Solutions of two-mode Jaynes-Cummings models

A simple procedure to solve two fully quantized non-linear Jaynes-Cummings models is presented, one in which an atom interacts with a two-mode radiation field in a Raman-type process and the other involving multiphoton interaction between the two-mode field and the atom. Effect of intensity-dependent coupling between the field and the atom in both the above-mentioned cases has also been investigated. The unitary transformation method presented here not only solves the time-dependent problem but also permits a determination of the eigensolutions of the interacting Hamiltonian at the same time. Graphical features of the time dependence of the population inversion have been analysed when one of the field modes is prepared initially in a coherent state while the other one in a vacuum state.      

Exact Solutions for Jaynes-Cummings Models with Non-degenerate Two-Photon Transitions in the Ladder Configuration

In the present paper, the eigenfunctions and eigenvalues of the Hamiltonian of the interacting system have been obtained in two generalized Jaynes Cummings models separately, one in which the transition are mediated by two different modes of photon in the ladder configuration and the other involving two mode multi-photon interaction between the field and the atom. Effect of intensity dependent coupling between the field and the atom in both the above-mentioned cases have been investigated. Graphical features of the time dependence of population inversion have been analyzed when one of the field modes is prepared initially in a coherent state while the other one in a vacuum state.     

A theoretical scheme for generation of Gazeau-Klauder coherent states via intensity-dependent degenerate Raman interaction

A theoretical scheme is presented for generating Gazeau-Klauder coherent states (GKCSs) via the generalization of degenerate Raman interaction with coupling constant to intensity dependent coupling. Firstly, we prove that in the intensity dependent degenerate Raman interaction, under particular conditions, the modified effective Hamiltonian can be used instead of Hamiltonian in the interaction picture, for describing the atom-field interaction. We suppose that the cavity field is initially prepared in a nonlinear CS, which is not temporally stable. As we will observe, after the occurrence of the interaction between atom and field, the generated state involves a superposition of GKCSs which are temporally stable and initial nonlinear CS. Under specific conditions which may be prepared, the generated state just includes GKCS. So, in this way we produced the GKCS, successfully.     

利用原子与SU(2)相干态腔场的Raman相互作用制备原子纠缠态

利用一个参量频率转换过程,在腔中制备双模SU(2)相干态,然后注入一系列全同的Λ型三能级原子,这些原子与腔场的一个模发生拉曼相互作用,通过系列原子-腔场相互作用生成腔场-原子纠缠态,通过对腔场进行选择性测量,可获得多种形式多原子纠缠态.     

Simplified Scheme for Testing Symmetrization Postulate for Photons

We propose a scheme for testing the small violations of the symmetrization postulate （SP） for photons in cavity QED. In the scheme, a degenerate A-type three-level atom is sent through a cavity field initially in a q-deformed coherent state. After an appropriate interaction time, the atom is measured by a state-selective detector. The probability that the atom makes a transition from one of the lower states to the other characterizes the violation of the SP. In the scheme, only one atom is required and classical fields are unnecessary, which is prior to the previous schemes.     

利用原子-腔场的拉曼相互作用制备双模SU(2)薛定谔猫态

利用一个参量频率转换过程,在腔中制备双模ＳＵ（２）相干态,然后注入一个与腔场的一个个模发生拉曼相互作用的Ａ型三能级原子,通过原子－腔场相互作用生成腔场－原子纠缠,通过对原子进行选择性测量,腔场－原子纠缠态将塌缩到纯态,即双模ＳＵ（２）薛定谔猫态。     

Generation of W-Type Entangled Coherent States of Three-Cavity Fields by a Driving Classical Field

A scheme is proposed to generate the W-type entangled coherent states of three-cavity field. The scheme is based on the resonant atom-field interaction, thus the interaction time between the atom and the cavity is greatly reduced, which is important in view of decoherence. Furthermore, the scheme does not need accurate adjustment of the interaction time.     

Preparation of Entangled Atomic States Through Resonant Atom-Field Interaction

A scheme is proposed for the generation of two-atom maximally entangled states and multi-atom maximally entangled states of W class. The scheme is based on the simultaneous resonant interaction of atoms with a single-mode cavity field. It does not require accurate adjustment of the interaction time. The time needed to complete the generation does not increase with the number of the atom.     

Resonant decay of a two state atom interacting with a massless non-relativistic quantised scalar field

We consider a model Hamiltonian derived from the interaction of an atom with a non-relativistic massless quantized field. The model atom has two states, and the interaction is linear in the field operator. We do not make the rotating wave approximation and there is no infrared cutoff. We prove that the excited state of the atom with no photons present decays at an approximately exponential rate in accordance with the predictions of time dependent perturbation theory. The proof requires some analyticity and regularity assumptions on the interaction between atom and field. These imply in particular that the interaction goes to zero at least as fast ask ², ask0, wherek is the photon momentum.     

