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We propose a scheme for controllably entangling the ground states of five-state W-type atoms confined in a cavity and realizing swap gate and phase gate operations. In this scheme the cavity is only virtually excited and the atomic excited states are almost not occupied, so the produced entangled states and quantum logic operations are very robust against the cavity decay and atomic spontaneous emission. 相似文献
3.
Optical responses of dilute anisotropic composites:numerical calculations via Green‘s function formalism 下载免费PDF全文
We investigate the linear and nonlinear optical responses of dilute anisotropic networks using Green's function formalism [Gu Y et al 1999 Phys. Rev. B 59 12847]. For different applied fields, numerical calculations indicate that a large third-order nonlinear enhancement and a broad infrared absorption arise from the geometric anisotropy. We also show the overlap and separation between the absorption peak and nonlinear enhancement peak when the applied field is parallel and perpendicular to the anisotropy, respectively. The results can be understood in terms of the inverse participation ratios with q=2 and the spectral distribution of optical responses. 相似文献
4.
Absorption and refraction of the inner transition F2\leftrightarrow
F3 of the closed four level N-type atom have been investigated under a
weak field. The outer transitions F1\leftrightarrow F3 and
F2\leftrightarrow F4 are resonantly interacted with drive field with
frequency \omegac and Rabi frequency \Omegac, and saturation
field with \Omegas and \Omegas, respectively. For the suitable Rabi
frequencies \Omegac and \Omegas, we obtain
the Mollow absorption
spectrum of probe field. The reason is that the drive field excites the atom
to the upper level Fc and simultaneously the saturation field takes
the atom out of the lower level F2, leading to the stimulated emission.
Meanwhile, due to the dynamic energy splitting induced by the drive and
saturation fields, the two- and four-peaked absorption spectra are observed.
At the zero off-resonance detuning of probe field, we also find the transfer
of dispersion from negative to positive with an increment of \Omegas.
Finally, the refractive index enhancement is predicted for a wide spectral
region. 相似文献
5.
Controlling optical responses through local dielectric resonance in nanometre metallic clusters 下载免费PDF全文
Optical responses in dilute composites are controlled through the
local dielectric resonance of metallic clusters. We consider two
located metallic clusters close to each other with admittances
\varepsilon1 and \varepsilon2. Through varying the
difference admittance ratio \eta [ = (\varepsilon2- \varepsilon
0) / (\varepsilon1- \varepsilon0)], we find that their
optical responses are determined by the local resonance. There is a
blueshift of absorption peaks with the increase of \eta.
Simultaneously, it is known that the absorption peaks will be
redshifted by enlarging the cluster size. By adjusting the
nano-metallic cluster geometry, size and admittances, we can control
the positions and intensities of absorption peaks effectively. We
have also deduced the effective linear optical responses of
three-component composites \varepsilone= \varepsilon0
\bigl(1 + \sumn=1^{ns} [(\gamman2+ \eta \gamman2)/({\varepsilon0(s - sn))]} \bigr), and the sum
rule of cross sections: \sumn=1^{ns} {(\gamman2+
\eta \gamman2 ) = Nh1+ Nh2, where Nh1and
Nh2 are the numbers of \varepsilon1 and \varepsilon2
bonds along the electric field, respectively. These results may be
beneficial to the study of surface plasmon resonances on a nanometre
scale. 相似文献
6.
Green's function formalism in semi-infinite composites: an investigation of local field distribution 下载免费PDF全文
In the resonant composites, the formerly developed Green's function formalism (GFF) can be used to compute the local field distribution near resonance. In this paper, we extend the GFF in the infinite network to the semi-infinite networks by the method of image. Using the formalism, we investigate the local field distribution near resonance for the impurity clusters with admittance ε_0 embedded in one semi-infinite network with ε_1. With varying the admittance ε_2 of another semi-infinite network, we find that the local fields in the boundary experience great changes, especially at ε_2=-ε_1. The existence of the boundary enhances the localization of the fields within and around the metallic clusters. Therefore, the intensity of local field is influenced by the arrangement of impurity metallic bonds and its distance from the boundary. 相似文献
7.
Surface plasmon polariton and mode transformation in a nanoscale lossy metallic cylindrical cable 总被引:1,自引:0,他引:1 下载免费PDF全文
A theoretical investigation on the surface plasmon polariton in a gold cylindrical nanocable is presented. By solving a complete set of Maxwell's equations in the nanocable (with a 50 nm radius gold nanocore, 10-300 nm silica layer, and 30-200nm gold nanocladding), the dispersion relations on the optical frequency and on the silica thickness are discussed. When the silica thickness varies from 50 to 250 nm, at a fixed waveleltgth, the strong coupling between the gold nanocore and the nanocladding leads to a symmetric-like surface mode and an antisymmetric-like surface mode in the nanocable. The transformation between the surface mode and the waveguide mode in this structure is also investigated. The results will be helpful for understanding the surface waves in the subwavelength structures. 相似文献
8.
Enhancing light–matter interaction in cavity quantum electrodynamics has aroused widespread interests in on-chip quantum information processing. Here, we propose a hybrid nanotoroid–nanowire system to enhance photon–exciton interaction. A nanoscale gap is formed by placing a dielectric nanowire close to a dielectric nanotoroid, where the coupling coefficient between photon and emitter can achieve 5.55 times of that without nanogap. Meanwhile, the cavity loss and spontaneous emission of the emitter will remain at a small value to guarantee the realization of strong coupling. The method might hold promise for the research of nanophotonics,quantum optics, and novel optical devices. 相似文献
9.
Effect of relaxation rate on population distribution, EIT and refraction in Λ and V systems 下载免费PDF全文
In the three-level Λ-type and V-type systems, we find that the same pump-effect parameter R\left(=\dfrac{2|V_{c}|^{2}γ}{(ω_{ac}-ω_{c})^{2}+γ^{2}}\right) determines the population distributions, while the probe field leads to population fluctuations near the absorption peaks. With the increasing of the relaxation rate γ, the population distributions are shifted and their fluctuation amplitudes decrease. At the same time the electromagnetically induced transparency window becomes a broadened absorption peak, and the dispersion at the zero probe detuning changes from positive to negative. Large population fluctuation and non-fluctuation observed in different systems are attributed to the different relaxation rates. 相似文献
10.
We investigate the quantum coherence effects of a cycling transition Fe=0(←→)Fg=1, which is saturated and probed by the circular polarized fields, and is subject to a linearly polarized field and a magnetic field.Saturation field is applied in the case of the maximum coherence between the drive Rabi frequency and magnetic field, corresponding to the electromagnetically induced absorption (EIA) with negative dispersion found by Gu et al.In a small saturation Rabi frequency, the holes are burned in two Autler-Towns peaks outside two symmetric electromagnetically induced transparency (EIT) windows due to the two-photon resonance.When the saturation Rabi frequency is comparable with the drive Rabi frequency, the holes caused by the coherent population oscillation appear in the EIA spectrum.Continuing to increase the saturation Rabi frequency, we observe several emission peaks due to the Mollow absorption effects.Simultaneously, four-wave mixing (FWM) effects in this process are discussed.In the picture of dressed states, we explain the multi-peaks of quantum efficiency of FWM in terms of the multi-photon resonance conditions.We also find a good agreement between the absorption peaks and the FMW peaks.Finally, whenever EIA, EIT, or Mollow absorption happens, the dispersion at the pump-probe detuning center is kept to be negative with increasing the saturation Rabi frequency.It means that this point is suitable to perform the superluminal light propagation experiments. 相似文献