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从多能级原子与多模光场的相互作用哈密顿量出发,导出了Λ型三能级原子与双模光场的相互作用哈密顿量。在大失谐条件下将其化成等效的二能级形式-双模喇曼耦合模型。提出了该模型的一个改进型等效哈密顿量。该哈密顿量由两部分构成:一部为通常所谓的等效哈密顿量,另一部分描述原子能级的动态斯塔克移动。研究表明,在双模喇曼耦合模型的研究中,只考虑前者是不够的,还必须考虑后者。最后,我们研究了该系统中原子的动力学行为,发现崩塌-复苏的数目、崩塌时间和复苏时间均呈现新的特性。 相似文献
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本文采用Λ型三能级原子模型,其两个低能态之间的耦极跃迁是被禁戒的,考虑两个此种原子与一双模量子腔场的喇曼耦合模型,在双光子共振和单光子大失谐条件下,绝热消去了系统哈密顿量中原子的激发态,而研究两低能态间的纠缠。 相似文献
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用量子的方法,退关联近似,获得了三能级简并双光子双稳态方程。所得结果与实验相符合。指出用双光子矢量模型方法处理的缺点以及它与实验不符的原因。
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本文研究了在Kerr型介质腔中经双光子辐射的二能级级联型原子和三能级级联型原子的动力学,在初始可干态下分别用有效效哈密顿量方法(含Stark位移项)和全哈密顿量方法获得精确解,继而比较了原子的粒子数反转,光子统计分布,聚束与反聚束特性以及光场压缩性特性的数值结果,由此证明了在非线性介质的条件下,两种方法所获得结果类同,差异很小。 相似文献
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An effective Hamiltonian for the two-level model is derived from the microscopic Hamiltonian of a three-level atom in a configuration, interacting through two-photon transitions with a lightfield. The effective Hamiltonian includes a term describing the optical Stark shift. With this effective Hamiltonian, we study the steady-state equation and the squeezing spectrum from a cavity field mode interacting with an ensemble of three level configuration atoms by a two-photon transition. It is shown that the inclusion of optical Stark shift brings about changes in drift and diffusion coefficients as well as additional nonzero correlations between the stochastic forces. As a result, although qualitative features remain unaltered, quantitative changes both in the transmission characteristics and the squeezing spectrum are significant. 相似文献
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It is shown that the system of a three-level atom coupled with two modes of quantized cavity fields in the V-configuration with arbitrary detunings can be exactly reduced to a two-level system with a nonsingular effective coupling which depends nonlinearly on the intensity of the two cavity fields. By performing a unitary transformation, we obtain an exact transformed Hamiltonian in which one of the three levels is decoupled for all values of the detunings including the zero-detuning. We also present the analytical expressions of energy eigenvdues and eigenvectors, evolution operator, time-varying atomic inversion operator and photon number operators of the two modes for the effective two-level model. 相似文献
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A. M. Basharov 《Optics and Spectroscopy》2012,112(3):342-351
In the effective Hamiltonian representation, we have obtained a quantum stochastic differential equation of a generalized
Langevin type for the evolution operator of an atomic ensemble in a microcavity in an external broadband quantized field and
in a nonresonant field of the microcavity. We show that, depending on the number of particles in the atomic ensemble, its
dynamics demonstrates both the Langevin and the generalized Langevin types of the two-photon spontaneous decay. In this case,
one photon is emitted into the cavity mode, whereas the other photon is emitted into the external broadband electromagnetic
field. The Langevin type is determined by a considerable Stark interaction of the atomic ensemble with the broadband photon-free
quantized field. We show that, here, the Stark interaction is represented by a quantized Poisson process and, depending on
its magnitude (at certain numbers of atoms in the ensemble), the two-photon collective spontaneous emission of microcavity
atoms can be completely suppressed. In this case, the two-photon spontaneous emission of the singly excited atomic ensemble
is described by the two-level model, while the atom-photon cluster of the microcavity under the described conditions is an
artificial two-level quantum particle with a strong Stark interaction. 相似文献
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LIANGXian-Ting SUNMing-Zhai 《理论物理通讯》2002,37(4):405-406
Resonance fluorescences of two-photon two-level and two-photon three-level atoms driven by laser are investigated with supersymmetric transformation.It is shown that the spectrum of fluorescent light obtained from the supersymmetric transformation is more accurate and the physical process shown by this method is clearer than that from dress transformation. 相似文献
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In a previous work [Commun. Theor. Phys. 45 (2006) 79] a scheme waspresented for approximate and conditional teleportation of an unknown atomicstate in a QED-cavity without Bell-state measurement via two-photonJaynes-Cummings model in the effective Hamiltonian approach. This commentpresents an alternative method, based on the so called ``full two-photonJaynes-Cummings Hamiltonian approach". Accordingly, it describes the evolution of the two-photon degenerate process for arbitrary average photon number inside the cavity, as the correct way to implement teleportation in this scenario. 相似文献
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Laser actions and photon statistics far a nondegenerate two-photon laser in an effective three-level stomic system with arbitrary detunlng are Investigated both semiclassically and quantum meehmleally, Due to the two-photon effect, the radiation field easily displays a sub-Foissonian statlstieal distribution. The laser actions for a two-photon and a sihgle-photon loss mechanisms are compared. It is found that the detailed balance in the single-photon loss mechanism can still be preserved in the case that a first-order phase transtion takes place. 相似文献
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G. L. Deçordi A. Vidiella-Barranco 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,65(3):587-591
In this paper we investigate some aspects of the dynamics and entanglement of bipartite
quantum system (atom-quantized field), coupled to a third “external” subsystem (quantized
field). We make use of the Raman coupled model; a three-level atom in a lambda
configuration interacting with two modes of the quantized cavity field. We consider the
far off resonance limit, which allows the derivation of an effective Hamiltonian of a
two-level atom coupled to the fields. We also make a comparison with the situation in
which one of the modes is treated classically rather than prepared in a quantum field
(coherent state). 相似文献
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M. Mohammadi M. H. Naderi M. Soltanolkotabi 《International Journal of Theoretical Physics》2008,47(4):983-1004
In this paper, we study the dissipative dynamics of the phase damped Jaynes–Cummings model under the Markovian approximation
in the presence of a classical homogeneous gravitational field. The model consists of a moving two-level atom simultaneously
exposed to the gravitational field and a single-mode traveling radiation field in the presence of a phase damping mechanism.
We first present the master equation for the reduced density operator of the system under the Markovian approximation in terms
of a Hamiltonian describing the atom-field interaction in the presence of a homogeneous gravitational field. Then, by making
use of the super-operator technique, we obtain an exact solution of the master equation. Assuming that initially the radiation
field is prepared in a Glauber coherent state and the two-level atom is in the excited state, we investigate the influence
of gravity on the temporal evolution of collapses and revivals of the atomic population inversion, atomic dipole squeezing,
atomic momentum diffusion, photon counting statistics and quadrature squeezing of the radiation field in the presence of phase
damping. 相似文献