Decoherence-protected two qubit quantum gates for spin sensing and control

The ability to sense and control nuclear spins near solid-state defects has potential applications on a wide range of spin-based quantum technologies. In previous work, it was shown that Dynamical Decoupling of the solid state defect combined with direct Radio Frequency (DDRF) control of the nuclear spins creates an effective and selective two-spin interaction that can be used to engineer a two-qubit quantum gate [1]. The DDRF sequence unlocks access to an extended number of nuclear spins compared to more common DD methods, while offering unique design flexibility. In this work, we develop a novel, generalized DDRF framework, incorporating the effect of frequency-detuned RF pulses. Our analytical model, validated against experiment, effectively explains the fundamental limit to gate efficiency, ultimately set by the electron spin coherence. The knowledge gained about this gate type raises important considerations for building the optimal memory register out of a selection of nuclear spins. These results advance our understanding for a broad class of electron-nuclear RF gates and provide a practical toolbox for application-specific design, enabling improved quantum control and sensing.

[1]Bradley, C. E. et al. Phys. Rev. X 9, 031045 (2019)