University of Science and Technology of China: Researchers Realize Coherent Manipulation of Single-spin Qubits in Silicon Carbide at Room Temperature

Prof. LI Chuanfeng, Prof. XU Jinshi and their colleagues from Prof. GUO Guangcan’s group at University of Science and Technology of China, collaborating with Prof. Adam Gali from the Wigner Research Centre for Physics, Hungary, realized the high-contrast readout and coherent manipulation of a single silicon carbide divacancy color center electron spin at room temperature for the first time. The study was published in National Science Review on July 5.

Solid-state spin color centers are of great importance to the application of quantum technologies, especially the nitrogen-vacancy (NV) centers in diamond. Since the detection of individual NV defect centers in diamond with room temperature was reported in 1997, the NV centers in diamond have been applied to versatile fields including quantum computing, quantum networking and quantum sensing.

The researchers have been seeking similar color centers in other semiconductor materials using more mature material processing and device integration technologies. Among them, the spin color centers in silicon carbide, including silicon vacancies (missing a silicon atom) and divacancies (missing a silicon atom and an adjacent carbon atom), have attracted interest due to excellent optical and spin properties.

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

The researchers implanted defect color centers in SiC with their ion implantation technique (ACS Photonics and Phys. Rev. Lett.) 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 (ODMR), and found that one type of divacancy color centers whose single-photon emission rate is up to 150 kilo counts per second has a 30% spin readout contrast.

These two important parameters showed an order of magnitude higher than those of the silicon vacancy color center in SiC. For the first time, the spin color centers of SiC showed excellent properties comparable to the diamond NV color center at room temperature. Especially, the coherence time of the electron spin at room temperature was extended to 23 microseconds, and the coupling and detection of a single electron spin and a nearby nuclear spin in SiC color centers were realized.

This study lays the foundations for building room temperature solid-state quantum storage and scalable solid-state quantum networks which are based on the SiC spin color center system. It is essential for the next generation of hybrid quantum devices to integrate spin defects with a high readout contrast and a high photon count rate into high-performance SiC electron devices.