共查询到18条相似文献,搜索用时 203 毫秒
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运用密度矩阵理论,研究了在外加相干耦合场作用下∧型四能级系统的吸收和色散特性。数值模拟表明:通过调节外加相干场的拉比频率强度,该系统可以单重、双重电磁诱导光透明现象,并在缀饰态表象中给出了定性解释。在双重电磁诱导透明现象中,透明窗的位置和吸收峰值可以通过调节外加相干场的失谐量来进行控制,而且透明点的位置可以连续变化。每个透明窗口在吸收最低时都伴随着高折射率,因此可以在此介质中实现超光速传播。 相似文献
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准Λ型4能级系统具有电磁诱导吸收(EIA)和电磁诱导透明(EIT)两种特性.准Λ型4能级系统包括两个基态精细结构能级和两个激发态精细结构能级,除光学耦合场和探测场外,附加了一个射频场作用于两个激发态精细结构能级之间.若对此系统进行拓展,在两个基态精细结构能级之间引入一个驱动场,则构成4场作用下的闭合Λ型4能级系统.本文对新引进的驱动场的作用规律进行了重点研究.研究结果表明,当驱动场和射频场的Rabi频率满足不同关系时,系统呈现EIA或EIT两种不同特性,探测吸收曲线的整体轮廓也随之改变. 相似文献
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当用两个微波场作用到Λ型三能级原子的耦合跃迁的基态与另两个超精细能态构成的跃迁时,由微波场诱导产生的两个高对比度共振吸收线将单重电磁诱导透明谱分裂成三个透明窗口。通过调节微波场的强度或失谐量,可实现对原子透明谱进行局域调制。采用缀饰态理论对展示的物理现象进行了解释。这些研究对多通道光通信和原子的可控调制等方面有一定的作用。 相似文献
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本文运用Dressed原子态方法;把四能级原子与两个激光场和一个探测场的相互作用转化为四能级原子与一个弱探测吸收场的相互作用,然后采用微扰理论求解Dressed原子表象中的密度矩阵方程,得出吸收谱的解析表达式,并详细讨论了吸收谱的各种持性.最后,导出了由外场感应的能级间的电偶极矩表达式,并找出了吸收谱与它的关系. 相似文献
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构建双耦合场作用下的N-型四能级系统,详细讨论系统的探测吸收特性随两个耦合场Rabi频率取不同值时的变化规律,得到EIT、Mollow和Autler-Townes双峰效应及其它们之间的相互转化规律。通过找出N-型四能级系统中的多个跃迁通道,将系统按跃迁通道拆分成多个子系统,不同的拆分方法实现了不同跃迁通道之间的量子干涉,从而使系统呈现出三种产生条件和物理本质不同的非线性效应。 相似文献
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当两束激光以Λ-构型作用于三能级原子系统并满足双光子共振条件时,探测激光场吸收谱呈现电磁诱导透明(EIT)特征.若再加一个微波控制场作用于该三能级系统的两个低能级跃迁之间,会导致探测吸收特性明显变化,EIT窗口将发生劈裂.通过求解相应的密度矩阵方程,揭示了外加微波场作用下EIT窗口的变化规律,并给出了相应的缀饰态解释.研究结果表明,在适当的条件下, 电磁诱导透明呈现三重结构,而EIT窗口的频率位置取决于微波控制场的拉比频率及频率失谐量.因此通过改变微波控制场的参数可以实现多EIT窗口的频率调谐.
关键词:
电磁诱导透明
量子相干
频率调谐
多窗口EIT 相似文献
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在通常的Λ型三能级系统中,光学耦合场和探测场分别激发两个不同的光学跃迁,探测吸收谱呈现电磁诱导透明(EIT)特性.若将此系统拓展为光学-射频双光子耦合场和探测场共同作用下的准Λ型四能级系统,探测吸收谱呈现电磁诱导吸收(EIA)和EIT两种特性.通过求解系统的密度矩阵方程,分析了EIA和EIT的产生条件,并给出了相应的缀饰态解释.研究结果表明,在准Λ型四能级系统中,光学耦合场对EIA和EIT的形成起决定作用,共振时出现EIA,非共振时出现EIT,而且EIA和EIT的线宽随着光学耦合场拉比频率的增大而增加.