Preparation of Two atoms Entangled States via the Quantized Cavity Field Resonant Interaction with AtomSupported by the Young Core Teacher and Domestic Visitor Foundation of the Education Committee of Hunan Province.

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Quantum entanglement in the mode-mode competition system

Considering a two-level atom interacting with the competing two-mode field, this paper investigates the entanglement between the two-level atom and the two-mode field by using the quantum reduced entropy, and that between the two-mode field by using the quantum relative entropy of entanglement. It shows that the two kinds of entanglement are dependent on the relative coupling strength of atom-field and the atomic distribution, and exhibit the periodical evolution. The maximal atom-field entanglement state can be prepared via the appropriate selection of system parameters and interaction time.     

利用原子-腔场共振相互作用制备多原子缠结态

提出了一个利用量子腔场与原子的共振相互作用制备多原子缠结态的方案.首先将一个初态制备在基态和激发态的叠加态的二能级原子注入一个真空态腔场中.原子通过腔时产生原子-场缠结.制备于基态的其它二能级原子分别以不同角度注入腔场,在与腔场相互作用时可制得多原子缠结态,而空腔仍然保持在真空态.与现存的方案比较,该方案在实验上更容易实现.     

Interaction of the Light Field with N Atoms Possessing Dipole-dipole Interaction

The interaction of the light field with two-level atoms possessing dipole-dipole interaction is studied. It is shown that a light field at coherent state can produce a squeezed atom laser.     

利用三原子W类纠缠态在腔量子电动力学体系中实现单原子态的远程制备

提出了两个利用三原子W类纠缠态作为量子通道.在腔量子电动力学(QED)体系中实现单原子态的远程制备方案:一个是接收者借助于原子与单模腔场之间的大失谐相互作用实现初始态重建,另一个则是接受者利用原子与单模腔场之间的共振相互作用完成远程态制备.两方案中都涉及到了一位发送者和两位接收者,发送者可以将被传送态远程制备到两位接收者中的任何一位的手中,而另一位接受者必须为其提供必要的协助.表明利用原子与腔场之间的大失谐相互作用的方法可以很好地克服腔场的消相干,降低对腔品质因子的要求;而利用共振相互作用的方法则无需引入辅助原子,操作简便.但不论采用何种方法,实现单原子远程态制备的总成功概率是相同的.     

Preparation of Two-atoms Entangled States via the Quantized Cavity Field Resonant Interaction with Atom

A scheme for preparation of the two-atoms entangled state via the resonant interaction of a quantized cavity field with atom is presented. It is injected an two-level atom initially prepared in the superposition of the ground state and excited state through the cavity prepared in the vacuum state. The atom passing through the cavity creates atom-field entanglement. The second two-level atom prepared in the ground state is injected into the cavity at different angle. After the interaction with the cavity field, the two-atoms entangled state is produced and the cavity field is still in the vacuun state. Comparing with the existing schemes, ours is easier to realize experimently.     

Generation of entangled coherent states for two cavity modes via resonant interaction with a V-type three-level atom

This paper proposes a scheme for the generation of entangled coherent states for two cavity modes. In the scheme a V-type three-level atom is sent through a two-mode cavity filled with a coherent field. After the atom cavity interaction and detection of the atomic state the cavity modes may evolve to a superposition of two-mode coherent states. As the scheme is based on resonant atom-cavity interaction, the required interaction time is short, which is important in view of the decoherence. Moreover, additional classical pulses are unnecessary before and after the atom-cavlty interaction.     

Interaction of the Light Field with N Atoms Possessing Dipole-dipole Interaction

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Generation of four-photon W state via cavity QED

This paper proposes an alternative scheme for generating four-photon W state via cavity QED. The scheme bases on the resonant interaction of a A-type three level atom with two bimodal cavities. The detection of atom collapses the cavity to the desired state. Comparing with previous schemes, the advantage of this scheme is that the interaction time can be greatly shortened since it uses the resonant interaction between atom and cavities. Moreover, the proposed scheme is more experimentally feasible than the previous ones.     

The dynamic properties of the two-level entangled atom in an optical field

The interaction of an optical field and one of the entangled atoms is analyzed in detail in this paper. Furthermore, the dynamic properties of the two-level entangled atom are manifested. The properties of the action are dependent on the initial state of the atom. After detecting the atom out of the field, we can obtain the state of the other atom moving in the field. It is shown that the state of the atom out of the field influences the dynamic properties of the atom in the field.     

Squeezing of an atom laser originating from atomic Bose-Einstein condensate interacting with light field

The quadrature squeezing properties of an atom laser originating from atomic Bose-Einstein condensate interacting with light field are studied. We find that the squeezing properties of the atom laser are dependent on the initial light field interacting with the atomic Bose-Einstein condensate. If the initial light field cannot be squeezed, such as number state or coherent state light field, the atom laser as well cannot be squeezed. However, if the initial light field interacting with the atomic Bose-Einstein condensate being in squeezed state, the atom laser can be squeezed periodically, and its squeezing depth is dependent on the intensity of interatoms interaction.