We model spontaneous parametric down-conversion (SPDC) as classical difference frequency generation (DFG) of the pump field and a hypothetical stochastic ``vacuum'' seed field. analytically show that second-order spatiotemporal correlations generated from DFG process replicate those signal SPDC. Specifically, for low gain, is consistent with quantum calculation photon's reduced density matrix; ...

Arabic learning experiences continuous development along with developments in linguistics, education, and the current of times. that, used to use classical model, is now starting transform into a digital model. The study this article aims describe model Digital This literature study, where data sources are obtained from various relevant such as books, journals scientific articles related theme....

In this paper we extent our previous studies [1] on coupling coefficients for the so-called most degenerate (also named class-one) representations of SO(n). Here we will present new explicit results for the corresponding 6j-symbols. These coupling coefficients are important in many fields of theoretical physics such as atomic and nuclear physics. For example, in connection with the Jahn-Teller ...

In the 2-dimensional anisotropic classical Heisenberg model with XY-symmetry there are nonplanar vortices which exhibit a localized structure of the z-components of the spins around the vortex center. We study how thermal noise induces a transition of this structure from one polarization to the opposite one. We describe the vortex core by a discrete Hamiltonian and consider a stationary solutio...