The Level-split of the Two-level Entangled Atom in an Optical Field

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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.     

三能级原子与奇偶纠缠相干光作用的光场压缩

采用求解薛定谔方程和数值计算方法,研究了V型三能级原子与双模奇偶纠缠相干光场相互作用过程中的光场压缩效应,讨论了压缩效应与双模奇偶纠缠相干光场的纠缠程度、系统失谐量、双模光场的平均光子数和原子基态概率幅的依赖关系。结果表明：光场压缩效应与双模奇偶纠缠相干光场的纠缠程度、失谐量、平均光子数和原子初态相关联：双模纠缠相干光场处于非纠缠状态时的光场压缩量比光场处于纠缠状态时要大;原子处在单纯的基态或激发态时光场都有明显的压缩现象出现;而原子初态中基态和激发态的概率幅较接近时无光场压缩现象;无论光场是否处于纠缠态,只有两模平均光子数接近时,光场才会出现压缩效应。     

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.     

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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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.     

两纠缠原子与二项式光场相互作用的动力学

采用时间演化算符和数值计算方法，研究了两全同二能级纠缠原子与二项式光场相互作用的动力学，结果表明原子布居和原子偶极压缩的时间演化与二项式光场系数和两纠缠原子的纠缠度有很强的关联，选择合适的系统参数，原子偶极矩可以被完全压缩. 关键词： 纠缠原子 二项式态 原子布居 偶极压缩     

Preparation of steady-state entanglement via a laser-excited resonant interaction

In this paper we propose a scheme in which two-mode entanglement in a steady state is produced by using two lasers to resonantly drive a single four-level atom embedded inside a two-mode optical cavity.In this scheme,atomic coherence induced by a classical laser plays an important role in the process of preparing the entangled state.With the coupling of a strong control field,direct two-photon transition is generated and the relatively weak pump field induces the parametric interaction between two photons,which makes them entangle with each other.By numerical calculation,we find that the degree of entanglement depends strongly on the Rabi frequencies of the classical laser fields and the cavity losses.     

Preparation of Multi2cavity Entangled States

A scheme is proposed for the generation of maximally entangled field states in multiple cavities. In the scheme an appropriately prepared ladder-type multi-level atom is sent through the cavities initially in vacuum states. After resonant interactions the cavity system is prepared in a highly entangled state with the atom left in its lowest state.     

Preparation of Multi-cavity Entangled States

Ｅｎｔａｎｇｌｅｍｅｎｔｉｓｏｎｅｏｆｔｈｅｓｔｒｉｋｉｎｇｆｅａｔｕｒｅｓｏｆｑｕａｎｔｕｍｍｅｃｈａｎｉｃｓ．Ｉｆｔｗｏｉｎｄｉｖｉｄｕａｌｓｙｓｔｅｍｓａｒｅｉｎａｎｅｎｔａｎｇｌｅｄｓｔａｔｅｔｈｅｙｃａｎｎｏｔｂｅｃｏｎｓｉｄｅｒｅｄｉｎｄ...     

原子自发辐射中偶极矩的涨落与最大纠缠态的保持

研究了二能级原子与电磁场相互作用体系的自发辐射与量子纠缠态.在原子的自发辐射过程中,其偶极矩的期待值总是零,但偶极矩的涨落恒等于一个不为零的常量,因此原子的自发辐射是由真空起伏导致偶极矩的涨落引起的.Jaynes-Cummings模型是产生量子纠缠态的重要体系,研究发现,原子与场纠缠态的信息熵和纠缠度随时间作周期性的振荡,量子态在非纠缠与纠缠态之间变化.更为重要的是,在失谐量适当时,量子态将长时间停留在最大纠缠态.     

Relaxation in an entangled thermostat

A generalized Lindblad equation is derived that describes the relaxation of two systems of an arbitrary physical nature in an entangled thermostat. The relaxation of an atom and a mode of the electromagnetic field selected by a high-Q cavity is considered as an example. Using the introduced collective operators for an atom and a mode, it is shown that the entangled state of the thermostat can lead to the coherent and squeezed state of the atom and the mode.     

