Nitrogen-vacant color center RF signal quantum sensing in silicon carbide systems

On 17 May 2023, the research team of Professor Xiaogang Liu of the National University of Singapore and Professor Weibo Gao of Nanyang Technological University published a new study entitled “Quantum sensing of radio-frequency signal with NV centers in SiC” in Science Advances.

In this study, the coherence time of the nitrogen-vacant color center (NV center) in the silicon carbide system is extended, and the quantum sensing of the artificial AC field (center frequency is about 900 kHz) at room temperature is realized with a spectral resolution of 10 kHz. At the same time, synchronous readout technology is used to further increase the frequency resolution of the sensor to 0.01 kHz. These achievements have laid the foundation for silicon carbide quantum sensors to move towards the application of low-cost nuclear magnetic resonance (NMR) spectrometers.

The corresponding authors of the paper are Professor Liu Xiaogang and Gao Weibo, and the first author is Jiang Zhengzhi.

Quantum sensing technology, with its unique ability to exploit quantum mechanical properties, such as quantum entanglement and quantum interference, has demonstrated its potential to surpass classical sensors in improving sensing accuracy and sensitivity. It has huge applications in the biomedical field and geophysical fields, including mineral exploration and seismology, covering microscopy, positioning systems, communication technology and electromagnetic field sensors. In addition, quantum sensing technology is unique in detecting weak RF signals, which has far-reaching implications for military and security applications.

However, to achieve efficient quantum sensing, some technical challenges need to be overcome, such as the preparation, manipulation, and readout of quantum states, as well as decoherence caused by the interaction between quantum systems and the environment. In this context, the unique advantages of silicon carbide began to be highlighted, it can be compatible with conventional electronic circuits, and has mature industrial-scale production and doping technology.

Recently, a research team led by Professor Xiaogang Liu of the National University of Singapore and Professor Weibo Gao of Nanyang Technological University proposed an innovative method for quantum sensing using nitrogen-vacancy (NV) color centers in silicon carbide, so that weak radio frequency (RF) signals can be detected at room temperature. The research team first studied in detail the key parameters such as zero phonon line (ZPL), coherence time, relaxation time and other key parameters of NV color center in silicon carbide, and compared these characteristics with the corresponding characteristics of NV color center in diamond. They found that the ZPL of the NV color center in silicon carbide is located in the near-infrared range and has a good match with the optical fiber communication band. Although the coherence time of NV centroids in silicon carbide is affected by nuclear spin baths and electronic noise, the coherence time can be significantly improved by using dynamic decoupling techniques.

By introducing dynamic decoupling technology (XY8-N pulse train), they succeeded in extending the coherence time of the NV color center in silicon carbide by a factor of 10 to 28.1 microseconds. Immediately afterwards, they used correlation spectroscopy to achieve a spectral resolution of 10 kHz at a frequency of about 900 kHz. The research team further adopted synchronous readout technology, which greatly improved the spectral resolution, increasing by a factor of 1000 to a staggering 0.01 kHz.

Figure 1: Experimental setup and silicon carbide structure.

Figure 2: Measurement of spin characteristics.

Figure 3: Dynamic decoupling measurements.

Figure 4: Correlation spectral measurements.

Figure 5: Simultaneous readout technology.

This discovery provides new possibilities in the field of quantum sensing, especially in the precise detection of radio frequency signals, which has great potential value in the military and security fields. At the same time, the research team’s method also opens up a new path for silicon carbide as a quantum sensing platform. (Source: Science Network)

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