- 标题
- 摘要
- 关键词
- 实验方案
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Extreme nonlinear dynamics in vacuum laser acceleration with a crossed beam configuration
摘要： A relatively simple model problem where a single electron moves in two relativistically strong obliquely intersecting plane wave-packets is studied using a number of different numerical solvers. It is shown that, in general, even the most advanced solvers are unable to obtain converged solutions for more than about 100 fs in contrast to the single plane wave problem, and that some basic metrics of the orbit show enormous sensitivity to the initial conditions. At a bare minimum, this indicates an unusual degree of nonlinearity, and may well indicate that the dynamics of this system are chaotic.
关键词： crossed beam configuration,vacuum laser acceleration,nonlinear dynamics,relativistic electron motion,chaotic dynamics
更新于2025-09-16 10:30:52
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Cross-predicting the dynamics of an optically injected single-mode semiconductor laser using reservoir computing
摘要： In real-world dynamical systems, technical limitations may prevent complete access to their dynamical variables. Such a lack of information may cause significant problems, especially when monitoring or controlling the dynamics of the system is required or when decisions need to be taken based on the dynamical state of the system. Cross-predicting the missing data is, therefore, of considerable interest. Here, we use a machine learning algorithm based on reservoir computing to perform cross-prediction of unknown variables of a chaotic dynamical laser system. In particular, we chose a realistic model of an optically injected single-mode semiconductor laser. While the intensity of the laser can often be acquired easily, measuring the phase of the electric field and the carriers in real time, although possible, requires a more demanding experimental scheme. We demonstrate that the dynamics of two of the three dynamical variables describing the state of the laser can be reconstructed accurately from the knowledge of only one variable, if our algorithm has been trained beforehand with all three variables for a limited period of time. We analyze the accuracy of the method depending on the parameters of the laser system and the reservoir. Finally, we test the robustness of the cross-prediction method when adding noise to the time series. The suggested reservoir computing state observer might be used in many applications, including reconstructing time series, recovering lost time series data and testing data encryption security in cryptography based on chaotic synchronization of lasers.
关键词： reservoir computing,chaotic dynamics,cross-prediction,machine learning,semiconductor laser
更新于2025-09-16 10:30:52
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On symmetric color image encryption system with permutation-diffusion simultaneous operation
摘要： In the traditional image encryption systems, the permutation-di?usion operation is often conducted in two essentially separable or independent steps, which appears not only to be ine?cient but also vulnerable in being attacked since each step can be targeted separately. In this paper, we propose a new plaintext-related cryptosystem in which the permutation-di?usion operation is performed in a simultaneous manner. More speci?cally, the simultaneous permutation-di?usion operation (PDSO) leads to the confusion and di?usion interacted each other, and thus generates better security level as well as higher e?ciency of encryption process. The proposed encryption scheme only requires a single PDSO in the corresponding encryption process, in which the ?rst encrypted pixel’s position in cipher image is randomly chosen and its value is determined by both pixels in the original image and the elements in key-streams obtained by three one-dimensional chaotic mappings, and the current encrypting pixel’s value is set to be associated with the previous encrypted pixel. Under our framework, the proposed encryption scheme is highly sensitive to minor di?erences in both secret key and plain image, resulting in resisting chosen/known plaintext attacks e?ectively. Simulation results show that the proposed scheme demonstrates excellent security capacity with high e?ciency, comparing with existing approaches in literature.
关键词： Chaotic mapping,Image security,Permutation-di?usion,Chaotic dynamics,Chaotic cryptography
更新于2025-09-09 09:28:46