Nonlinear processes in a system of resonantly interacting atoms

A. M. Bonch-Bruevich, Sergey G. Przhibel'skii, V. V. Khromov

Evgeniy B. Alexandrov, Marcis P. Auzinsh, Dmitry Budker +3 more

A brief review is given of topics relating to dynamical processes arising in nonlinear interactions between light and resonant systems (atoms or molecules) in the presence of a magnetic field.

Guangling Cheng, Aixi Chen, Wenxue Zhong

We present an efficient scheme for generating the tripartite continuous variable entanglement of microwave radiation in a Δ-type three-level artificial atom placed in a transmission line resonator, simultaneously driven resonantly by two strong electromagnetic fields. We show that it is possible to obtain the full tripartite entanglement with the different frequencies in the presence of atom and cavity decays. In our scheme, interestingly, the nonlinear process of simultaneous parametric downconversion and upconversion interactions between microwave modes can be achieved via quantum interference induced by two classical fields and can be greatly enhanced under the condition of resonant driving of the two classical fields. Such a nonlinear interaction is responsible for the generation of the strong tripartite entanglement among three microwave modes. In practice, the system considered here could offer an alternative for implementing the scalable information processing in the solid-state system.

P. K. Shukla, Bengt Eliasson

A. M. Bonch-Bruevich, Sergey G. Przhibel'skii, V. V. Khromov

Ruzan Sokhoyan, H. H. Azizbekyan, Claude Leroy +1 more

We discuss the strong interaction regime of the nonlinear Landau-Zener problem coming up at coherent photo- and magneto-association of ultracold atoms. We apply a variational approach to an exact third-order nonlinear differential equation for the molecular state probability and construct an accurate approximation describing the whole time dynamics of the coupled atom-molecular system. The resultant solution improves the accuracy of the previous approximation by A. Ishkhanyan et al. [J. Phys. A 39, 14887 (2006)]. The obtained results reveal a remarkable observation that in the strong coupling limit the resonance crossing is mostly governed by the nonlinearity while the coherent atom-molecular oscillations coming up soon after the resonance has been crossed are principally of linear nature. This observation is supposed to be general for all the nonlinear quantum systems having the same generic quadratic nonlinearity, due to the basic attributes of the resonance crossing processes in such systems. The constructed approximation turns out to have a larger applicability range (than it was initially expected) covering the whole moderate coupling regime for which the proposed solution accurately describes all the main characteristics of the system's evolution except the amplitude of the coherent atom-molecule oscillation, which is rather overestimated.