Hybrid Quantum System with Nitrogen-Vacancy Centers in Diamond Coupled to Surface-Phonon Polaritons in Piezomagnetic Superlattices

In spin-based hybrid quantum systems, the spatial modes of collective spin excitations can be used to encode a register of qubits. However, in superconducting circuits the wavelengths of microwave photons are much larger than the dimensions of the spin ensembles, which complicates direct coupling and limits information processing. This problem could be solved by exploiting the subwavelength nature of surface phonon-polaritons in a piezomagnetic superlattice, via coupling them to an ensemble of N-V spins in diamond. Considering the excellent tenability and scalability of piezoactive superlattices, this approach opens routes to innovative hybrid quantum devices.