The de Leon lab engineers nitrogen-vacancy and other color centers in diamond and wide-bandgap materials as solid-state quantum sensors and qubits, spanning materials growth and surface chemistry, nanophotonic integration, and magnetic-field/thermal sensing of quantum materials, alongside a parallel effort on superconducting qubit noise and loss. This builds on the broader tradition of ensemble NV magnetometry (DEER, NMR, T1 relaxometry) that has reached pT/sqrt(Hz)-class sensitivities, which de Leon's group extends toward single- and few-spin scanning-probe magnetometry of correlated electron materials.