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1.
研究了相干场控制下的电磁感应双光子光透明。讨论了外加相干场对双光子吸收特性的影响,分析了电磁感应双光子光透明及共振吸收增强的物理机制。应用密度矩阵方法推导出相干场作用下双光子吸收上能粒子数的二阶近似表达式,同时利用微扰法在原子缀饰态表象中推导出双光子跃迁速率的解析表达式。并讨论了系统中多普勒效应的影响。 相似文献
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本文研究了倒Y型四能级系统中自发辐射诱导相干对探测场的色散和吸收特性的影响。在稳态条件下利用密度矩阵微扰理论推导出了密度矩阵的迭代解。数值分析了自发辐射诱导相干对线性和非线性折射率和吸收系数的影响,分析了泵浦场和耦合场偏离双光子共振对弱探测场色散和吸收特性的影响。研究发现自发辐射诱导相干使弱探测光的线性和非线性折射率增强,同时形成一个较宽的透明窗。在没有自发辐射诱导相干的情况下,泵浦场和耦合场偏离双光子共振对探测场的线性和非线性折射率影响明显,在有自发辐射诱导相干的情况下,泵浦场和耦合场偏离双光子共振使得探测场的线性透明窗变窄,非线性吸收增加。 相似文献
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研究驻波场相干驱动下四能级双Lamder模型的电磁感应光子带隙。当耦合场是远共振或共振时,来自于两邻近能级间的自发辐射相干效应(SGC)有助于实现一个或两个光子带隙。当自发辐射相干效应不存在时,探测场被原子系统强烈吸收,因此导致光子带隙严重形变甚至无法形成。数值结果表明,光子带隙结构是由SGC效应导致探测场和耦合场之间的相干增强Kerr非线性调制而产生,并改变驻波场的耦合方式,使系统实现单光子带隙转变为双光子带隙的动态调控。 相似文献
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研究驻波场相干驱动下四能级双Lamder模型的电磁感应光子带隙.当耦合场是远共振或共振时,来自于两邻近能级间的自发辐射相干效应(SGC)有助于实现一个或两个光子带隙.当自发辐射相干效应不存在时,探测场被原子系统强烈吸收,因此导致光子带隙严重形变甚至无法形成.数值结果表明,光子带隙结构是由SGC效应导致探测场和耦合场之间的相干增强Kerr非线性调制而产生,并改变驻波场的耦合方式,使系统实现单光子带隙转变为双光子带隙的动态调控. 相似文献
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利用电磁感应透明技术,在一维光晶格中相干驱动四能级Lambda模型冷原子系统,从而实现动力学可调谐电磁感应光子带隙结构。基于两邻近能级间的自发辐射相干(SGC)效应,通过控制耦合场从远共振到共振,使该原子系统实现从两个光子带隙转变为三个光子带隙的动态过程。当自发辐射相干效应不存在时,在探测场共振区域处探测光子被原子系统强烈吸收,因此感应光子带隙严重形变甚至无法形成。通过数值计算证明光子带隙结构的形成源自于自发辐射相干效应下探测场和耦合场之间的三阶交叉克尔(Kerr)非线性调制,并且通过控制耦合场的耦合方式,可以实现系统从两个光子带隙到三个光子带隙的动力学调控。 相似文献
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相干驱动场的线宽对电磁感应透明的影响 总被引:4,自引:3,他引:1
考虑相干驱动场的线宽,探讨了其对双激发态原子三能级系统中的电磁感应透明现象的影响,得到结论:相干驱动场的线宽抑制了介质对弱探测光的透明。 相似文献
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Nonlinear cascade-configuration multi-wave mixing scheme based on electromagnetically induced transparency 下载免费PDF全文
A nonlinear optical cascade-configuration multi-wave mixing (CCMWM) scheme is presented and analysed for the generation of coherent light in a six-level atomic system in the context of electromagnetically induced transparency (EIT). A detailed semi-classical study of the propagation of the generated mixing and probe fields is demonstrated. We show by numerical simulations that EIT is capable of suppressing linear and nonlinear photon absorption. The analytical dependence of the generated mixing field on the probe field and the respective detuning is also predicted. Such a nonlinear optical process can be used for generating coherent short-wavelength radiation. 相似文献
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Electromagnetically induced transparency and electromagnetically induced absorption in Y-type system 下载免费PDF全文
《中国物理 B》2020,(5)
The propagation of a probe field through a four-level Y-type atomic system is described in the presence of two additional coherent radiation fields, namely, the control field and the coupling field. An expression for the probe response is derived analytically from the optical Bloch equations under steady state condition to study the absorptive properties of the system under probe field propagation through an ensemble of stationary atoms as well as in a Doppler broadened atomic vapor medium. The most striking result is the conversion of electromagnetically induced transparency(EIT) into electromagnetically induced absorption(EIA) as we start switching from weak probe regime to strong probe regime. The dependence of this conversion on residual Doppler averaging due to wavelength mismatch is also shown by choosing the coupling transition as a Rydberg transition. 相似文献
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提出了一种基于量子相干控制吸收的对准Λ型四能级原子进行二维局域化方案. 利用密度矩阵微扰理论, 得到了确定原子空间位置信息的筛选函数解析表达式. 在缀饰态表象中, 分析了在相干控制场作用下原子初始状态对原子局域的影响. 数值模拟了控制场参量对原子局域化结果的影响. 研究发现原子局域化结果与初始时刻在控制场作用下原子在下能态的布局、下能级间产生的极化密切相关; 不管探测场与耦合场是否满足电磁感应透明配置条件, 通过改变控制场中的行波场的振幅和探测场的失谐量, 均可实现高精度原子局域化, 在亚波长范围内测量到原子的概率达到100%. 相似文献
