光学-射频双光子耦合作用下的电磁诱导透明和电磁诱导吸收

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     

闭合Λ型4能级系统中的电磁诱导透明和电磁诱导吸收

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.     

耦合场失谐对闭合Λ型四能级系统中电磁诱导透明和电磁诱导吸收的影响

电磁诱导透明(EIT)和电磁诱导吸收(EIA)是光与物质相互作用中表现出来的奇特的非线性效应,对其形成机理及非线性特性的研究具有重要的理论意义和巨大的潜在应用价值.构建一个闭合Λ型四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,除耦合场和探测场外,还附加了两个射频场分别作用于激发态精细结构能级和基态精细结构...     

探测功率展宽效应引起的电磁诱导透明向电磁诱导吸收的转化

本文对准L型四能级系统中探测功率展宽效应引起的非线性效应进行了理论研究.准L型四能级系统包括三个基态精细结构能级和一个激发态能级,除光学耦合场和探测场分别激励一个基态精细结构能级和激发态能级之间的跃迁外,附加了一个射频驱动场作用于其中一个基态精细结构能级和另一个新的基态精细结构能级之间,并通过与耦合场驱动共同能级建立量子相关性.研究结果表明,在射频驱动场的辅助激励下,探测功率展宽效应不仅可以使EIT的线宽增宽,还能引起吸收曲线中的类色散特性,使EIT最终变化为EIA.     

探测功率展宽效应引起的电磁诱导透明向电磁诱导吸收的转化

本文对准型四能级系统中探测功率展宽效应引起的非线性效应进行了理论研究。准型四能级系统包括三个基态精细结构能级和一个激发态能级,除光学耦合场和探测场分别激励一个基态精细结构能级和激发态能级之间的跃迁外,附加了一个射频驱动场作用于其中一个基态精细结构能级和另一个新的基态精细结构能级之间,并通过与耦合场驱动共同能级建立量子相关性。研究结果表明,在射频驱动场的辅助激励下,探测功率展宽效应不仅可以使EIT的线宽增宽,还能引起吸收曲线中的类色散特性,使EIT最终变化为EIA。     

四能级原子系统中的电磁诱导吸收

以三个电偶极跃迁(中间跃迁作为探测跃迁、两边分别是耦合跃迁和控制跃迁)构成N型四能级系统为例，研究介质对探测光的吸收.揭示了在N型四能级系统中，既可产生电磁诱导吸收又可产生电磁诱导透明.这不仅取决于非相干转移率的大小，而且还取决于耦合场、控制场的强度和第四个简并能级的衰减速率大小. 关键词： 电磁诱导吸收 电磁诱导透明 原子相干的自发转移 能级的衰减速率     

射频驱动精细结构能级跃迁引起的非线性效应

研究了射频驱动精细结构能级跃迁引起的电磁诱导透明(EIT)和电磁诱导吸收(EIA)的转化.通过采用射频场同时驱动激发态和基态精细结构能级跃迁,使系统中出现EIT和EIA.研究结果表明,调谐射频场频率从与基态精细结构能级共振到与激发态精细结构能级共振的过程中,EIT和EIA相互转化,而且射频场的拉比频率取值不同,EIT和EIA的变化规律也不同.     

射频驱动精细结构能级跃迁引起的非线性效应

研究了射频驱动精细结构能级跃迁引起的电磁诱导透明（EIT）和电磁诱导吸收（EIA）的转化。通过采用射频场同时驱动激发态和基态精细结构能级跃迁,使系统中出现EIT和EIA。研究结果表明,调谐射频场频率从与基态精细结构能级共振到与激发态精细结构能级共振的过程中,EIT和EIA相互转化,而且射频场的拉比频率取值不同,EIT和EIA的变化规律也不同。     

电磁诱导吸收介质中探针场的量子噪声特性

在N型原子系统中,在二束强的耦合场作用于介质对探针场体现出很强的诱导吸收作用,与此同时,强吸收引起的自发辐射噪声会影响探针场的量子噪声特性.该文章研究了输入的量子化探测场在经过电磁诱导吸收介质后的噪声特性变化,数值模拟得出,通过调节控制场的强度可以使得探测场的噪声谱图形在吸收窗口范围内产生震荡分裂,噪声最小值处于一定的探针场失谐处.     

耦合场线宽：抑制电磁诱导吸收

原子相干对吸收的相长干涉导致电磁诱导吸收，这是一类新的相干效应. 以三个电偶极跃迁构成N型链，中间跃迁作为探测跃迁的四能级系统为例，揭示耦合场线宽抑制电磁诱导吸收的强度. 这并非与电磁诱导透明系统中耦合场线宽产生或者增强吸收的情形相矛盾，线宽仍然是抑制系统的相干性. 关键词： 电磁诱导吸收 耦合场线宽 原子相干 退相干     

调谐耦合场作用下的电磁诱导透明和增益

在通常的A型三能级系统中,耦合场和探测场分别与一对光学跃迁能级发生相互作用,使探测吸收曲线上出现线宽极窄的电磁诱导透明(Electromagnetically Induced Transparency,EIT)特性.本文采用调谐耦合场同时激励两个基态精细结构能级与激发态能级之间的跃迁,使系统同时呈现EIT和自发诱导相干...     