关键词:
电磁诱导透明
电磁诱导吸收
射频场
光学耦合场 相似文献
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ZHANG Liying LIU Zhengdong & CHEN Jun Institute of Modern Physics Nanchang University Nanchang China 《中国科学G辑(英文版)》2005,48(5):593-599
Quantum interference and atomic coherence have led to the observation of many striking phenomena in the multilevel atoms. The notable examples include electromag-netically induced transparency (EIT)[1], coherent population trapping (CPT)[2], lasing without inversion[3], spontaneous emission spectrum[4], etc. Recently, it was found that one could obtain the enhancement of Kerr nonlinearities by electromagnetically induced transparency and cold atom technology, such as the scheme of a giant K… 相似文献
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Phase-dependent inversionless gain in a four-level atomic system with a closed interaction loop 下载免费PDF全文
A four-level atomic system with a closed interaction loop connected
by two coherent driving fields and a microwave field is
investigated. The results show that inversionless gain can be
achieved on a higher frequency transition outside the closed
interaction loop, and the gain behaviour can be modulated by the
phase of the closed loop as well as the amplitude of the microwave
field. The phase sensitivity property in such a scheme is similar to
that in an analogous configuration with spontaneously generated
coherence, but it is beyond the rigorous condition of
near-degenerate levels with non-orthogonal dipole moments.
Therefore this scheme is much more convenient in experimental
realization. 相似文献
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在n型四能级原子系统中,研究了电磁感应吸收的非线性理论.结果表明:探测光的拉比频率和衰减分配系数A影响非线性吸收,进而影响介质吸收.当探测光光强较弱时,介质吸收和线性吸收一致,均表现为电磁感应吸收特征;当探测光光强增大时,介质吸收和线性吸收不再一致,介质吸收曲线将会呈现出烧孔现象;当探测光光强增大到控制光(或信号光)光强时,介质吸收表现出很大的增益现象.同时,非线性吸收受到衰减分配系数A的影响,即使在探测场很弱的条件下,随着A值的减小,介质吸收由电磁感应吸收现象表
关键词:
电磁感应吸收
非线性吸收
增益现象
n型四能级原子系统 相似文献
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主要研究了室温下微波场缀饰的铯Rydberg原子的电磁感应透明-Autler-Townes(EIT-AT)光谱.首先,以铯原子6S_(1/2)→6P_(3/2)→50S_(1/2)形成阶梯型三能级系统,利用强耦合光作用于6P_(3/2)→50S_(1/2)的Rydberg跃迁,弱探测光耦合基态跃迁6S_(1/2)→6P_(3/2)并探测由耦合光形成的电磁感应透明(EIT)效应.然后,以频率为30.582 GHz的微波电场耦合相邻的Rydberg能级50S_(1/2)→50P_(1/2)产生微波AT分裂.利用Rydberg EIT探测微波耦合相邻Rydberg能级产生的AT分裂,形成EIT-AT光谱,进而实现微波电场的测量.当微波场的强度增加到一定值时,EIT-AT光谱表现为多峰光谱结构.分析EIT-AT多峰光谱的成因,发现这主要是由场的不均匀性导致的,一定的EIT-AT光谱特征对应于特定的非均匀场分布.研究表明,利用Rydberg EIT-AT光谱可以实现微波电场的测量,利用其光谱特征可实现微波场的实时监测,进而提出了一种提高微波场空间分辨率的测量方法. 相似文献
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We present a detail analysis of the line shape of electromagnetically induced transparency (EIT) in a Doppler broadened five level atomic system based on density matrix formalism. It has been shown that the velocity averaged EIT line shape in a multilevel system is very sharp. The effect of the ground state decay rates on the EIT peak has also been investigated. The linear and non-linear variations of the EIT line width (FWHM) for different pump and probe power ratios are shown. Considering the D2 transition of 85Rb atom the dependence of EIT width and height on pump power has been experimentally measured. Simulated spectra are compared with the experimentally obtained one. The effect of buffer gas on the EIT peak has also been observed experimentally as well as theoretically. 相似文献
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Effect of four-wave mixing on electromagnetically induced transparency in Λ-type system with a two-photon probe field 下载免费PDF全文
Using density matrix equation, we calculate analytically as well as numerically the effect of the four-wave mixing (FWM) field on electromagnetically induced transparency (EIT) in the rubidium 5S_{1/2}-5P_{3/2}-5D_{5/2} Λ-type system with a two-photon probe field. The calculated results are in good agreement with Fulton's experimental results in 1995 Phys. Rev. A 52 2302. 相似文献
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In this paper, we suggest a doubly degenerate four-level system, in which the transition takes place between the hyperfine energy 52S1/2 F = 1 and 52P3/2 F = 2 in rubidium 87 D2 line, for studying atomic phase grating based on the cross-Kerr and phase conjugation effects. The phase grating with high efficiency can be obtained by tuning phase shift Ф between the coupling and probe field, when the coupling intensity is much stronger than the strength of probe field. Under different coupling intensities, a high diffraction efficiency can be maintained. A new and simple way of implementing phase grating is presented. However, in such an atomic system, two main limitations must be taken into account. First, the independence between steady state probe susceptibility and the coupling intensity, when the population decay rate is larger than the Rabi frequency of the coupling field, cannot result in diffraction grating; second, the sample to be prepared should not be too long. 相似文献