Furthermore, V Si-related defects in SiC can be integrated with existing optoelectronic devices 21 and, in contrast to GaAs-based quantum dots 22, operate even at room temperature.
Similarly, scattering losses at interfaces and signal attenuation in optical fibers decrease with wavelength as well. Rayleigh scattering losses in photonic structures are inversely proportional to the fourth power of the wavelength 17, 18, giving almost one order of magnitude lower losses for these defects compared with the nitrogen-vacancy defect in diamond ( λ ZPL=637 nm) 19 or the carbon antisite-vacancy pair in SiC ( λ ZPL=660 nm) 20. In particular, the zero-phonon lines (ZPLs) of V Si-related defects in 4H and 6H polytypes of SiC present spectrally narrow features at near-infrared (NIR) wavelengths ( λ ZPL=850–1,200 nm) 10, 14, 15, 16. Silicon vacancy ( V Si)-related defects in SiC have some advantages compared with other solid-state single-photon emitters. Until recently, however, the engineering of such spin centres in SiC on the single-emitter level has remained elusive 13. More recently, ensemble emitters with spin dephasing times in the order of microseconds and room-temperature optically detectable magnetic resonance (ODMR) have been identified in silicon carbide (SiC) 10, 11, 12, a compound being highly compatible to up-to-date semiconductor device technology. Such single quantum systems have been realized using quantum dots 6, colour centres in diamond 7, dopants in nanostructures 8 and molecules 9. For many of these applications it is necessary to have control over single emitters with long spin coherence times.
Quantum emitters hosted in crystalline lattices are highly attractive candidates for quantum information processing 1, secure networks 2, 3 and nanosensing 4, 5. The on-demand engineering of optically active spins in technologically friendly materials is a crucial step toward implementation of both maser amplifiers, requiring high-density spin ensembles, and qubits based on single spins. The vacancy spins can be manipulated using an optically detected magnetic resonance technique, and we determine the transition rates and absorption cross-section, describing the intensity-dependent photophysics of these emitters. An isolated silicon vacancy serves as a near-infrared photostable single-photon emitter, operating even at room temperature. Here, silicon vacancies are generated in a nuclear reactor and their density is controlled over eight orders of magnitude within an accuracy down to a single vacancy level. These atomic-scale defects can be created using electron or neutron irradiation however, their precise engineering has not been demonstrated yet. Vacancy-related centres in silicon carbide are attracting growing attention because of their appealing optical and spin properties.