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1.
Effect of atomic initial phase difference on spontaneous emission of an atom embedded in photonic crystal
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<正>We investigate the effect of initial phase difference between the two excited states of a V-type three-level atom on its steady state behaviour of spontaneous emission.A modified density of modes is introduced to calculate the spontaneous emission spectra in photonic crystal.Spectra in free space are also shown to compare with that in photonic crystal with different relative positions of the excited levels from upper band-edge frequency.It is found that the initial phase difference plays an important role in the quantum interference property between the two decay channels.For a zero initial phase,destructive property is presented in the spectra.With the increase of initial phase difference,quantum interference between the two decay channels from upper levels to ground level turns to be constructive.Furthermore, we give an interpretation for the property of these spectra. 相似文献
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A novel atom configuration is proposed for a giant Kerr nonlinearity in zero linear and nonlinear probe absorption. It is shown that without coherent control field and just by quantum interference of spontaneous emission, a giant Kerr nonlinearity can be obtained. 相似文献
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We study the coherent control of spontaneous emission of a double-driven four-level atom embedded in photonic crystals. Combined effect of different relative locations between the upper band edge and the two upper levels and the phase of microwave coupling field is discussed. It is shown that quantum interference effect such as laser-induced dark line depends strongly on the phase of microwave field. 相似文献
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S. Roshan Entezar 《Optics Communications》2009,282(6):1171-1174
In this paper, the effect of quantum interference on the entanglement of a driven V-type three-level atom and its spontaneous emission field was investigated by using the quantum entropy. The results indicate that, in the absence of quantum interference the atom and its spontaneous emission field are always entangled at the steady-state. But, in the presence of full quantum interference their steady-state entanglement depends on the atomic parameters. Specifically, with appropriate atomic parameters they can be entangled or disentangled at the steady-state. We realized that the steady-state entanglement is due to completely destructive nature of quantum interference. On the contrary, the steady-state disentanglement is due to instructive nature of quantum interference. 相似文献
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Ning Ou-Yang Jun-Li Wang Ping Zhang Hai Pang 《International Journal of Theoretical Physics》2009,48(3):743-754
Based on the result of cavity quantum electrodynamics, we suggest a method, in which the Fabry-Perot cavity or the confocal
cavity is replaced by a waveguide with the size comparable to the wavelength of the photon, to reduce decoherence caused by
spontaneous emission in quantum information processing, especially in the realization of quantum computation. Since a waveguide
has a lowest cutoff frequency while a Fabry-Perot cavity or a confocal cavity has none, the spontaneous emission of excited
atoms will be forbidden in an ideal waveguide with an appropriate size. To avoid the influence of the non-ideal conducting
walls on the atom in a realistic waveguide, which will lead to decoherence, we suggest that the waveguide should be coated
by a thin film of transparent insulating medium. In our method, the quantum information is represented by a multi-level atom
or molecule; any two of its levels can be used to represent a qubit in principle. Our method greatly extends the choice of
the material to be used in the realization of quantum computation, and it can be used in most schemes to reduce the decoherence
caused by spontaneous emission. 相似文献
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The time evaluation of quantum entropy in a four-level N-type atomic system is theoretically investigated. Quantum entanglement of the atom and its spontaneous emission fields is then discussed via quantum entropy. It is found that the degree of entanglement can be increased by the quantum interference induced by spontaneous emission. The phase dependence of the atom-field entanglement is also presented. 相似文献
7.
用全量子理论研究二能级原子单模腔耦合系统,通过理论推导和数值计算得出系统的自发辐射光谱和平均粒子数密度.共振时腔与原子的发射光谱在强耦合与弱耦合区域有所不同,腔发射光谱分裂只出现于强耦合区域,而原子发射光谱由于腔感应透明效应在弱耦合区域出现了缺口.本文系统地研究了原子与腔在失谐时的发射光谱,在好腔机理(腔线宽小于原子线宽g)原子与腔即使在大失谐时腔发射出腔频率的光子,这给当前实验上困惑的特性提供了一个理论依据.为了给腔感应透明效应一个新的深入了解,还研究了原子与腔平均粒子数密度随时间的演化,以及平均粒子数密度与光强度之间的关系.
关键词:
自发辐射
强耦合
腔感应透明
好腔机理 相似文献
8.
研究了单模光腔中两组分玻色-爱因斯坦凝聚的基态性质和相关的量子相变.通过利用自旋相干态变换将等效赝自旋哈密顿算符对角化并求得基态能量泛函.基态能量泛函对其经典场变量进行变分并取极小值,得到光子数解和相边界曲线.通过稳定性讨论发现系统除了出现正常相和超辐射相之外,还得到了多稳的宏观量子态;受激辐射来自于原子数反转的集体态,单组分的Dicke系统中并没有此现象;受激辐射只能从一组分的原子中产生,而另外的仍保持在普通超辐射状态.通过调整相关的原子-场耦合强度和频率失谐,超辐射和受激辐射态的顺序可以在原子的两个组分之间互换. 相似文献
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We introduce a modified density of modes to investigate the spontaneous emission spectrum of a three-level V-type atom in photonic crystal using Laplace transform. The atom’s steady state behavior of spontaneous emission is treated for different locations of the upper band-edge frequency. Furthermore; the influence of quantum interference between the two decay channels on spontaneous emission is discussed. 相似文献
12.