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A new approach to observing the effect of electromagnetically induced transparency in gamma optics is proposed. The propagation of a resonant photon in a 57Fe magnetic medium in an applied rf field is considered for this purpose. It is shown that, under crossing-anticrossing conditions, a resonant rf field substantially changes the gamma-optical properties of the medium, which become dependent on the parameters of the field. This opens the possibility for exercising a coherent control of the photon group velocity and a controllable filtration of unpolarized gamma radiation in a sample. 相似文献
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Resonantly enhanced continuous-wave four-wave mixing with spontaneously generated coherence in a five-state cold atomic medium 下载免费PDF全文
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. 相似文献
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采用一束相干外场作用在倒Y模型原子的基态与另外状态构成的跃迁上,实现对单光子和双光子电磁诱导透明谱的调制。经研究发现相干外场对单光子和双光子的吸收性质有类似的影响效果。由于相干外场的作用,吸收谱的共振点附近出现吸收峰将原单重透明谱分裂为双重透明谱。诱导的吸收峰的高度和透明谱的频谱宽度与相干外场的强度有密切关系。并用缀饰态理论解释了这些物理现象。这些研究对多通道光通信以及对原子光学性质的调控方面有积极意义。 相似文献
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In this study, the probe response of a cavity optomechanical system with periodic modulation of the optomechanical coupling is investigated. The modulation arises from the beat effect between two external coherent driving lights, with the beat frequency matching the modulation frequency. The transmission coefficient is derived for the probe field and significant amplification, rather than absorption in the conventional optomechanically induced transparency schemes, is observed near the transparent point when the modulation is introduced. In addition, the coupling modulation can also enhance the slow light effect. 相似文献
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双模纠缠相干光与Bell态原子系统的光子统计 总被引:2,自引:2,他引:0
运用全量子理论并结合数值计算方法,研究了处于Bell态的两个全同二能级纠缠原子与双模纠缠相干光场相互作用系统的光子统计性质.分析了双原子体系的初态、光场的平均光子数、双模纠缠相干光场的纠缠程度以及双原子体系的原子间耦合强度对双模光场的光子统计性质的影响.结果表明:双原子体系的初态为|β00〉、|β10〉时,光场在其演化过程中不出现光子的反聚束效应;而当原子初态为|β01〉或|β11〉时,在一定的条件下可出现光子的反聚束效应.并且在光场的演化过程中,光子的反聚束效应出现的次数、时间和深度极其敏感地依赖于初始光场的平均光子数,而受到双模纠缠光场的纠缠程度以及双原子间偶极作用强度的影响很微弱. 相似文献
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H. J. Li L. Deng G. Huang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(1):99-109
We present a systematical investigation, both analytical and numerical, on the dynamics of two nearly lossless and distortion-free weak nonlinear optical pulses in a cold, lifetime-broadened four-state double-Λ system via electromagnetically induced transparency. Starting from theequations of motion of atomic response and probe fields, we give a detail derivation of two coupled nonlinear Schrödinger equations that control the nonlinear evolution of two probe field envelopes by means of a standard method of multiple-scales. We show that stable optical solitons with very slow propagating velocity can be generated under very low input light intensity when working in the transparency window of probe absorption spectrum induced by two continuous-wave control fields. We demonstrate that coupled optical soliton pairs are possible in the system through cross-phase modulational instability and mutual trapping effect of solitons. We provide various coupled optical soliton pair solutions explicitly and analyze their stability numerically. 相似文献
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Siplified description of unsaturated two-photon absorption. 1. Summation of the short-time expansion
A. Bandilla 《Optics Communications》1985,56(2):122-126
For degenerate unsaturated two-photon absorption the short-time expansion for initially coherent light derived from the exact solution or by iteration is summed. By this approach we derive simple analytical expressions, still decribing photon antibunching and squeezing correctly. In this paper we concentrate on the main diagonal of the field density matrix and show for examples of expectation values how this procedure works. 相似文献