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1.
Enhancement of the index of refraction via quantum coherence 总被引:2,自引:0,他引:2
Scully MO 《Physical review letters》1991,67(14):1855-1858
2.
We measure the Kerr-nonlinear index of refraction of a three-level Lambda-type atomic system inside an optical ring cavity. The Kerr nonlinearity is modified and greatly enhanced near atomic resonant conditions for both probe and coupling beams. The Kerr nonlinear coefficient n(2) changes sign when the coupling beam frequency detuning switches sign, which can lead to interesting applications in optical devices such as all-optical switches. 相似文献
3.
This paper attempts a probe into negative refraction without absorption by means of an incoherent pump field and a strong coherent field coupling the dense four-level atomic system. With the application of the incoherent pump field to manipulate the populations in atomic levels and the variable strong coherent field to create quantum coherence, the constraint condition of two equal transition frequencies responding to the probe field in the atomic system isn't required. And these lead to the propagation transparency and strong magnetic response of the probe field, left-handedness with vanishing absorption in the atomic system. However, an excessive coherent field intensity would increase the absorption. 相似文献
4.
5.
Tunable negative refraction without absorption via electromagnetically induced chirality 总被引:1,自引:0,他引:1
We show that negative refraction with minimal absorption can be obtained by means of quantum interference effects similar to electromagnetically induced transparency (EIT). Coupling a magnetic dipole transition coherently with an electric dipole transition leads to electromagnetically induced chirality, which can provide negative refraction without requiring negative permeability and also suppress absorption. This technique allows negative refraction in the optical regime at densities where the magnetic susceptibility is still small and with refraction/absorption ratios that are orders of magnitude larger than those achievable previously. Furthermore, the refractive index can be fine-tuned, which is essential for practical realization of subdiffraction-limit imaging. As with EIT, electromagnetically induced chirality should be applicable to a wide range of systems. 相似文献
6.
Y.-X. Ping B. Zhang Z. Cheng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(1):175-180
The generation of continuous variable entanglement via
atomic coherence in a two-mode three-level cascade atomic system
is discussed according to the entanglement criterion proposed by
Duan et al. [Phys. Rev. Lett. 84, 2722 (2000)].
Atomic coherence between the top and bottom levels is induced with
two photons of a strong external pump field. It shows that
entanglement for the two-mode field in the cavity can be generated
under certain conditions. Moreover, by means of the input-output
theory, we show that the two-mode entanglement could also be
approached at the output. 相似文献
7.
High index of refraction via quantum interference in a three-level system of Er^3+-doped yttrium aluminium garnet crystal 下载免费PDF全文
A simple three-level system is proposed to produce high index of refraction with zero absorption in an Er^3+-doped yttrium aluminium garnet (YAG) crystal, which is achieved for a probe field between the excited state 4I13/2 and ground state 4I15/2 by adjusting a strong coherent driving field between the upper excited state 4I11/2 and 4I15/2. It is found that the changes of the frequency of the coherent driving field and the concentration of Er^3+ ions in the YAG crystal can maximize the index of refraction accompanied by vanishing absorption. This result could be useful for the dispersion compensation in fibre communication, laser particle acceleration, high precision magnetometry and so on. 相似文献
8.
The interaction of a three-level atomic medium with two degenerate sublevels in the ground-state with a coherent radiation field in a ring cavity is investigated. We pay specific attention to atomic coherence within the ground-state doublet, considering separate decay rates for the ground-state coherence and the population difference. In a previous paper we presented the stationary solutions and here we report on self-pulsing solutions. At critical intensities of the input field, the partially stable symmetry-breaking branches give rise to Hopf bifurcations. Furthermore, we observe in a limiting case of the limit cycles solitary solutions. The associated diverging periods show an interesting power law behaviour.Work supported by the Swiss National Science Foundation 相似文献
9.
Multicolor manipulation of negative refraction in a three-level Λ atomic system is theoretically investigated. Based on multicolor coherence, the negative refractive index can be obtained with reduced absorption. The refractive index can also be controlled by changing the sum of the phases of the sidebands in the trichromatic driving fields. By adjusting the sum phase, the refractive index can be varied between negative and positive in two different frequency bands. Furthermore, the frequency band corresponding to the negative refractive index is widened by increasing the intensity and the frequency difference of the trichromatic field. 相似文献
10.
The interaction of a three-level atomic medium with two degenerate sublevels in the ground state with a coherent radiation field in a ring cavity is investigated. We pay specific attention to atomic coherence within the ground-state doublet, and introduce separate decay rates for the ground-state coherence and the population difference. If the atomic density exceeds a critical value, the system exhibits symmetric bistability. In addition, in certain regions of parameter space we find symmetry-breaking branches, yielding optical multistability. We propose physical mechanisms for the symmetric as well as for the symmetry-breaking instability.Work supported by the Swiss National Science Foundation 相似文献
12.
