Robust Spin Polarization by Adiabatic Dynamical Decoupling

Abstract: High-fidelity multi-qubit initialization is vital for quantum simulation, quantum information processing (QIP), and quantum sensing. In diamond platforms, nuclear spin registers can be initialized through polarization transfer from a nearby electronic spin whose high gyromagnetic ratio enables efficient dynamical nuclear polarization (DNP). These hybrid systems are typically controlled using diabatic spin rotations, which require precise knowledge of all system parameters. Adiabatic DNP protocols on the other hand have less strict requirements and could enable robust and high fidelity spin transfer. However, due to the slow adiabatic sweeps and limited electron spin coherence times, this approach has remained inaccessible. Here, we demonstrate adiabatic pulsed nuclear spin polarization at room temperature in diamond. We achieve enhanced polarization efficiency, a broad resonance window, and improved tolerance to hyperfine coupling uncertainties relative to conventional diabatic pulsed protocols. We also show how this approach can benefit the initialization of spin clusters. These results set the scene for enhanced qubit initialization in solid state through adiabatic pulsed driving, with applications in solid-state quantum sensor and quantum memory technologies.