Single-Spin Color Centers in SiC Cue Up Potential for Quantum Storage Advances

A group at the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS) achieved the high-contrast readout and coherent manipulation of a single silicon carbide divacancy color center electron spin at room temperature. The researchers said their advancement marks a breakthrough that had not been previously achieved.

Solid-state spin color centers influence many quantum technology applications. These include the nitrogen-vacancy (NV) center in diamond; these centers have been applied to quantum computing, quantum networking, and quantum sensing.

To take advantage of more mature materials processing and device integration technologies, researchers now seek similar color centers in other semiconductor materials. The spin color centers in silicon carbide (SiC), including silicon vacancies (missing a silicon atom) and divacancies (missing a silicon atom and an adjacent carbon atom), have attracted broad interest due to their optical and spin properties.

However, the typical readout contrast via room-temperature coherent manipulation of the single silicon vacancy color centers is only 2%. The photon count rate is also as low as 10 kilo counts per second (kcps). These shortages restrict the practical application of the coherent manipulation of the single silicon vacancy color centers at room temperature.

The USTC researchers implanted defect color centers in SiC, using its ion implantation technique to manufacture a divacancy color center array. They achieved spin-coherent manipulation of the single divacancy color center at room temperature with the optically detected magnetic resonance. One type of divacancy color centers (PL6) had a 30% spin readout contrast. Its single-photon emission rate was up — to 150 kcps.

With this divacancy, the spin color centers of SiC was of comparable in quality to the diamond NV color center at room temperature. The coherence time of the electron spin at room temperature was extended to 23 µs.

Moreover, the research team also realized the coupling and detection of a single electron spin and a nearby nuclear spin in SiC color centers.

The researchers said the work lays a foundation for room-temperature solid-state quantum storage and scalable solid-state quantum networks, both of which are based on the SiC spin color center system.

The research was published in National Science Review (China) (www.doi.org/10.1093/nsr/nwab122).