When the sampling data of ghost imaging are recorded with less bits, i.e., experiencing quantization, a decline in image quality is observed. The fewer bits that are used, the worse the image one gets. Dithering, which adds suitable random noise to the raw data before quantization, is proved to be capable of compensating image quality decline effectively, even for the extreme binary sampling case. A brief explanation and parameter optimization of dithering are given.
Abstract. When use the image mutual information to assess the quality of reconstructed image in pseudo-thermal light ghost imaging, a negative exponential behavior with respect to the measurement number is observed. Based on information theory and a few simple and verifiable assumptions, semiquantitative model of image mutual information under varying measurement numbers is established. It is the Gaussian characteristics of the bucket detector output probability distribution that leads to this negative exponential behavior. Designed experiments verify the model.
Unmanned Aerial Vehicles (UAVs) can cooperate through formations to perform tasks. Wireless communication allows UAVs to exchange information, but for the situations requiring high security, electromagnetic silence is needed to avoid potential threats. The passive UAV formation maintenance strategies can fulfill the requirement of electromagnetic silence at the cost of heavy real-time computing and precise locations of UAVs. To pursue high real-time performance without the localization of UAVs, this paper proposes a scalable distributed control algorithm for bearing-only passive UAV formation maintenance. By minimizing necessary communication, pure angle information is applied to maintain UAV formations through distributed control, without the knowledge of the UAVs’ precise locations. The convergency of the proposed algorithm is proven strictly and the converging radius is derived. Through simulation, the proposed algorithm is proven to be suitable for a general case and demonstrates fast convergence speed, strong anti-interference capability, and high scalability.
In this letter, sensitivity analysis is adopted to interpret why correspondence ghost imaging can restore better images with fewer reference patterns which have larger bucket value fluctuation: these selected patterns are more alike with regard to the target to be restored. The contribution of reference patterns to imaging can be quantified as sensitivity coefficients. In addition, the peak signal-to-noise ratio and mean square error are calculated to compare the restored image quality, and results confirmed that sensitivity coefficients are more robust than bucket value fluctuation in the presence of noise for selecting reference patterns.
Quantum resources,such as discord and entanglement, are crucial in quantum information processing. In this paper, quantum resources are studied from the aspect of quantum state superposition. We define the local superposition (LS) as the superposition between basis of single part, and nonlocal superposition (NLS) as the superposition between product basis of multiple parts. For quantum resource with nonzero LS, quantum operation must be introduced to prepare it, and for quantum resource with nonzero NLS, nonlocal quantum operation must be introduced to prepare it. We prove that LS vanishes if and only if the state is classical and NLS vanishes if and only if the state is separable. From this superposition aspect, quantum resources are categorized as superpositions existing in different parts. These results are helpful to study quantum resources from a unified frame. PACS numbers: 03.67.-a, 03.67.Mn,03.65.Ta
II. LOCAL SUPERPOSITION IN BIPARTITE SYSTEMWhen considering a quantum state with superposition in the {|0 , |1 } basis, |ψ = α |0 + β |1 , the coherence of the state can be defined as C({|0 , |1 }) = 2 |α| |β| =
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