Electromagnetically induced transparency in degenerate two-level systems

The evolution of an electromagnetic wave with slowly varying polarization, which interacts resonantly with the medium formed by degenerate two-level atoms, is studied using the wave function approach under the conditions of electromagnetically induced transparency. It is shown that the amplitude of the wave field propagates at the velocity of light in such a medium. The equation obtained for the polarization parameter has a solution in the form of a simple wave. The breaking length is determined. It is shown that the velocity of propagation of polarization waves may be much smaller than the velocity of light. The proposed approach is common for two-level systems with an arbitrary degeneracy. The case of a system with Zeeman degeneracy is analyzed in detail. The dependence of the velocity of propagation of the polarization structure on the amplitude and polarization is determined for an arbitrary level degeneracy. The evolution of the polarization structure in such a medium is discussed.     

Electromagnetically induced transparency in a three-mode optomechanical system

We study a three-mode double-cavity optomechanical system in which an oscillating membrane of perfect reflection is inserted between two fixed mirrors of partial transmission. We find that electromagnetically induced transparency （EIT） can be realized and controlled in this optomechanical system by adjusting the relative intensity and the relative phase between left-hand and right-hand input （probe and coupling） fields. In particular, one perfect EIT window is seen to occur when the two probe fields are exactly out of phase and the EIT window＇s width is very sensitive to the relative intensity of two coupling fields. Our numerical findings may be extended to achieve optomechanical storage and switching schemes applicable in quantum information processing.     

Electromagnetically induced transparency and electromagnetically induced absorption in Y-type system

The propagation of a probe field through a four-level Y-type atomic system is described in the presence of two additional coherent radiation fields, namely, the control field and the coupling field. An expression for the probe response is derived analytically from the optical Bloch equations under steady state condition to study the absorptive properties of the system under probe field propagation through an ensemble of stationary atoms as well as in a Doppler broadened atomic vapor medium. The most striking result is the conversion of electromagnetically induced transparency(EIT) into electromagnetically induced absorption(EIA) as we start switching from weak probe regime to strong probe regime. The dependence of this conversion on residual Doppler averaging due to wavelength mismatch is also shown by choosing the coupling transition as a Rydberg transition.     

压缩真空中的电磁诱导透明

从主方程出发,通过解析求解密度矩阵非对角元,研究了压缩真空中Λ型三能级原子的电磁诱导透明现象(EIT).研究结果表明:EIT显著地依赖于相干光场的相位、压缩真空的压缩强度和压缩相位.Λ型三能级原子不但有电磁诱导透明和慢光速现象,而且还会表现出对探测光的增益、快光速和反向光速效应;且Λ型三能级原子对探测光场的吸收和增益与探测光强度有关,这与普通真空中不同. 关键词： 压缩真空 电磁诱导透明 增益     

Electromagnetically induced transparency for x rays

Electromagnetically induced transparency is predicted for x rays in laser-dressed neon gas. The x-ray photoabsorption cross section and polarizability near the Ne K edge are calculated using an ab initio theory suitable for optical strong-field problems. The laser wavelength is tuned close to the transition between 1s(-1)3s and 1s(-1)3p approximately 800 nm). The minimum laser intensity required to observe electromagnetically induced transparency is of the order of 10(12) W/cm(2). The ab initio results are discussed in terms of an exactly solvable three-level model. This work opens new opportunities for research with ultrafast x-ray sources.     

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.     

Electromagnetically induced transparency with squeezed vacuum

The squeezed vacuum resonant on the (87)Rb D1 line (probe light) was injected into an optically dense rubidium gas cell with a coherent light (control light). The output probe light maintained its quadrature squeezing within the transparency window caused by the electromagnetically induced transparency (EIT). The results reported here are the first realization of EIT in the full quantum regime.     

Electromagnetically induced acoustic transparency and absorption

The possibility of controlling the passage (from transmission to absorption) of a hypersound through a low-temperature paramagnet using the resonance electromagnetic pumping of lower frequency is substantiated. The effect has a quantum nature and is analogous to (though somewhat different from) the optical phenomenon of electromagnetically induced transparency.     

