Sub-nanosecond control for spin-defect quantum memories with a low-cost, compact FPGA platform

Abstract: Dynamical decoupling techniques are widely used to characterize and control the environments of solid-state quantum defects, enabling solid-state quantum memories and nanoscale quantum sensors. However, resolution is often limited by the timing granularity of control hardware, which can undersample narrow spectral features and distort extracted parameters. Here, we demonstrate sub-nanosecond timing control on an inexpensive FPGA-based platform by extending the open-source QICK (Quantum Instrumentation Control Kit) framework using a waveform-offset method. This approach achieves an effective timing resolution of 200~ps on an RF system-on-chip device without modification to the underlying hardware. We apply this capability to dynamical decoupling spectroscopy of nitrogen-vacancy centers in diamond, enabling precise extraction of hyperfine couplings of individual $^{13}\mathrm{C}$ nuclear spins and resolving spectral features that are otherwise undersampled. These results demonstrate that high-resolution, device-level characterization of spin-based quantum memories can be achieved using flexible, inexpensive control hardware, providing a scalable alternative to commercial arbitrary waveform generators.