The effects of vacuum-induced coherence (VIC) on the properties of the absorption and gain of the probe field in an equispaced three-level ladder atomic system are investigated. It is found that lasing without inversion (LWI) is remarkably enhanced due to the effect of VIC in the case of the small incoherent pump rate. 相似文献
13.
A three level scheme interacting with three laser fields is considered. It is found that two competing processes contribute to the absorption/dispersion on a particular transition: (i) one-photon processes governed by the field applied to that transition, and (ii) two-photon processes governed by the two laser fields applied to two other transitions. Interference between the two processes can be both constructive and destructive. It is shown that the net absorption/gain and dispersion can be controlled by the relative phases of the laser fields. 相似文献
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15.
基于两单光子过程的相位共轭二阶极化干涉,从理论上研究了V型三能级系统在阿秒量级的对称和频极化拍频(SFPB),考虑了抽运光束为窄带线宽或宽带线宽的情形,发现测得的信号对任意带宽的马可夫随机光场的统计特征非常敏感,其在测量偶极禁界跃迁两激发态之间的能级和时并不受激光线宽的限制,仅取决于光学跃迁均匀增宽,而且可以得到消除多普勒增宽的测量精度.在窄带情形下,场关联对SFPB信号影响很弱.在宽带情形下,SFPB信号表现出共振 非共振交叉关联.SFPB作为一种阿秒超快调制过程,从理论上说它可以扩展到任何和频能级系统.
关键词:
阿秒
和频
极化拍
二阶相干 相似文献
16.
An optical atomic clock scheme is proposed that utilizes two lasers to establish coherent coupling between the 5s2 1S0 ground state of 88Sr and the first excited state, 5s5p 3P0. The coupling is mediated by the broad 5s5p 1P1 state, exploiting the phenomenon of electromagnetically induced transparency. The effective linewidth of the clock transition can be chosen at will by adjusting the laser intensity. By trapping the 88Sr atoms in an optical lattice, long interaction times with the two lasers are ensured; Doppler and recoil effects are eliminated. Based on a careful analysis of systematic errors, a clock accuracy of better than 2 x 10(-17) is expected. 相似文献
17.
We report significant enhancement of the nonlinear Faraday rotation in optically thick Rb vapor. Polarization rotation angles as large as 10 rad were observed for what is believed to be the first time for sub-Gauss magnetic fields. The use of this effect for high-precision magnetometry is also discussed. 相似文献
18.
A three-level ∧-model atomic system with incoherent pumping is proposed to achieve high refractive index without absorption. In this kind of model, two lower levels are near-degenerate levels. It is found that high refractive index accompanied by vanishing absorption can be always accomplished by adjusting some related parameters. Although probe field is very weak, the SGC effect is prominent in the presence of incoherent pumping. 相似文献
19.
K. Mathan Kumar A. John Peter C. W. Lee 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,84(3):431-438
Electronic energies of an exciton confined in a strained
Zn1−x
Cd
x
Se/ZnSe quantum dot have
been computed as a function of dot radius with various Cd content. Calculations have been
performed using Bessel function as an orthonormal basis for different confinement
potentials of barrier height considering the internal electric field induced by the
spontaneous and piezoelectric polarizations. The optical absorption coefficients and the
refractive index changes between the ground state (L = 0) and the first
excited state (L = 1) are investigated. It is found that the optical
properties in the strained ZnCdSe/ZnSe quantum dot are strongly affected by the
confinement potentials and the dot radii. The intensity of the total absorption spectra
increases for the transition between higher levels. The obtained optical nonlinearity
brings out the fact that it should be considered in calculating the optical properties in
low dimensional semiconductors especially in quantum dots. 相似文献
20.
N. K. Solovarov 《Journal of Experimental and Theoretical Physics》2008,106(6):1033-1044
The correlated dynamics of a three-level atom resonantly coupled to an electromagnetic cavity field is calculated (Λ, V, and L models). A diagrammatic representation of quantum dynamics is proposed for these models. As an example, Λ-atom dynamics is examined to demonstrate how the use of conventional von Neumann’s reduction leads to internal decoherence (disentanglement-induced decoherence) and to the absence of atomic coherence under multiphoton excitation. The predicted absence of atomic coherence is inconsistent with characteristics of an experimentally observed atom-photon entangled state. It is shown that the correlated reduction of a composite quantum system proposed in [18] qualitatively predicts the occurrence and evolution of atomic coherence under multiphoton excitation if a seed coherence is introduced into any subsystem (the atom or a cavity mode). 相似文献