【作者】 张治国；

【导师】 梁麦林；

【作者基本信息】 天津大学 ， 理论物理， 2005， 硕士

【摘要】 奇偶相干态是光子消灭算符平方a²的两个正交归一的本征态,其分别具有两种不同的非经典性质:反聚束效应和压缩效应。本文利用一个具有合适速度的叠加态二能级原子,让其先后经过装有相干态光场的腔和Ramsey带,在大失谐近似下再对原子进行选态测量得到的态|Ψ₁ >,|Ψ₂>即为所需的奇偶相干态。当腔场中加入非线性Kerr介质并考虑Stark效应时,在有限失谐近似下,|Ψ₁ >,|Ψ₂>将偏离奇偶相干态。这时,我们再分别研究Kerr介质和Stark效应对|Ψ₁ >,|Ψ₂>二态的非经典性质的作用。此外我们还研究了随时间演化的|Ψ₁ （t ）>,|Ψ₂ （ t ）>受Kerr介质和Stark效应的影响。采用时间演化算符方法,本征值、本征函数法（将哈密顿量对角化）和数值计算后,我们发现,在随平均光子数n变化的|Ψ₁ >,|Ψ₂>的图中,随着Kerr介质参量χ/λ增强或Stark参量β₂/β₁比值的减小, |Ψ₂>反聚束效应减弱, |Ψ₁ >则增强,而压缩效应则会随着χ/λ或β₂ /β₁比值的增大而减弱。在随时间演化的|Ψ₁ （t ）>,|Ψ₂ （ t ）>的图中,光场的二阶相干度和压缩效应,在共振情况下,随着平均光子数n的增大,均出现了明显的周期性崩塌和回复现象。随着失谐量△/λ的增大,回复时间也加大了。随着χ/λ和β₁;β₂的增大,减小了回复时间,直到最后现象消失了,只剩下震荡图像。更多还原

【Abstract】 Odd and even coherent states are two vertical normalizing eigenstates of thesquare of annihilation operators in the optical field,which have two differentnon-classical properties respectively, anti-bunching and squeezing effect. In this paper,let a superposed two-level atom with appropriate velocity pass successively through acavity with coherent optical field and a Ramsey strap. Then the coherent state that weneed is got by selective measure in a large detuning limit. The states|Ψ₁ >&| Ψ₂>will deviate from odd-even coherent state when the cavity is filled with nonlinear Kerrmedium and the Stark effect is considered. Thus, we study the effect of Kerr mediumand the Stark effect respectively by acting on non-classical properties ofstate|Ψ₁ >&| Ψ₂>. Furthermore, the properties of time-evolution of states|Ψ₁ （t ）>&| Ψ₂ （ t ）> affected by Kerr medium and the Stark effect are also discussed.By means of the method of time-evolution operator 、 eigenvalues andeigenfunction and numerical calculation, we can find that in the chart of|Ψ₁ >,| Ψ₂>,altering with average of phonon-number, anti-bunching effect of state | Ψ₂> isweaken but that of the state |Ψ₁ > is strengthened with parameter χ/λ enhancing orthe ratio of β₂/β₁ weakening and in the meantime squeezing effect is weaken.In the chart of state |Ψ₁ （t ）>,| Ψ₂ （ t ）> evolving with time, the phenomenon ofperiodical collapse-revival of the 2nd-order coherent degree and squeezing effects ofoptical field appears clearly with the increase of average photon numbers under thecondition of resonance. The revival time is lengthened with the detuningparameter △/λ, and that is shortened under the conditions of parameter χ/λ orβ₁ &β₂ increasing till the phenomenon of periodical collapse-revival disappears andremains the common oscillation chart.更多还原