共查询到20条相似文献,搜索用时 15 毫秒
1.
Kanhaiya Pandey 《Optics Communications》2011,284(1):252-255
We analyze theoretically the phenomenon of electromagnetically induced transparency (EIT) under conditions where the probe laser is not in the usual weak limit. We consider the effects in both three-level and four-level systems, which are either closed or open (due to losses to an external metastable level). We find that the EIT dip almost disappears in a closed three-level system but survives in an open system. In four-level systems, there is a narrow enhanced-absorption peak (EITA) at line center, which has applications as an optical clock. The peak converts to an EIT dip in a closed system, but again survives in an open system. 相似文献
2.
High-speed properties of a phase-modulation scheme based on electromagnetically induced transparency
Recently a cross-phase modulation scheme that yields giant Kerr nonlinearities by use of an electromagnetically induced transparency (EIT) was proposed [Schmidt and Imamoglu, Opt. Lett. 21, 1936 (1996)]. We analyze the high-speed properties of this scheme for short-pulse propagation. We discuss the relevant losses in this system and show that for short pulses one-photon losses are dominant. We demonstrate that over the entire bandwidth the attainable phase shift in an EIT scheme with a quasi-cw coupling field is orders of magnitude higher than in a conventional three-level scheme or in EIT schemes, in which matched pulses are used to create the transparency. 相似文献
3.
A. Yu. Kryachko A. G. Litvak M. D. Tokman 《Journal of Experimental and Theoretical Physics》2002,95(4):697-704
We investigate a classical analog of electromagnetically induced transparency (EIT) currently popular in quantum electronics. We consider EIT for electron cyclotron waves in finite-temperature plasma. We derive an expression for the effective refractive index of an electromagnetic wave and study the dispersion and absorption of this wave under EIT conditions. Allowance for thermal motion is shown to radically change the behavior of the dispersion curves for the signal wave in the EIT region compared to the case of cold plasma. 相似文献
4.
Electromagnetically induced transparency in a Zeeman-sublevels Λ-system of cold ~(87)Rb atoms in free space
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We report the experimental investigation of electromagnetically induced transparency(EIT) in a Zeeman-sublevelsΛ-type system of cold ~(87)Rb atoms in free space. We use the Zeeman substates of the hyperfine energy states 5~2S_(1/2), F = 2 and 5~2P_(3/2), F = 2 of ~(87)Rb D_2 line to form a Λ-type EIT scheme. The EIT signal is obtained by scanning the probe light over 1 MHz in 4 ms with an 80 MHz arbitrary waveform generator. More than 97% transparency and 100 k Hz EIT window are observed. This EIT scheme is suited for an application of pulsed coherent storage atom clock(Yan B, et al. 2009 Phys.Rev. A 79 063820). 相似文献
5.
Guangsheng Fu Zhonghong Zhuang Lijun Yang Li Han Changjiang Wei 《Physics letters. A》2008,372(2):176-180
We study electromagnetically induced absorption (EIA) and transparency (EIT) in an optical-rf two-photon coupling configuration. It is shown that the interference effect due to interacting dark resonances results in an EIA for a resonant two-photon coupling and this EIA is observed to evolve into an EIT when there is a detuning in the two-photon coupling. 相似文献
6.
A scheme to observe Electromagnetically induced transparency (EIT) in an optomechanical system is proposed in the current paper. We treat a narrowband squeezed field as the weak probe field. We find that EIT dips exist in the output field. Moreover, the dependence of the EIT dips on the effective cavity detuning Δ and the input power ζ are explored. We show that the width of the EIT dips can be controlled by the parameters ξ and the detuning Δ. 相似文献
7.
研究了Λ型能级系统中, 85Rb原子在耦合光频率失谐较小时的电磁感应透明(EIT)现象. 实验中, 随着耦合光频率失谐量的增加, 电磁感应透明窗口的绝对强度有所减弱, 但是其相对深度却有所增加, 透明窗口相对深度最大的位置不在耦合光频率共振处, 而是在耦合光频率失谐约180 MHz的位置. 用三能级和四能级系统的理论分别对实验结果进行对比分析, 发现用四能级系统的理论进行拟合的结果与实验符合得比较好. 对此, 我们提出当耦合光频率失谐较小时, EIT信号是两个激发态共同作用的结果, 并用四能级系统的理论分析了两个激发态之间的能级间隔对透明窗口相对深度最大值位置的影响. 相似文献
8.
9.
A. L. Gogyan N. V. Sahakyan Yu. P. Malakyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2012,47(4):161-167
We propose a method of all-optical investigation of radiofrequency (RF) radiation based on the coherent effect of electromagnetically induced transparency (EIT). It is shown that if the atomic coherence is perturbed by an RF field, the shape of probe pulse propagating in a three-level ??-type atomic medium under EIT conditions is modified correspondingly to the temporal structure of the RF pulse. The effect is sensitive to the parameters of the pulse which enables measuring the intensity and the spectrum of the RF pulse. The method can be used for storage and lossless transfer of RF information over long distances using optical pulses. 相似文献
10.
O. S. Mishina M. Scherman P. Lombardi J. Ortalo D. Felinto A. S. Sheremet D. V. Kupriyanov J. Laurat E. Giacobino 《Optics and Spectroscopy》2011,111(4):583-588
Electromagnetically induced transparency (EIT) has led to several quantum optics effects such as lasing without inversion
or squeezed light generation. More recently quantum memories based on EIT have been experimentally implemented in different
systems such as alkali metal atoms. In this system the excited state of the optical transition splits into several sublevels
due to the hyperfine interaction. However, most of the theoretical models used to describe the experimental results are based
on a Λ-system with only one excited state. In this article, we present a theoretical model for the Λ-type interaction of two
light, fields and an atomic system with multiple excited state. In particular we show that if the control and probe fields
are orthogonally circularly polarized the EIT effect in an alkali-metal vapor can almost disappears. We also identify the
reasons of this reduction and propose a method to recover the transparency via velocity selective optical pumping. 相似文献
11.