A Scheme for Generating Entangled Squeezed States Based on Cavity QED

We propose a scheme for generating entangled squeezed vacuum states of electromagnetical fields. The scheme is based on cavity QED. In this scheme, an atom interacts, successively, with a classical field, two quantum cavity fields, and another classical field. By detecting the final states of the atom, the two quantum cavity fields will be projected to an entangled state.     

Entanglement dynamics and decoherence of an atom coupled to a dissipative cavity field

In this paper, we investigate the entanglement dynamics anddecoherence in the interacting system of a strongly driventwo-level atom and a single mode vacuum field in the presence ofdissipation for the cavity field. Starting with an initial productstate with the atom in a general pure state and the field in avacuum state, we show that the final density matrix is supportedon \({\mathbb C}^2\otimes{\mathbb C}^2\) space, and therefore, theconcurrence can be used as a measure of entanglement between theatom and the field. The influences of the cavity decay on thequantum entanglement of the system are also discussed. We alsoexamine the Bell-CHSH violation between the atom and the field andshow that there are entangled states for which the Bell-BCSHinequality is not violated. Using the above system as a quantumchannel, we also investigate the quantum teleportation of ageneric qubit state and also a two-qubit entangled state, and showthat in both cases the atom-field entangled state can be useful toteleport an unknown state with fidelity better than any classicalchannel.     

A Scheme for Teleportation of an Unknown Entangled Coherent State via Raman Interaction

A scheme is reported for the teleportation of entangled coherent states through the degenerate Raman interaction.The scheme uses an entangled state of an atom and two coherent states as a quantum channel.It makes full use of coherent cavity fields.Furthermore,it does not need any classical field to transform the atom states.     

Scheme for Concentration of Unknown Greeberger-Horne-Zeilinger Entangled States via Cavity Decay

We present a scheme for entanglement concentration of an unknown atomic non-maximally entangled GHZ state via cavity decay. In the scheme, the atom trapped in a cavity is manipulated by laser field, so the maximally entangled GHZ state can be obtained by performing certain operation, which can be realized by illuminating the atom in a cavity. Our method is robust against spontaneous atomic decay.     

Concentration of Non-maximally Entangled States via Entanglement Swapping in Cavity QED

Using the highly detuned interaction between Λ-type three-level atoms and coherent optical fields in cavity QED, we can create a maximally entangled state between an atom and a cavity mode from a non-maximally entangled atomic state and a non-maximally entangled coherent state via entanglement swapping. The averaged output entanglement of the scheme is the product of the initial two non-maximal entanglements rather than the sum of them. The impact made by the spontaneous emission from the atomic excited levels has been canceled here, which makes the current protocol more feasible.     

Entanglement swapping between atom and cavity and generation of entangled state of cavity fields

This paper proposes a scheme where entanglement swapping between atom and cavity can be realized. \Lambda -type three-level atoms interacting resonantly with cavity field are considered. By detecting atom and cavity field, it realizes entanglement swapping between atom and cavity. It uses the technique of entanglement swapping to generate an entangled state of two cavity fields by measuring on atoms. It discusses the experimental feasibility of the proposed scheme and application of entangled state of cavity fields.     

利用V-型三能级原子与双模腔场双光子大失谐相互作用制备W纠缠态

本文提出利用V-型三能级原子与双模腔场的双光子大失谐相互作用制备W纠缠态,该方案要求三个三能级原子和一个双模腔场,第一个与腔场作用的原子最初处于激发态,第二个和第三个原子均处于基态,腔场最初处于真空态,合适地选择原子与腔场之间的相互作用时间即可获得三原子W纠缠态.并且此方案可以推广至多原子W纠缠态和多腔场W纠缠态的制备;通过计算共生纠缠度研究系统中态的纠缠演化以及热纠缠现象.     

利用V-型三能级原子与双模腔场 双光子大失谐相互作用制备W纠缠态

本文提出利用 型三能级原子与双模腔场的双光子大失谐相互作用制备W纠缠态,该方案要求三个三能级原子和一个双模腔场,第一个与腔场作用的原子最初处于激发态,第二个和第三个原子均处于基态,腔场最初处于真空态,合适地选择原子与腔场之间的相互作用时间即可获得三原子W纠缠态。并且此方案可以推广至多原子W纠缠态和多腔场W纠缠态的制备;通过计算共生纠缠度研究系统中态的纠缠演化以及热纠缠现象。