Imaging for an occluded object is usually a difficult problem, in this letter, we introduce an imaging scheme based on computational ghost imaging, which can obtain the image of a target object behind an obstacle. According to our theoretical analysis, once the distance between the object and the obstacle is far enough, one can obtain the image of the object by using ghost imaging technique. The wavelength of the light source also affects the quality of the reconstructed image. In addition, if the bucket detector is placed far away from the obstacle, a tiny point-like detector without collecting lens can be applied to realize the imaging. These theoretical results above have been verified with our numerical simulations. Furthermore, the robustness of this imaging scheme is also investigated.

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A systematic study of the chaotic synchronization of Bose-Einstein condensed body is performed using linear coupling method based on Lyapunov stability theory, Sylvester's criterion, and Gerschgorin disc theorem. The chaotic synchronization of Bose-Einstein condensed body in moving optical lattices is realized by linear coupling. The relationship between the synchronization time and coupling coefficient is obtained. Both the single-variable coupling and double-variable coupling are effective. The results of numerical calculation prove that the chaotic synchronization of double-variable coupling is faster than that of single-variable coupling and small coupling coefficient can achieve the chaotic synchronization. Weak noise has little influence on synchronization effect, so the linear coupling technology is suitable for the chaotic synchronization of Bose-Einstein condensate.

The conventional photon blockade (CPB) for high-frequency mode is investigated in a second-order nonlinear system with Kerr nonlinearity. By solving the master equation and calculating the zero-delay-time second-order correlation function g(2)(0), we obtain that strong photon antibunching can be achieved in this scheme. The optimal condition for strong antibunching is also calculated analytically and discussed in detail. We find that the Kerr nonlinearity can largely enhance the CPB effect in the high-frequency mode, and this scheme is not sensitive to the reservoir temperature. In addition, when compared with the linear coupled system, the system has obvious advantages in CPB implementation.

In this paper, the unconventional photon blockade is studied in a three-wave-mixing system with a non-degenerate parametric amplification. A method of only retaining the Fock-state basis in the interference path is used to calculate the optimal analytic conditions of unconventional photon blockade. The numerical results agree well with the analytic conditions, which verifies the validity of this method. Our calculations indicate that the strong photon antibunching can be obtained in the high-frequency mode of the three-wave mixing. And the influence of system parameters on photon blockade is also discussed.