The retarded spontaneous emission (SpE) process of a two-level atom embedded in realistic one dimensional photonic crystals (1DPC) is investigated with the quantum nonperturbative theory. The atomic transient decay is divided into two processes: the first comes from the natural decay to free space and the second is induced by the reflected field emitted from the atom itself. Due to the multi-reflection in the multi-layer structure, the correct delay time of the induced decay process is hard to calculate in the usual ways. However with the special but practical 1DPC provided, we give the analytic result of the atomic dynamic decay in 1DPC. Our result gives a clear picture to show the process which the atom feels the surrounding. 相似文献
13.
A. M. Basharov 《Journal of Experimental and Theoretical Physics》2018,126(3):310-320
The Markov model of spontaneous emission of an atom localized in a spatial region with a broadband electromagnetic field with zero photon density is considered in the conditions of coupling of the electromagnetic field with the broadband field of a neighboring space. The evolution operator of the system and the kinetic equation for the atom are obtained. It is shown that the field coupling constant affects the rate of spontaneous emission of the atom, but is not manifested in the atomic frequency shift. The analytic expression for the radiative decay constant for the atom is found to be analogous in a certain sense to the expression for the decay constant for a singly excited localized ensemble of identical atoms in the conditions when the effect of stabilization of its excited state by the Stark interaction with the vacuum broadband electromagnetic field is manifested. The model is formulated based on quantum stochastic differential equations of the non- Wiener type and the generalized algebra of the Ito differential of quantum random processes. 相似文献
14.
We have studied the spontaneous emission behaviour in a five-level M-type atom driven by two optical fields of high frequencies and a microwave field of low-frequency. In absence of non-orthogonal decaying pathways, due to microwave field induced low-frequency coherence, the present model produces the emission spectrum resembling that of a three-level system controlled by the effect of vacuum induced decay-interference. For particular sets of values of the Rabi frequencies of the resonant coherent fields, the system exhibits quantum interference induced switching effect. By using this model, we have shown that the phenomenon of narrowing can be induced in the emission peaks without any detuning and phase control of the coherent fields. With the increase in the value of the Rabi frequency of the microwave field, this feature will be accompanied by the peak-compression and -repulsion effect. When the coherent fields are far from resonance, the appearance of the single-photon and the two-photon peaks in the emission spectrum can be easily controlled by changing the value of the Rabi frequency of the microwave field. We have shown the appearance of multiple dark regions in the emission line shape for equal as well as unequal decay rates of two emission pathways. Other interesting phenomena like elimination, enhancement and suppression of spectral line are also explored in various resonant and non-resonant cases. 相似文献
15.
量子计算机存储单元的相干脱散,破坏量子态中的信息,是量子计算机难以实现的主要原因之一.本文在Rzazewski的工作基础上,针对两能级原子构造的存储单元,研究自发发射对存储单元相干脱散的影响
关键词: 相似文献
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Xin Yang Dong Yan Qianqian Bao Yan Zhang Cuili Cui 《Central European Journal of Physics》2014,12(12):813-821
Owing to interference induced by spontaneous emission, the density-matrix equations in a three-level Λ-type system have an additional coherence term, which plays a critical role in modulating the inversionless gain and electromagnetically induced transparency effect. In addition, it is shown that spontaneously generated coherence (SGC) has an effect on the entanglement between an atom and a photon of the coupling laser field by calculating the degree of entanglement (DEM) of the atomic system. In this paper, we investigate the influence of the SGC effect on atom-photon entanglement in a Λ-type system, which generally remains a high entangled state. When an incoherent pump source is introduced, we find that the SGC effect could exert considerable influence on the atom reduced entropy under certain conditions for both transient and steady states. More interestingly, such an incoherent pump field could actively affect the short-time dynamic behaviors of the transient quantum entangled state at a certain range of pump rate as a typical coherent case. 相似文献
19.
The control of spontaneous emission from an radio-frequency (RF)-driven five-level atom embedded in a three-dimensional photonic
crystal is investigated by considering the anisotropic double-band photonic-band-gap (PBG) reservoir. It is shown that, due
to the coexistence of the PBG and the quantum interference effect induced by the RF-driven field, some interesting features,
such as the spectral-line narrowing, the spectral-line enhancement, the spectral-line suppression and the occurrence of a
dark line in spontaneous emission, can be realized by adjusting system parameters under the experimentally available parameter
conditions. The proposed scheme can be achieved by use of an RF-driven field into hyperfine levels in rubidium atom confined
in a photonic crystal. These theoretical investigations may provide more degrees of freedom to vary the spontaneous emission. 相似文献