共查询到19条相似文献,搜索用时 171 毫秒
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运用全量子理论研究了依赖强度耦合的级联三能级原子系统中双模压缩真空初态场的压缩及量子统计性质,并讨论了初始光场的压缩参量以及原子—光场单光子失谐量对光场非经典性质的影响. 相似文献
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应用Pegg和Barnett提出的相位算符和相位态理论,研究了激发压缩真空态的相位概率分布特性.数值计算结果表明,激发压缩真空态的相位概率分布主要受到相位参量和压缩参量的调节,相位参量使相位概率分布呈峰值结构,压缩参量的变化将影响相位概率分布的峰值强度,此外激发光子数对相位概率分布也有较大的影响. 相似文献
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碱金属原子跃迁线波段压缩态光场是量子信息以及精密测量领域的重要量子资源.碱金属原子跃迁线波长短(760—860 nm),受限于非线性晶体的灰迹效应,光参量放大器制备的此波段压缩态光场的压缩度有限,目前典型值约3—5 dB.本文在光参量放大器的理论模型基础上,结合原子跃迁线波段压缩态光场实验制备面临的问题,研究光参量放大器输出光场量子噪声随其物理参数的变化规律,获得最优的物理参数.构建了级联光参量放大器的理论模型,以此为基础分别在分析频率2 MHz和100 kHz,研究了级联环路光学损耗以及相位噪声对级联系统输出量子噪声特性的影响.研究发现,对于兆赫兹波段的压缩,在低的光路损耗以及位相噪声前提下,级联2—3个光参量放大器可实现压缩的显著提升;对于低频段压缩,级联系统对压缩的增强较小.在目前的实验参数条件下,进一步探究了级联系统输出压缩态光场的量子极限以及频谱特性.本研究可为原子跃迁线波段压缩态光场压缩度的提升提供参考和指导. 相似文献
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频率失谐对相干光脉冲合并和面积演化的影响 总被引:1,自引:1,他引:0
本文首先讨论有频率失谐情况下的光与二能级原子关统相互作用方程,然后在计算机上进行数值模拟,结果表明:如果光场中心频率与原子跃迁频率不一致,光脉冲在吸收介质中没有稳态面积,并且当频率失谐较大(δ≠0)时,脉冲的合并和分裂现象会消失;另外,频率失谐会使单脉冲的压缩和加宽效应增强。 相似文献
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压缩真空中的三能级原子的自发辐射强场高次谐波时间特性的理论分析 总被引:1,自引:0,他引:1
对压缩真空与V型三能级原子的相互作用作了理论分析, 探讨了量子干涉效应对压缩真空中原子自发辐射的影响。当原子的上能级简并时强的量子干涉效应影响原子的定态和定态出射光谱, 使它们对原子的初态敏感。这种情况下, 压缩使谱线趋于关于压缩真空中心频率对称, 量子干涉使谱线趋于不对称。通过用单电子近似求解含时薛定谔方程, 用加窗傅里叶分析的方法, 分析了单原子产生的高次谐波的时间特性。理论分析表明, 基态粒子数消耗对不同级次谐波辐射的影响程度不一样; 谐波辐射随着入射激光场强度的增加会出现饱和; 随着谐波级次的增加, 谐波辐射越来越趋向于集中在更短的时间间隔内, 相应的线宽也随着谐波级次的增加而增加。 相似文献
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压缩相干态光场与Λ型三能级原子相互作用的纠缠特性 总被引:1,自引:1,他引:0
利用量子熵理论,研究了压缩相干态光场与Λ型三能级原子的量子纠缠随时间的演化特性.结果表明:光场与原子纠缠度依赖于初态原子能级叠加系数、光场压缩参量、相干态振幅参量及失谐量与耦合系数之比.当光场压缩参量增大时,光场与原子的最大纠缠度增大;若场失谐量与耦合系数之比增大,光场与原子纠缠则呈现周期性演化,系统呈现接近退纠缠;若场失谐量与耦合系数之比增大,光场与原子纠缠呈现周期性,场失谐量与耦合系数的比值足够大时,在一定时刻系统可处于稳定的最大纠缠态,且系统演化呈现周期性. 相似文献
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利用全量子理论,研究了多光子Jaynes-Cummings模型中与Glauber-Lachs态相互作用的混合态原子的信息熵压缩。讨论了相干平均光子数、热平均光子数、跃迁光子数、原子初态参量对原子信息熵压缩的影响。结果表明原子信息熵 分量没有熵压缩性质;相干平均光子数取值适当时,原子信息熵 分量呈现熵压缩效应;热平均光子数、跃迁光子数会破坏原子信息熵 分量的熵压缩效应;原子初态参量对原子信息熵 分量能否呈现熵压缩效应没有决定性作用;伴随双光子跃迁时,原子的熵压缩因子的时间演化曲线呈现周期性。 相似文献
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Z.-C. Wang Z.-Y. Chen Y. Xu 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,4(2):185-190
A theoretical study is made of the steady-state populations of a three-level atom in a ladder configuration, driven by a superposition
of a monochromatic laser wave with a broad-band squeezed vacuum. The master equation for the system and the atomic Bloch equations
are derived. The steady-state populations are calculated numerically and shown graphically as functions of two-photon detuning
for various cases of the squeezed vacuum. It is shown that, the atomic populations depend strongly on the relative phase of
the driving field and the squeezed vacuum. When the phase matching condition is fulfilled, there will be a strong two-photon
resonant absorption from the squeezed vacuum, a characteristic different from absorption of photons from a classical field.
