum computing using local quantum
communication networks will require millions of physical qubits to encode
thousands of logical qubits, which presents a substantial challenge to the
hardware architecture at this scale. To address the unanswered scaling problem,
in this work, we first introduce a scalable hardware modular architecture
"Quantum System-on-Chip" (QSoC) that features compact two-dimensional arrays
"quantum microchiplets" (QMCs) containing tin-vacancy (SnV-) spin qubits
integrated on a cryogenic application-specific integrated circuit (ASIC). We
demonstrate crucial architectural subcomponents, including (1) QSoC fabrication
via a lock-and-release method for large-scale heterogeneous integration; (2) a
high-throughput calibration of the QSoC for spin qubit spectral inhomogenous
registration; (3) spin qubit spectral tuning functionality for inhomogenous
compensation; (4) efficient spin-state preparation and measurement for improved
spin and optical properties. QSoC architecture supports full connectivity for
quantum memory arrays in a set of different resonant frequencies and offers the
possibility for further scaling the number of solid-state physical qubits via
larger and denser QMC arrays and optical frequency multiplexing networking.
