In this letter, we demonstrate an approach for the measurement of microwave electric field intensity based on Rydberg electromagnetically induced transparency (EIT)– Autler Townes (AT) splitting effect using a cesium vapor MEMS cell. The atomic absorption characteristics at different pump powers were obtained experimentally, which proved the feasibility of fabricated cesium vapor MEMS cell. The dependence of EIT-AT splitting separations on the microwave electric field intensities at 23.887 GHz was investigated at room temperature, and the minimum microwave electric field was measured to be 2 V/m. This approach indicates that the prepared cesium vapor MEMS cell can be qualified for microwave electric field intensity measurement, and has tremendous potential for the development of integrating quantum microwave field intensity meters.

The wide-field (2.42 mm × 1.36 mm, resolution: 5.04 µm) tomography imaging of double circuits is performed using nitrogen-vacancy (NV) center ensembles in a diamond. The magnetic-field distribution on the surface of the circuit produced by the lower layer is obtained. Vector magnetic superposition is used to separate the magnetic-field distribution produced by the lower layer from the magnetic-field distribution produced by two layers. An inversion model is used to perform the tomography imaging of the magnetic-field distribution on the lower layer surface. Compared with the measurements of the upper layer, the difference in the maximum magnetic-field intensity of inversion is approximately 0.4%, and the difference in the magnetic-field distribution of inversion is approximately 8%, where the depth of the lower layer is 0.32 mm. Simulations are conducted to prove the reliability of the imaging. These results provide a simple and highly accurate reference for the detection and fault diagnosis of multilayer and integrated circuits.

Quantum magnetic sensing technology utilizing diamond nitrogen vacancy (NV) color centers exhibits high spatial resolution, sensitivity, and dynamic range. The practical applications of the NV color centers magnetometer are limited by its complex system and large volume. To expand the range of applications, it is necessary to improve the integration level of NV color centers magnetometer while meeting the requirements of high portability and sensitivity. In this article, we designed a portable integrated NV magnetometer and utilized the continuous wave optically detected magnetic resonance (CW-ODMR) method to detect magnetic field. We coupled a micro self-focusing lens with a fiber to create a fiber self-focusing integrated module (FSFI) and bonded a diamond to the other end of the lens. This module was applied to the integrated NV magnetometer. This arrangement ensured uniform intensity of the laser and expanded the irradiation area on the diamond, thereby improving the excitation efficiency of the NV color centers and the number of NV color centers involved in sensing. The magnetometer integrated a microwave antenna module and a fluorescence collection and processing module. The magnetometer was packaged using 3-D printing technology and occupied a volume of 10 cm3. After conducting experimental tests, the sensitivity of the magnetometer was 9.6 nT/Hz1/2, and the photon shot noise limited sensitivity can reach 0.85 nT/Hz1/2. The maximum detection relative error of the dc magnetic field was 0.848%, and the detection bandwidth was 40 Hz. The signal-to-noise ratio (SNR) of the ac magnetic field was 28.107 dB within the detectable bandwidth. The integrated NV magnetometer exhibits excellent performance in detecting magnetic fields and offers strong portability. In various fields, including magnetic anomaly localization, battery current detection, and medical diagnosis, it possesses significant potential for application.

Invisible microstrip defect detection is of great significance for ensuring the reliability of integrated circuits and improving the performance of communication system. In this article, the microwave fields radiated by six typically invisible microstrip defects were experimentally characterized with high accuracy based on quantum wide-field microscope, and the origin of microwave field contrast was theoretically analyzed. In a view of 1400 $\times$ 700 $\mu$ m $^{2}$ , the microwave near-field distribution radiated by invisible microstrip defects was reconstructed with a resolution of 1.63 $\mu$ m/pixel, and the microwave magnetic field detection sensitivity reached 0.7 nT/Hz $^{\mathrm{1/2}}$ . Meanwhile, the causes of microwave field discrepancies were analyzed specifically on the basis of microstrip transmission line theory. It was attributed to the transmission loss and the uneven distribution of induced current arising from variations in geometrical structures. The phenomenon validated the feasibility of detecting invisible microstrip defects utilizing the microwave field intensity distribution. The proposed approach is expected to have applications in microchip design and radio frequency (RF) equipment maintenance, thereby notably improving the practicability of quantum measurement technology.

Measurement of radio frequency chip microwave field is of great importance for the manufacture of precision instruments and the development of integrated circuits. In this paper, the characterization of chip surface three-dimensional (3D) microwave field distribution was realized with high-resolution based on diamond nitrogen-vacancy (NV) centers, and the field-image separation technique was developed to suppress the stray light noise caused by the reflection of the chip. The feasibility of the proposed method was verified by characterizing the planar microwave fields at different powers and the 3D microwave fields at different frequencies radiated by an antenna chip with a characteristic linewidth of 100 μm. The microwave field of chip radiation was accurately reconstructed with a vertical resolution of 30 μm, and the optimal NV detection sensitivity is 0.8 nT/Hz ^1/2 . The results provide a new approach for antenna radiation detection and on-chip measurement based on quantum detection techniques.

Imaging of electronic device surface or sub-surface electromagnetic fields under operating conditions is important for device design and diagnosis. In this study, we proposed a method to characterize specific magnetic field properties of electromagnetic devices at micron-scale using a solid-state quantum sensor, namely diamond nitrogen-vacancy (NV) centers. By employing a wide-field magnetic field measurement technique based on NV centers, we rapidly obtain the first-order magnetic field distribution of anomalous regions. Furthermore, we approximate the second-order magnetic field (magnetic gradient tensor) using the differential gradient method. To visualize the electromagnetic anomalous regions boundary, we utilize the tensor invariants of the magnetic gradient tensor components, along with their nonlinear combinations. The identification error rate of the anomalous regions is within 12.5%. Additionally, the electromagnetic field of anomalous regions is simulated showing the measurement accuracy. Our study shows that the experimental results are very similar to the theoretical simulation of the electromagnetic field (error: 7%). This work is essential for advancing electromagnetic field characterization of electronic devices and the advancement of quantum magnetic sensor applications.