Received: 28 May 1997 / Revised and Accepted: 10 December 1997 相似文献
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A study is made of the steady-state populations of a three-level ladder atom in a squeezed vacuum, driven by a superposition of a monochromatic laser wave with incoherent population pumping. Using the density matrix equations for the system, the steady-state populations are calculated numerically and shown graphically as functions of two-photon detuning for various cases of the squeezed vacuum and different incoherent pump rates. It is shown that the incoherent population pumping tends to greatly decrease the two-photon absorption from the squeezed vacuum. 相似文献
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Pulse evolutions with SIT-like propagation are shown in spite of including the optical Stark effect and the self-phase modulation by solving numerically the two-photon Bloch equation and the coupled phase and amplitude equations. 相似文献
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Xun-Li Feng Zhao-Yang Chen Zhi-Zhan Xu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(1):117-121
The nondegenerate two-photon interaction of a two-level atom with a broadband multimode squeezed vacuum is investigated. We
find that in the two-photon process the squeezed vacuum has a driving effect on the atom which can lead to an ac Stark effect
when the average photon number of the squeezed vacuum is larger than a critical value.
Received: 2 February 1999 / Received in final form: 20 April 1999 相似文献
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The master equation for a two-level atom driven by a strong classical field and damped into a tailored reservoir with nonflat density of modes is derived under the Born-Markov approximation. To derive the master equation, the dressing transformation on the atomic operators is performed first, and, next, the dressed operators are coupled to the reservoir and the corresponding damping rates are calculated. The effects of a strong field and/or structured reservoir are seen as nonstandard terms in the master equation, some of which are reminiscent of terms known for squeezed vacuum reservoirs. The master equation leads to the generalized optical Bloch equations that can easily be solved for the steady state and, together with the quantum regression theorem, allow for analytical expressions for the fluorescence, as well as absorption spectra. 相似文献
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以一维不对称π共轭分子体系(DBASVP分子)为介质,在双光子共振条件下,从双光子面积定理和严格数值求解Maxwell-Bloch方程两方面出发,分别研究超短脉冲激光在该有机分子介质中的传播过程,从而探讨双光子面积的演化规律,并分析双光子面积定理的适用性.提出了一种数值模拟分子介质光限幅特性的理论方法.分子的电子结构和电偶极矩是基于密度泛函理论利用从头计算方法得到的.研究结果表明,基于慢变幅和慢变相近似以及单模场条件下的双光子面积定理不能很好地描述超短脉冲的双光子面积在该分子介质中的演化规律.基于双光子吸收的分子光限幅特性与分子介质的厚度有关.
关键词:
双光子吸收
光限幅效应
双光子面积定理
超短脉冲激光 相似文献
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We introduce a scheme for creating continuous variable entanglement between an atomic beam and an optical field, by using squeezed light to outcouple atoms from a Bose-Einstein condensate via a Raman transition. We model the full multimode dynamics of the atom laser beam and the squeezed optical field and show that, with appropriate two-photon detuning and two-photon Rabi frequency, the transmitted light is entangled in amplitude and phase with the outcoupled atom laser beam. The degree of entanglement is controllable via changes in the two-photon Rabi frequency of the outcoupling process. 相似文献
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