Resonantly Enhanced Continuous-Wave Four-Wave Mixing in a Five-Level Cold Atomic Medium

Using Schroedinger-Maxwell formalism, we propose and analyse a cw four-wave mixing (FWM) scheme for the generation of coherent light in a five-level double-∧ atomic system based on electromagnetically induced transparency. We derive the corresponding explicit analytical expressions for the generated FWM field. The influence of hyperfine sublevel on the amplitude of the generated FWM field is predicted in detail. We also give a brief discussion on the experimental realization of the proposed scheme.     

Bistable Behaviour of N Two-Level Atoms Interacting with the Field inside a High-Q Cavity Containing a Nonlinear Kerr-Like Medium

Taking the intensity-dependent coupling between atoms and cavity mode into account, we investigate a system consisting of N homogeneously broadened two-level atoms interacting with the field inside a single-mode Fabry- Perot cavity containing a nonlinear Kerr-like medium. We derive the steady-state bistable behaviour of the system, and further analyse in details the influence of several critical parameters on the bistable behaviour.     

时间延迟对基因调节回路中生物记忆影响研究

生物记忆是广泛存在于各种生物子系统的一种重要的效应. 基于一个双反馈的基因调节回路模型, 采用数值模拟的方法研究了局部反馈中存在的时间延迟对生物记忆时间的影响. 结果发现, 小量的延迟能够很大地提高生物记忆时间. 并且, 生物记忆随延迟时间呈线性增加. 这种增强模式与噪声对生物记忆时间的提高完全不同. 延迟和噪声对生物记忆的提高可以进行相互的控制增强, 但不会影响对方的增强模式.     

Optical bistability of a composite system induced by a broadband squeezed vacuum

A composite system consisting of a degenerate optical parametric oscillator （DOPO） and N two-level atoms interacting with a broadband squeezed vacuum （SV） centred at frequency cas and an input monochromatic pumping field with a frequency ωp is analysed. The corresponding explicit analytical steady-state solutions in the central mode ωp = ωs are derived, and the result displays optical bistability （OB）. In addition, the influence of the broadband SV on the bistable behaviour is analysed in detail.     

Probe Amplification with or without Population Inversion in a Five-Level Atomic System with Double-Dark Resonances

We theoreticMly investigate the response of the probe amplification in a five-level atomlc system m the presence of interacting double-dark resonances disturbed by introducing an additional signal field. It is found that a large enhancement of the probe amplification with or without population inversion can be achieved by properly adjusting the strengths of the microwave driving field and the signal laser field. From viewpoint of physics, we qualitatively explain these results in terms of quantum interference and dressed states.     

Efficient three-wave mixing in a three-level atomic medium with an assisting microwave driven field

The potential for nonlinear conversion between two laser pulses in a three-level V-type medium with assistance of an auxiliary microwave resonant radiation is studied. The results show that microwave driven field can lead to the parametric generation of a new laser pulse with high conversion efficiency when a weak pump laser pulse is applied.     

Scheme for Preparation of the W State via Cavity QED

We put forward a scheme for preparation of an entangled multiparty W state between different modes of radiation field inside high-Q cavity QED. Our scheme is based on the interaction of a two-level atom with the cavity field with the assistance of a strong classical driving field for precalculated interaction time. In principle, the scheme can be extended to prepare an N-party W state. The required experimental techniques are within the scope of what can be obtained in the microwave cavity QED setup.     

Resonantly enhanced continuous-wave four-wave mixing with spontaneously generated coherence in a five-state cold atomic medium

Using Schroedinger-Maxwell formalism, we propose and analyse a continuous-wave four-wave mixing (FWM) scheme for the generation of coherent light in a five-state double-A atomic system with or without spontaneously generated coherence (SGC) based on electromagnetically induced transparency (EIT). We derive the corresponding explicit analytical expressions for the generated FWM field under the steady-state condition. The influence of hyperfine sublevel and SGC effect on the amplitude of the generated FWM field is predicted in detail via the derived analytical expressions. We also give a brief discussion on the experimental realization of the proposed scheme.