Important progress in quantum precision measurement: a new method of nanoscale electrical detection based on NV color centers

It is reported that Du Jiangfeng, Shi Kaifa, Wang Ya and others from the Key Laboratory of Micromagnetic Resonance of the Chinese Academy of Sciences have made important progress in the research direction of diamond single-spin quantum precision measurement.

New research results of spectral line resolution based on single-spin paramagnetic resonance

It is reported that the Key Laboratory of Microscopic Magnetic Resonance of the Chinese Academy of Sciences recently proposed and experimentally implemented a high-resolution paramagnetic resonance detection method based on a diamond nitrogen-vacancy (NV) color center quantum sensor, and obtained kilohertz (kHz) spectral line resolution. Single spin paramagnetic resonance spectrum. His research results are titled "Kilohertz electron paramagnetic resonance spectroscopy of single nitrogen centers at zero magnetic field" and published in "Science Advances 6:eaaz8244 (2020)]. Electron paramagnetic resonance spectroscopy technology is an important contemporary material science research method, which is often used to obtain molecular dynamics, structure and other information. One of the main development directions of this technology is to obtain as accurate information as possible from as few samples as possible, which requires both spatial resolution and spectral line resolution to be improved. In recent decades, thanks to the emergence of new detection technologies, the spatial resolution has been continuously improved, and even the detection of a single spin at the nanometer scale has been achieved by paramagnetic resonance. However, subject to the interference of uncontrollable external noise, its spectral line resolution stays at the megahertz (MHz) level, which hinders further analysis of structure, local environment and other information at the single-molecule level. To break through the current limit of spectral line resolution, new methods to overcome environmental noise must be sought. In addition to actively suppressing noise through quantum manipulation, another more direct and effective way is to make the measured spin naturally immune to noise. Under certain conditions such as a magnetic field, there is a special kind of spin states, these spin states can resist the disturbance of external magnetic field noise, and the spectral lines produced by electrons transitioning between these spin states will be narrowed. This physical phenomenon is widely present in systems such as ion traps, nuclear magnetic resonance, and phosphorous silicon. It was previously reported in the literature that for a class of paramagnetic substances, this phenomenon also exists under zero magnetic field. However, the detection sensitivity of traditional paramagnetic resonance technology is related to the size of the magnetic field, and the detection efficiency under zero field is extremely low, which limits practical applications. For this reason, the research team used the NV color center single-spin quantum sensor in diamond (hereinafter referred to as "diamond quantum sensor") for paramagnetic resonance detection. The previous work of Du Jiangfeng’s research team in the laboratory has proved that diamond quantum sensors have the ability to detect single molecules [Fazhan Shi, et al., Science 345, 1135 (2015); Nature Methods 15, 697 (2018)], and its even It still has single-spin detection sensitivity under zero field [Fei Kong, et al., Nature Communications 9, 1563 (2018)]. In order to observe the narrowing of the spectral line and realize high-resolution spectroscopy detection, it is also necessary to eliminate the spectral line broadening caused by the diamond quantum sensor itself. Inspired by the correlation detection in NMR, Du Jiangfeng and others designed a paramagnetic resonance correlation sequence suitable for zero field, which suppressed the intrinsic broadening of the diamond quantum sensor. With this new method, the researchers successfully realized the narrowed transition detection of the electron spin of a single nitrogen atom in diamond in the experiment. Compared with the previous general method, the spectral line resolution was increased by 27 times to 8.6 kHz. This is currently based on diamond. The highest index of microscopic paramagnetic resonance spectroscopy for quantum sensors.

New research results of spectral line resolution based on single-spin paramagnetic resonance

It is reported that the Key Laboratory of Microscopic Magnetic Resonance of the Chinese Academy of Sciences recently proposed and experimentally implemented a high-resolution paramagnetic resonance detection method based on a diamond nitrogen-vacancy (NV) color center quantum sensor, and obtained kilohertz (kHz) spectral line resolution. Single spin paramagnetic resonance spectrum. His research results are titled "Kilohertz electron paramagnetic resonance spectroscopy of single nitrogen centers at zero magnetic field" and published in "Science Advances 6:eaaz8244 (2020)].

