Imaging and edge detection have been widely applied and played an important role in security checking and medical diagnosis. However, as we know, most edge detection based on ghost imaging system requires large measurement times and the target object image cannot be provided directly. In this work, a new edge detection based on joint iteration of projected Landweber iteration regularization and guided filter ghost imaging method has been proposed, which can improve the feature detection quality in ghost imaging. This method can also achieve high-quality imaging. Simulation and experiment results show that the spatial information and edge information of target object are successfully recovered from the random speckle patterns without special coding under a low measurement times, and the edge image quality is improved remarkably. This approach improves the the applicability of ghost imaging and can satisfy the practical application fields of imaging and edge detection at the same time.

Most studies on ghost imaging focus on high-quality and high-resolution imaging with a few measurements. However, as far as we know, continuous multi-resolution imaging is rarely mentioned. In this work, we both theoretically and experimentally demonstrate a method that uses the Hadamard derived pattern to realize continuous multi-resolution imaging simply and quickly, which we call multi-resolution progressive computational ghost imaging, whereby both the reconstruction time and measurements required for multi-resolution images can be significantly reduced. This approach improves the flexibility of ghost imaging, and can be extended to multi-resolution image-dependent practical applications, such as target tracking and recognition.

Traditional video conference systems depend largely on computational complexity to ensure system security, but with the development of high-performance computers, the existing encryption system will be seriously threatened. To solve this problem, a hybrid encryption scheme for quantum secure video conferencing combined with blockchain is proposed in this study. In the system solution architecture, first, the quantum key distribution network is embedded in the classic network; then, the “classical + quantum” hybrid encryption scheme is designed according to the secret level required for the video conference content. Besides, the real-time monitoring module of the quantum key distribution network is designed to ensure that users can check the running state of the network at any time. Meeting minutes can be shared by combining with blockchain. In order to quickly query meeting minutes, a cache-efficient query method based on B+ tree is proposed. The experimental results show that compared with the traditional video conference system, the quantum secure video conference system sufficiently integrates the technical advantages of the quantum key distribution to resist the security threats such as channel eavesdropping and high-performance computational attacks while ensuring the stable operation of the classic system, thus providing a video conference system with a higher security level. Meanwhile, the query time cost of blockchain with different lengths is tested, and the query efficiency of the proposed method is 3.15-times higher than the original query efficiency of blockchain.

We theoretically propose a scheme to realize rotation sensing based on two coupled whispering-gallery-mode resonators with loss and gain. We consider that the active resonator with gain is rotated while the passive one with loss is stationary. The rotation will induce Sagnac effect and we show that the eigenfrequencies of the supermodes are sensitive to the Sagnac-Fizeau shift. Therefore, we can measure the average photon number in the steady state or the fluctuation spectrum of the output fields to detect the angular velocity of the rotation. We hope that our investigation will be useful in the design of a quantum gyroscope based on spinning resonators.

The multi-sensor system based on single pixel imaging can realize the simultaneous measurement and imaging of various optical information (such as spectrum, polarization, etc.), in which a single pixel sensor can measure one kind of optical information. Spectral imaging technology can simultaneously obtain rich information such as spatial structure and fine spectral characteristics of the target scene. The architecture and implementation of most spectral imaging systems are complex, which limits or affects their indicators, parameters, and applications to varying degrees. Here, we propose a novel multispectral single pixel imaging method based on spatial and spectral dimension decoupling. This method uses spatial dimension compression coding modulation, and spectral dimension modulation through ingenious optical system design. It utilizes a single pixel detector array combined with traditional spectral filtering technology to directly and parallel collect spatial image compression coding information from various spectral channels. This method reduces the information carrying capacity of a single photon and reduces the requirements for detection signal to noise ratio. The experiment demonstrated 15 channels of visible and near-infrared spectral single pixel imaging and demonstrated real-time multispectral single pixel imaging with an imaging speed of 5 Hz, which can be extended to spectral imaging with higher spectral resolution and more spectral channels. This work can facilitate the use of multi-sensor arrays for more convenient research such as spectral information acquisition.