In quantum optics, it is well known that Electromagnetically Induced Transparency can make light slowed down, even to zero. It also is an important field in nowadays research in quantum optics. This article develops a new way to study the phenomenon by classical electrodynamics. It solves the important problem by classical way instead of quantum way. Moreover, it fits the results they have got in the recent experiments. At the beginning, we get the refractive index by classical electrodynamics, then we get the relation between atomic polarizability and light frequency. At last, we could get the relation between refractive index and wave velocity. And the data from theoretical deduce are the same as them in the recent experiments.
In quantum optics, it is well known that Electromagnetically Induced Transparency can make light slowed down, even to zero. It also is an important field in nowadays research in quantum optics. This article develops a new way to study the phenomenon by classical electrodynamics. It solves the important problem by classical way instead of quantum way. Moreover, it fits the results they have got in the recent experiments. At the beginning, we get the refractive index by classical electrodynamics, then we get the relation between atomic polarizability and light frequency. At last, we could get the relation between refractive index and wave velocity. And the data from theoretical deduce are the same as them in the recent experiments.
Despite the importance of quantum interference and coherent population trapping to the theory of electromagnetically induced transparency (EIT), it is shown that the recent experiments which slow down and even stop a light pulse in a dielectric really rely on a linear, refractive index type theory. From this point of view and in considerable contrast, the experiment on degenerate self-induced transparency (SIT) done 27 years ago which slowed down an optical pulse (in principle to zero velocity) was based on an intrinsically nonlinear (soliton type) theory. In quantum mechanical terms both theories are developed at the level of expectation values only and at this level the two different theories come together in terms of the storage and retrieval of information. In the Appendix we analyse the nature of this information in terms of the quantum equations governing linear EIT and nonlinear SIT.
It is now well understood that the characteristics of a nonlinear optical process are the result of the interplay of the linear and nonlinear susceptibilities. In general, as an atomic transition to the ground state is approached, the nonlinear susceptibility is resonantly enhanced, but, at the same time, the media exhibits a rapidly increasing refractive index and becomes opaque. During the last several years we have shown how electromagnetically induced transparency (EIT) may be used to dramatically solve this problem.
The two-level atom can, for good reason, be considered the basic material structure for the study of quantum optics [1]. The two-level atom has played a fundamental role in studies of physical processes, including self-induced transparency (SIT), photon echoes, optical nutation, saturation spectroscopy, and, most recently, slow- and fast-light research. This latter field has recently been the subject of great activity, as researchers have learned how to utilize various physical processes to exert control over the velocity of propagation of light pulses through material systems [2]. This interest stems both from the intellectual intrigue in situations in which the velocity of light can be speeded up or slowed down by many orders of magnitude and the promise that such techniques might be useful for applications in fields such as telecommunications and optical computing [3‐6]. Most of the recent work in this field has made use of the process of electromagnetically induced transparency (EIT) to induce a narrow transparency region in an otherwise highly absorbing optical material [7, 8]. The rapid variation of the refractive index n associated with this transparency window then leads to a strong modification of the group velocity n g in accordance with the standard relation
Abstract Electromagnetically induced transparency (EIT) stems from a quantum system, where an opaque atomic medium appears the narrow transparent state within a wide absorption area. This phenomenon can be achieved by quantum interference of pumping light and detecting light at different energy levels of transitions. In the generation process of EIT effect, in addition to transparent state, the atomic medium is usually accompanied with a strong dispersion effect, which will bright about a significant reduction of light velocity, thus realizing many important applications, such as slow light propagations. Although the EIT effect has many important applications, its application scenarios are greatly limited due to the fact that EIT realization usually requires specific and complicated conditions, such as refrigeration temperature, high intensity laser, etc. Recently, the analogue of EIT effect in metamaterial has attracted increasing attentions due to its advantages such as controllable room temperature and large operating bandwidth. Metamaterial analogue of EIT effect has become a new research focus. In this article, we review current research progresses on EIT metamaterials. Firstly, we describe the theoretical models for analyzing EIT metamaterials, including the mechanical oscillator model and the equivalent circuit model. Then, we describe the simulations, designs and experiments of passive EIT metamaterials with fixed structures and active EIT metamaterials with tunable elements. Furthermore, the applications of EIT metamaterials in the areas of slow lights, sensings, absorptions and other fields are also reviewed. Finally, the possible directions and key issues of future EIT metamaterial researches are prospected.
We prove that it is possible to freeze a light pulse (i.e., to bring it to a full stop) or even to make its group velocity negative in a coherently driven Doppler broadened atomic medium via electromagnetically induced transparency (EIT). This remarkable phenomenon of the ultraslow EIT polariton is based on the spatial dispersion of the refraction index n(omega,k), i.e., its wave number dependence, which is due to atomic motion and provides a negative contribution to the group velocity. This is related to, but qualitatively different from, the recently observed light slowing caused by large temporal (frequency) dispersion.
Electromagnetically induced transparency (EIT) is the fact that a strong field (called control) resonant with an atomic transition, can make the atomic medium transparent for another field (called signal) resonant with a transition sharing the same excited state. Introduced theoretically and first observed by Harris and co-workers, it has since then given rise to important applications. Significantly, EIT led to the demonstration of slow-light and opened the way to the development of a reversible quantum memory for light, which is a major challenge for quantum information networking.