Important progress in quantum precision measurement: a new method for nanoscale electrical detection based on NV color centers

It is reported that Du Jiangfeng, Shi Kaifa, Wang Ya and others from the Key Laboratory of Micromagnetic Resonance of the Chinese Academy of Sciences have made important progress in the research direction of diamond single-spin quantum precision measurement. They proposed and experimentally realized a diamond nitrogen-vacancy (NV) color The single spin of the core is the electrical detection method of the quantum sensor (hereinafter referred to as the "diamond quantum sensor"), and the magnetically suppressed NV color center realizes the extraction of the electrical noise information of the diamond near the surface, which is the application of the diamond quantum sensor in the direction of electrical detection. Provide new ways. And the research results were published in the recent "Physics Review Letters" in the form of "Editor's Recommendation" [Nanoscale Electrometry Based on a Magnetic-Field-Resistant Spin Sensor, Phys. Rev. Lett. 124, 247701 (2020)]. The high-resolution and high-sensitivity detection of basic physical quantities such as electricity and magnetism has important applications in the fields of physics, materials, and life sciences. The NV color center in diamond becomes a highly sensitive magnetic quantum sensor due to its superior coherence properties under room temperature atmospheric environment. It has the comprehensive advantages of high sensitivity and high resolution in magnetic detection and imaging. It has been used in single-molecule magnetic resonance and Nanoscale magnetic imaging and other fields [Representative papers by Jiangfeng Du’s team in this direction: Nature Physics 10, 21 (2014); Science 347, 1135 (2015); Nature Methods 15, 697 (2018); Science Advances 5, eaau8038 (2019) ); Science Advances 6, eaaz8244 (2020)]. At the same time, the NV color center was proposed as an electrical signal quantum sensor as early as 2011 [Nat. Phys. 7, 459 (2011)], and it has been proven to have the detection sensitivity of a single charge in an atmosphere at room temperature. Charge and electric field detection. But the NV color center as a quantum sensor, the practical goal is to apply it to the signal characterization of diamond in vitro. In order to use the NV color center for the high-sensitivity and high-resolution characterization of the electrical signal of diamond in vitro samples, it needs to be prepared at the shallow diamond surface at a depth of 10 nanometers to several tens of nanometers. However, the magnetic noise environment near the diamond surface is complicated, and the NV color center is susceptible to magnetic signal interference, which limits its practical application to electric field detection.

New research results of spectral line resolution based on single-spin paramagnetic resonance

It is reported that the Key Laboratory of Microscopic Magnetic Resonance of the Chinese Academy of Sciences recently proposed and experimentally implemented a high-resolution paramagnetic resonance detection method based on a diamond nitrogen-vacancy (NV) color center quantum sensor, and obtained kilohertz (kHz) spectral line resolution. Single spin paramagnetic resonance spectrum. His research results are titled "Kilohertz electron paramagnetic resonance spectroscopy of single nitrogen centers at zero magnetic field" and published in "Science Advances 6:eaaz8244 (2020)]. Electron paramagnetic resonance spectroscopy technology is an important contemporary material science research method, which is often used to obtain molecular dynamics, structure and other information. One of the main development directions of this technology is to obtain as accurate information as possible from as few samples as possible, which requires both spatial resolution and spectral line resolution to be improved. In recent decades, thanks to the emergence of new detection technologies, the spatial resolution has been continuously improved, and even the detection of a single spin at the nanometer scale has been achieved by paramagnetic resonance. However, subject to the interference of uncontrollable external noise, its spectral line resolution stays at the megahertz (MHz) level, which hinders further analysis of structure, local environment and other information at the single-molecule level. To break through the current limit of spectral line resolution, new methods to overcome environmental noise must be sought. In addition to actively suppressing noise through quantum manipulation, another more direct and effective way is to make the measured spin naturally immune to noise. Under certain conditions such as a magnetic field, there is a special kind of spin states, these spin states can resist the disturbance of external magnetic field noise, and the spectral lines produced by electrons transitioning between these spin states will be narrowed. This physical phenomenon is widely present in systems such as ion traps, nuclear magnetic resonance, and phosphorous silicon. It was previously reported in the literature that for a class of paramagnetic substances, this phenomenon also exists under zero magnetic field. However, the detection sensitivity of traditional paramagnetic resonance technology is related to the size of the magnetic field, and the detection efficiency under zero field is extremely low, which limits practical applications. For this reason, the research team used the NV color center single-spin quantum sensor in diamond (hereinafter referred to as "diamond quantum sensor") for paramagnetic resonance detection. The previous work of Du Jiangfeng’s research team in the laboratory has proved that diamond quantum sensors have the ability to detect single molecules [Fazhan Shi, et al., Science 345, 1135 (2015); Nature Methods 15, 697 (2018)], and its even It still has single-spin detection sensitivity under zero field [Fei Kong, et al., Nature Communications 9, 1563 (2018)]. In order to observe the narrowing of the spectral line and realize high-resolution spectroscopy detection, it is also necessary to eliminate the spectral line broadening caused by the diamond quantum sensor itself. Inspired by the correlation detection in NMR, Du Jiangfeng and others designed a paramagnetic resonance correlation sequence suitable for zero field, which suppressed the intrinsic broadening of the diamond quantum sensor. With this new method, the researchers successfully realized the narrowed transition detection of the electron spin of a single nitrogen atom in diamond in the experiment. Compared with the previous general method, the spectral line resolution was increased by 27 times to 8.6 kHz. This is currently based on diamond. The highest index of microscopic paramagnetic resonance spectroscopy for quantum sensors.