Case Studies of Atomic Processes in Strong Fields: New Aspects of Multiphoton and Nonlinear Dynamics

Viktor A Kovarskii

Vladimir V. Likhanskii

Jing Qian, Weiping Zhang

We theoretically investigate the effect of dissipation on multiphoton excitation of Rydberg atoms. The steady states and the dynamics are compared via two types of four-level excitation schemes with different dissipative paths of spontaneous emission. We find that in the case of strong Rydberg-Rydberg interaction, the schemes will settle in several different nonequilibrium steady states. The interesting aspect is that there exist the multistable steady states, which reveals the competition between interaction-induced nonlinearity and dissipation caused by spontaneous emission. A numerical simulation on the Rydberg population dynamics in the bistable region exhibits different features existing in the two schemes even with the same initial conditions, which accounts for the influence of the dissipation on the dynamics.

В.В. Лиханский

Zhao-Min Gao, Jiaqi Li, Ying-Huan Wu +2 more

The realization of correlated multiphoton processes usually depends on the interaction between nonlinear media and atoms. However, the nonlinearity of optical materials is generally weak, making it still very challenging to achieve correlated multiphoton dynamics at the few-photon level. Meanwhile, giant atoms, with their capability for multipoint coupling, which is a novel paradigm in quantum optics, mostly focus on the single-photon field. In this work, by using the method described in Phys. Rev. Res. 6, 013279 (2024), we reveal that the ladder-type three-level giant atom spontaneously emits strongly correlated photon pairs with high efficiency by designing and optimizing the target function. In addition, by encoding local phases into the optimal coupling sequence, directional two-photon correlated transfer can be achieved. This method does not require a nonlinear waveguide and can be realized in the conventional environment. We show that the photon pairs emitted in both the bidirectional and the chiral case exhibit strong correlation properties in both time and space. Such correlated photon pairs have great potential applications for quantum information processing. For example, numerical results show that our proposal can realize the two-photon mediated cascaded quantum system.

Alfred M. Levine, W. M. Schreiber, Andrei N. Weiszmann