Shallow implanted SiC spin qubits used for sensing an internal spin bath and external YIG spins

Silicon vacancy (VSi) color centers in bulk SiC are excellent electron spin qubits. However, most spin based quantum devices require shallow spin qubits, whose dynamics is often different from that of bulk ones. Here, we demonstrate (i) a new method for creating shallow VSi (V2) spin qubits below the SiC surface by low energy ion implantation through a sacrificial SiO₂ layer, (ii) that these shallow VSi are dipolar coupled to an electronic spin bath, analysed by Hahn echo decay, dynamical decoupling (DD), and optically pumped pulsed electron-electron double resonance experiments (OP-PELDOR), (iii) that their coherence time increases with cooling of the spin bath (from 55 μs at 297 K to 107 μs at 28 K), and that it can be further extended to 220 μs at 100 K by DD, thus demonstrating their relevance for PELDOR-based quantum sensors and processors. Finally, (iv) external spin sensing is demonstrated by the shift of VSi magnetic resonance lines induced by the dipolar stray magnetic field of a nearby ferrimagnetic YIG film.