Diamond nanophotonic structures for quantum spin-photon interfaces

Future quantum networks require end nodes that combine excellent qubit control and coherence with efficient spin-photon interfaces. Optically active spin qubits in diamond represent an auspicious building block. Among these, the group-IV-vacancy qubits are emerging promising candidates: thanks to inversion symmetry these systems are first-order insensitive to charge noise at surfaces, opening the path towards integration in nanophotonic photonic crystal waveguides and cavities.

The fabrication of such nanophotonic devices in diamond itself is challenging, as there is no known wet-processing technique that would allow to fabricate free-hanging structures starting from bulk diamond material.

 

Here, we present our recent results on the realization of all-diamond nanophotonic photonic waveguides and crystal cavities. We demonstrate the fabrication process flow, report on the optical properties of the resulting structures, and show that such structures can be fabricated employing a quasi-isotropic crystal plane dependent reactive-ion-etch.