Hong T 《Physical review letters》2003,90(18):183901
We show that a weak probe light beam can form spatial solitons in an electromagnetically induced transparency (EIT) medium composed of four-level atoms and a coupling light field. We find that the coupling light beam can induce a highly controllable nonlinear waveguide and exert very strong effects on the dynamical behavior of the solitons. Hence, in the EIT medium, it is not only possible to produce spatial solitons at very low light intensities but also simultaneously control these solitons by using the coupling-light-induced nonlinear waveguide. 相似文献
12.
We examine electromagnetically induced transparency (EIT) in cascade schemes with N levels and N−1 fields. We show that transparency effects are present when N is odd and that destruction of EIT is present on line centre when N is even. We predict multiple dark resonances in such schemes due to multiphoton EIT effects. By examining atomic rubidium we propose methods of achieving such schemes by use of coupling rf fields into hyperfine levels. 相似文献
13.
Chao Hang 《Physics letters. A》2008,372(17):3129-3135
We investigate possible formation and propagation of localized, shape-preserving nonlinear optical pulse in a resonant, lifetime-broadened four-level tripod atomic system via electromagnetically induced transparency (EIT). We prove both analytically and numerically that although in anomalous dispersion regimes near resonance a superluminal optical soliton may appear, such soliton suffers serious absorption. However, by choosing appropriate parameters to make the system work in normal dispersion regimes and within an EIT transparency window, ultraslow optical solitons with very low light intensity can form and propagate stably in the system. 相似文献
14.
M.G. Payne 《Optics Communications》2007,271(1):269-273
We investigate a coherently prepared cold medium for efficient single-photon inelastic two-wave mixing (ITWM), maximum Fock state entanglement and single photon self-interference. We show the possibility of generating maximally entangled single-photon state, and near 100% conversion efficiency for generating a frequency shifted TWM photon by proper choice of medium length and concentration. In addition, we demonstrate a new type of transparency effect produced by an efficient single photon self-interference, a transparency effect that is very different from the conventional electromagnetically induced transparency (EIT) process. 相似文献
15.
We develop a classical model of the parametric effect of electromagnetically induced transparency (EIT) within the line of resonance absorption of an electromagnetic wave in the medium--an effect initially discovered for a quantum three-level system. On the basis of this model, the EIT effect for electromagnetic waves at frequencies of the electron-cyclotron resonance in a cold plasma is considered. Similar to the analogous quantum scheme, the EIT window in the classical model is characterized by group deceleration of the reference electron-cyclotron wave. 相似文献
16.
We discuss and analyze absorption-dispersion response for the probe field in a typical four-level atomic system with vacuum-induced coherence (VIC) arising from the cross coupling pathways associated with a pair of upper excited hyperfine levels. We find that VIC effect can preserve electromagnetically induced transparency (EIT) by using the detailed numerical simulations based on the density-matrix equations and analytical calculations in the dressed-state picture. We also show that the atomic hyperfine structure cannot be a hindrance to obtaining EIT. 相似文献
17.
WEIHua LIJia-Hua ZHANZhi-Ming PENGJu-Cun 《理论物理通讯》2005,44(1):146-150
We discuss and analyze absorption-dispersion response for the probe field in a typical four-level atomic system with vacuum-induced coherence (VIC) arising from the cross coupling pathways associated with a pair of upper excited hyperfine levels. We find that VIC effect can preserve electromagnetically induced transparency (FIT) by using the detailed numerical simulations based on the density-matrix equations and analytical calculations in the dressed-state picture. We also show that the atomic hyperfine structure cannot be a hindrance to obtaining EIT. 相似文献
18.
We propose an optical sensor that allows site-selective detection of a refractive index change occurring due to any infiltration such as a bio-organism in a porous one-dimensional photonic crystal (PC). We use the electromagnetically induced transparency (EIT) to detect and locate the infiltration. With a localized change in the refractive index, the maximum of the peak EIT transmission shifts, which is determined by tuning the control field frequency. The strong dispersion and the narrowing of the absorption free response associated with EIT within the PC form the basis of such enhanced sensitivity. 相似文献
19.
Electromagnetically induced transparency and quadripartite macroscopic entanglement generated in a ring cavity
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We propose a feasible scheme to generate electromagnetically induced transparency(EIT) and quadripartite macroscopic entanglement in an optomechanical system with one fixed mirror and three movable perfectly reflecting mirrors.We explore the EIT phenomena in this optomechanical system.Results show the appearance of EIT dips in the output field.Moreover,we demonstrate how steady-state quadripartite entanglement can be generated via radiation pressure.We also quantify the bipartite entanglement in each field-mirror subsystem and in the mirror-mirror subsystem.Findings show that a high intensity of entanglement between two subsystems can be achieved. 相似文献
20.
Nonlinear absorption by quantum interference in cold atoms 总被引:1,自引:0,他引:1
We report an experimental observation of third-order nonlinear absorption by quantum interference in (87)Rb atoms cooled and confined in a magneto-optic trap. A coupling laser creates electromagnetically induced transparency (EIT) in a multilevel Rb system in which the third-order nonlinear absorption is enhanced by constructive quantum interference while the linear absorption is inhibited by destructive interference. Our experiment demonstrates the EIT system proposed by Harris and Yamamoto [Phys. Rev. Lett. 81, 3611 (1998)], which absorbs two photons but not one photon in the dressed-state picture. 相似文献