Electromagnetically induced transparency with Rydberg atoms

We present a theory of electromagnetically induced transparency in a cold ensemble of strongly interacting Rydberg atoms. Long-range interactions between the atoms constrain the medium to behave as a collection of superatoms, each comprising a blockade volume that can accommodate at most one Rydberg excitation. The propagation of a probe field is affected by its two-photon correlations within the blockade distance, which are strongly damped due to low saturation threshold of the superatoms. Our model is computationally very efficient and is in quantitative agreement with the results of the recent experiment of Pritchard et al. [Phys. Rev. Lett. 105, 193603 (2010)].     

Electromagnetically induced transparency in a non-uniform plasma

Electromagnetically induced transparency in a non-uniform plasma is investigated. We discuss the possible frequency ranges in which a weak beam below cutoff can propagate transparently in this plasma with the presence of a strong high frequency field. We also analyze the effect of driving intensity on the frequency range of the probe. Received 3 March 2000 and Received in final form 21 April 2000     

Electromagnetically induced transparency in a molecular gas

The dynamic Stark effect on the as Q(5,4) transition of the 0 → 1 vibrational band of the ν₂ mode of ammonia ¹⁵NH₃ was studied by the method of copropagating waves of radiation of two ¹³CO₂ lasers operating at the R(18)_I line. For waves with mutually orthogonal polarizations, which propagated in a waveguide cell, the intensity of the saturating radiation reached 225 W/cm², and the absorption line of the probing radiation had the form of a two-hump curve with a splitting that was consistent with the Rabi frequency for the ammonia transition being investigated. At the maximum intensity of the saturating radiation, complete transparency was observed at the center of the absorption line of ¹⁵NH₃. When identically polarized saturating and probing waves propagating in a cell at a small angle with respect to each other were used, the splitting was more weakly manifested. The effect of a spatial inhomogeneity of the optical fields on the shape of the line of saturated absorption is discussed.     

Electromagnetically induced transparency in high-temperature magnetoactive plasma

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.     

Electromagnetically induced transparency in semiconductors via biexciton coherence

We report an experimental demonstration and theoretical analysis of electromagnetically induced transparency in a GaAs quantum well, in which the absorption of an exciton resonance is reduced by more than twentyfold. The destructive quantum interference in this scheme is set up by a control pulse that couples to a resonance of biexcitons. These studies illustrate that many-particle interactions, which are inherent in semiconductors and are often detrimental to quantum coherences, can also be harnessed to manipulate these coherences.     

固体介质中的电磁感应透明效应及其应用

电磁感应透明技术不仅能够改变物质对光场的响应，而且能够调控光场本身的性质．文章介绍了电磁感应透明效应的基本原理，电磁感应透明现象在各种固体介质中的实现，比较了这些固体介质的特性，并讨论了由电磁感应透明现象所产生的各种效应及其应用．     

Electromagnetically induced transparency resonances inverted in magnetic field

The phenomenon of electromagnetically induced transparency (EIT) is investigated in a Λ-system of the ⁸⁷Rb D ₁ line in an external transverse magnetic field. Two spectroscopic cells having strongly different values of the relaxation rates γ_rel are used: an Rb cell with antirelaxation coating (L ~ 1 cm) and an Rb nanometric- thin cell (nanocell) with a thickness of the atomic vapor column L = 795 nm. For the EIT in the nanocell, we have the usual EIT resonances characterized by a reduction in the absorption (dark resonance (DR)), whereas for the EIT in the Rb cell with an antirelaxation coating, the resonances demonstrate an increase in the absorption (bright resonances (BR)). We suppose that such an unusual behavior of the EIT resonances (i.e., the reversal of the sign from DR to BR) is caused by the influence of an alignment process. The influence of alignment strongly depends on the configuration of the coupling and probe frequencies as well as on the configuration of the magnetic field.     

Electromagnetically induced transparency based six-wave mixing in a Doppler-broadened folded four-level system

We study phase-conjugate six-wave mixing spectroscopy based on electromagnetically-induced-transparency in a Doppler-broadened folded four-level system.It is found that the six-wave mixing spectrum can be either Doppler-free or very broad,depending on whether the interference between the polarisations of atoms with different velocities is constructive or destructive.To obtain the Doppler-free six-wave mixing spectrum in the folded four-level system,the conditions are more stringent in comparison with those in the cascade and N-type four-level systems.This polarisation interference can be controlled in the presence of a strong coupling field.