Electromagnetically Induced Transparency and Absorption of A Monochromatic Light Controlled by a Radio Frequency Field

Electromagnetically induced transparency and absorption of a monochromatic light controlled by a radio frequency field in the cold multi-Zeeman-sublevel atoms are theoretically investigated. These Zeeman sublevels are coupled by a radio frequency(RF) field. Both electromagnetically induced transparency and electromagnetically induced absorption can be obtained by tuning the frequency of RF field for both the linear polarization and elliptical polarization monochromatic lights. When the transfer of coherence via spontaneous emission from the excited state to the ground state is considered, electromagnetically induced absorption can be changed into electromagnetically induced transparency with the change of intensity of radio field. The transparency windows controlled by the RF field can have potential applications in the magnetic-field measurement and quantum information processing.     

电磁感应双光子光透明及共振吸收增强

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级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。     

Broadband Plasmon-Induced Transparency to a Electromagnetically Induced Absorption Conversion Metastructure Based on Germanium

A Germanium (Ge) metastructure with switching features from broadband plasmon-induced transparency (PIT) and electromagnetically induced absorption (EIA) is presented, which forms a broadband PIT through the near-field coupling between the localized plasmon resonance and the Mie resonance employing four gold cut wires as bright plasmon resonators and four C-shaped dielectric rings as dark plasmon resonators. A wide transparent window above 0.9 is achieved covering from 0.622 to 0.823 THz with a relative bandwidth of 27.8%. In addition, through phase modulation, a magnetic dipole is generated by the constructive interference of the near-field coupling of the three resonators to realize the PIT to EIA conversion. In addition, a grid-like metastructure is introduced to realize the PIT to EIA conversion by phase modulation. To enhance the EIA bandwidth, another layer of C-shaped reflection plate resonator is introduced to increase the dark mode loss, and a layer of frequency selective surface composed of cross-shaped resonators is also used. Thus under the dual effect, a wide absorption window above 0.75 is achieved covering from 0.647 to 0.756 THz with a relative bandwidth of 15.5%.     

Electromagnetically Induced Transparency in a Four-Level Atomic System

In this paper, we analyze and discuss the absorption properties of the probe beam in a four-level atomic system with a nearly hyper-fine doublet structure of two higher-lying excited levels based on electromagnetically induced transparency (EIT) for the two cases of transient process and steady-state process. The main gain of this work is to investigate theoretically the influence of the nearly hyper-fine levels on the probe absorption. For the transient process,using the numerical calculations by a simple Mathematica code we find that the magnitude of the probe absorption at the line center is small compared to the typical three-level atomic system in the context of electromagnetically induced transparency. For the case of the steady state, our results show that the probe absorption can be completely eliminated at the line center of the probe transition just as the usual three-level EIT scheme.     

Full Quantum Theory of Transient-State Electromagnetically Induced Transparency

We develop a full quantum theory of transient-state electromagnetically induced transparency (EIT) in thevapor of three-level A-type atoms interacting with probe and coupling lasers. As applications of the full quantum theory,we show that transient-state EIT medium exhibits normal dispersion and find that group velocities of both coupling andprobe lasers are greatly reduced. It is shown that the group velocity of the probe laser in the transient-state EIT case isequal to that in the adiabatic EIT case and that the coupling laser group velocity in the transient-state EIT is generallyless than that in the adiabatic EIT.     

Electromagnetically Induced Transparency in a Four-Level Atomic System

In this paper, we analyze and discuss the absorption properties of the probe beam in a four-level atomic system with a nearly hyper-fine doublet structure of two higher-lying excited levels based on electromagnetieally induced transparency (EIT) for the two cases of transient process and steady-state process. The main gain of this work is to investigate theoretically the influence of the nearly hyper-fine levels on the probe absorption. For the transient process, using the numerical calculations by a simple Mathematica code we find that the magnitude of the probe absorption at the line center is small compared to the typical three-level atomic system in the context of electromagnetieally induced transparency. For the case of the steady state, our results show that the probe absorption can be completely eliminated at the line center of the probe transition just as the usual three-level EIT scheme.     

Full Quantum Theory of Transient-State Electromagnetically Induced Transparency

We develop a full quantum theory of transient-state electromagnetically induced transparency (EIT) in the vapor of three-level A-type atoms interacting with probe and coupling lasers. As applications of the full quantum theory, we show that transient-state EIT medium exhibits normal dispersion and find that group velocities of both coupling and probe lasers are greatly reduced. It is shown that the group velocity of the probe laser in the transient-state EIT case is equal to that in the adiabatic EIT case and that the coupling laser group velocity in the transient-state EIT is generally less than that in the adiabatic EIT.     

Electromagnetically Induced Transparency in an Atom-Molecule Bose-Einstein Condensate

We propose a new measurement scheme for the atom-molecule dark state by using electromagnetically induced transparency （FIT） technique. Based on a density-matrix formalism, we calculate the absorption coefficient numerically. The appearance of the EIT dip in the spectra profile gives clear evidence for the creation of the dark state in the atom-molecule Bose--Einstein condensate.     

Electromagnetically Induced Transparency in an Atom-Molecule Bose-Einstein Condensate

We propose a new measurement scheme for the atom-molecule dark state by using electromagnetically induced transparency (EIT) technique. Based on a density-matrix formalism, we calculate the absorption coefficient numerically. The appearance of the EIT dip in the spectra profile gives clear evidence for the creation of the dark state in the atom-molecule Bose-Einstein condensate.