共查询到20条相似文献,搜索用时 174 毫秒
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对相干态与级联三能级原子相互作用过程中原子与场的动力学特性 总被引:5,自引:1,他引:4
研究对相干态与级联三能原子相互作用的动力学特性。结果表明,无论场模与原子的中间能级是否失谐,拉比振荡和互关联函数的时间演化都呈现崩溃与回复现象,但崩溃的持续时间随失谐量的增加而迅速延长,且两模之间随时间的演化即出现关联也出现反关联。 相似文献
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在克尔媒质中原子和光场的量子信息保真度 总被引:3,自引:0,他引:3
讨论了在克尔媒质中原子与光场相互作用及拉曼相互作用时原子、光场和整个系统的量子信息保真度的时间演化过程。研究光场的光强、失谐量及克尔参量对保真度的影响。研究表明,当拉比振荡频率与光子数成正比时保真度表现出周期性的等幅振荡。光强的增加将使保真度下降,失谐量的增加会提高保真度,克尔媒质也对保真度的演化产生影响。失谐量为0,克尔参量为0.5g时以及在能级简并的拉曼过程中保真度表现出很规则的等幅周期振荡。 相似文献
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提出了一种采用两套超大红失谐消逝波干涉和一束蓝失谐消逝波光场来实现原子二维表面微光阱阵列和原子有效强度梯度冷却的新方案,得到了二维表面微光阱阵列的光强分布和光学势分布.研究发现,二维表面微光阱阵列中微光阱的光学势能够有效地囚禁从标准磁光阱中释放的冷原子,并且被囚禁的冷原子能在蓝失谐消逝波光场的作用下产生有效的强度梯度Sisyphus冷却,对87Rb原子而言,原子温度能被冷却到2.56μK.该方案在冷原子物理、原子光学和量子光学领域中有着广阔的应用前景.
关键词:
消逝波干涉
微光阱阵列
原子囚禁
强度梯度冷却 相似文献
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若干参数对瞬态电磁感应透明的影响 总被引:3,自引:0,他引:3
研究了原子梯形三能级系统的瞬态电磁感应透明特性,分析了系统各种参数,诸如瞬态作用时间、泵浦场和探测场的拉比频率、激光线宽及消相碰撞等因素对瞬态电磁感应透明的影响。结果表明:在不考虑激光线宽及消相碰撞时,探测场的吸收随时间在零吸收附近作类似于阻尼减幅振荡,系统可实现无反转放大;随着泵浦场的拉比频率的减小及上能级驰豫速率的增大,感应透明将减弱。在考虑到激光线宽及消相碰撞等非相干因素时,对于一定的瞬态作用时间,感应透明将随着探测场拉比频率的增大而减弱。 相似文献
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We investigate the interaction of a multilevel atom with a short femtosecond optical pulse beyond the scope of the rotating-wave approximation. We consider the behavior of a three-level atom under the action of two optical pulses resonant with two allowed transitions and a two-level atom under the action of a resonant optical pulse. It is shown that the imaginary part of the off-diagonal elements of the density matrix oscillates with high frequency due to the counter-rotating terms. It is shown also that an effective time-dependent addition to the Rabi frequency exists, which is of importance for ultrashort optical pulses. 相似文献
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Carrier shock and frequency conversion of a few—cycle pulse laser propagating in a non—resonant two—level atom medium
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We have studied the spectral behaviour of few-cycle soliton pulses in a non-resonant two-level atom medium by solving the full Maxwell-Bloch equations. It is demonstrated further that the carrier effects play an important role in the propagation of the few-cycle pulse laser. When the frequency detuning is not very large, both the population distribution and the refractive index of the medium follow the oscillatory carrier field instantaneously; in this case, carrier-wave compression or carrier shock occurs, and a supercontinuum broader than that in the resonant medium may be generated. When the frequency detuning is large, the carrier shock is weak and the spectrum is not continuous, only showing an odd harmonic radiation. 相似文献
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The general expressions of the average dissipative and dipole forces acting on a A-configuration three-level atom in an arbitrary light field are derived by means of the optical Bloch equations based on the atomic density matrix elements, and the general properties of the average dissipative and dipole forces on a three-level atom in the linearly-polarized high-order Bessel beams (HBBs) are analysed. We find a resonant property (with two resonant peaks) of the dissipative force and a non-resonant property (with two pairs of non-resonant peaks) of the dipole force on the three-level atom, which are completely different from those on the two-level atom. Meanwhile we find a saturation effect of the average dissipative force in the HBB, which comes from the saturation of the upper-level population. Our study shows that the general expressions of the average dissipative and dipole forces on the three-level atom will be simplified to those of the two-level atom under the approximation of large detuning. Finally, we study the axial and azimuthal Doppler cooling of atoms in ID optical molasses composed of two counter-propagating HBBs and discuss the azimuthal influence of the HBB on the Doppler cooling limit. We also find that the Doppler limit of atoms in the molasses HBB is slightly below the conventional Doppler limit of hГ/(2kB) due to the orbital angular momentum lh of the HBB. 相似文献
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The possibility of efficient terahertz generation via optical rectification in electro-optic crystal doped with the two-level resonant impurities is demonstrated. Under conditions of the self-induced transparency regime the laser pulses slows down to achieve the phase matching condition. The terahertz generation is accompanied by periodic modulation and spectral deformation of the laser pulse. The most efficient generation occurs under condition of small negative detuning from the resonant frequency of the two-level system. 相似文献
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We introduce a scheme for creating continuous variable entanglement between an atomic beam and an optical field, by using squeezed light to outcouple atoms from a Bose-Einstein condensate via a Raman transition. We model the full multimode dynamics of the atom laser beam and the squeezed optical field and show that, with appropriate two-photon detuning and two-photon Rabi frequency, the transmitted light is entangled in amplitude and phase with the outcoupled atom laser beam. The degree of entanglement is controllable via changes in the two-photon Rabi frequency of the outcoupling process. 相似文献
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Adiabatic passage induced by a frequency-chirped laser pulse in four-level ladder systems is investigated. Two different strategies for efficient population transfer (intuitive and counterintuitive laser pulse) are analyzed. For the larger detuning, the four-level ladder system can be reduced to a two-level system with which we are familiar. For the smaller detuning, the main conditions for realization of population transfer are the following: the width of the transform-limited laser pulse envelope frequency spectrum (without chirp) must be smaller and the peak Rabi frequency of the pulse must be larger than the detuning ε21 and ε21∼ε32 in the case of the three-photon resonance. With this laser pulse, it is possible to achieve complete population via the intermediate levels by three successive adiabatic passages. Complete inversion is also obtained by a counterintuitive direction of the frequency sweep. 相似文献
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We demonstrate coherent control of the optical transition of single nitrogen-vacancy defect centers in diamond. On applying short resonant laser pulses, we observe optical Rabi oscillations with a half period as short as 1 ns, an order of magnitude shorter than the spontaneous emission time. By studying the decay of Rabi oscillations, we find that the decoherence is dominated by laser-induced spectral jumps. By using a low-power probe pulse as a detuning sensor and applying postselection, we demonstrate that spectral diffusion can be overcome in this system to generate coherent photons. 相似文献
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We present analytic solutions of optical Bloch equations. We found that the solutions exhibit two different types of the behavior: one is oscillatory, and the other is a simple decay. The boundary dividing the two different types of solutions is exactly calculated in a two-dimensional space of the laser detuning and Rabi frequency. We also obtained simple analytic solutions for special conditions. 相似文献