利用偶极封锁制备多粒子三维纠缠态

选择碱金属原子的三个稳定基态为qutrit,其里德堡态为辅助态,借助调节经典脉冲所实现的单量子比特操作和偶极封锁机制分别制备了两原子三维最大纠缠态和三原子三维最大纠缠态。     

Quantum Teleportation of an Unknown Two-Atom Entangled State Using Four-Atom Cluster State

A simply protocol for quantum teleportation of an unknown two-atom entangled state using four-atom cluster state is investigated in cavity quantum electrodynamics (QED). In this protocol, by using a one-dimensional maximally four-atom cluster state as quantum channel, an unknown two-atom entangled state can be transmitted from the sender (Alice) to the receiver without apparent joint Bell-state measurement. According to the results measured by the sender, the receiver can obtain the original state with unit successful probability. The important features of our scheme can also be demonstrated in ion trap system.     

Effect of Cavity Decay on Entanglement of Ladder-Type Three-Level Atoms and a Two-Mode Cavity Field

Considering the adiabatical approximation and the large detuning condition, we give the effective Hamiltonian of a ladder-type three levels atom interacting with a bimodal cavity field. If two identical three-level atoms are sent through the cavity one by one, a two-atom entangled state can be generated. With the choice of the appropriate interaction time, a maximally entangled state of two atoms can be obtained if decoherence effect is ignored. Moreover, we discuss the effect of cavity decay on four physical quantities including atomic population probability, residual entanglement of the first atom and the cavity field, concurrence between the two atoms, and fidelity for generating atomic EPR state, all of which decrease with the increase of cavity decay when the other parameters are fixed.     

High efficient scheme for remote state preparation with cavity QED

In this paper, a scheme is proposed for remote state preparation （RSP） with cavity quantum electrodynamics （QED）. In our scheme, two observers share two-atom nonmaximally entangled state as quantum channels and can realize remote preparation of state of an atom. We also propose a generalization for remote preparation of N-atom entangled state by （N＋1）-atom GHZ-like state （N ≥ 2）. By this scheme, one single-atom projective measurement is enough for the RSP of a qubit or N-atom entangled state, and the probability of success for RSP is unity. Furthermore, we have considered the case where observers use W-like state as quantum channels to realize RSP of a qubit. We compare our scheme with existing ones.     

Generation of Entangled Multi-atom Dicke States in Cavity Quantum Electrodynamics

We propose a scheme to generate two-atom maximally entangled state in cavity quantum electrodynamies （QED）. The scheme can 5e extended to generation of entangled multi-atom Dicke states if we control the interaction time of atoms with cavity modes. We use adiabatically state evolution under large atom-cavity detuning, so the scheme is insensitive to atomic spontaneous decay. The influence of cavity decay on fidelity and success probability is discussed.     

外场驱动下腔QED中实现任意两原子态的隐形传送方案

提出了一种外场驱动下在腔QED中实现任意两原子态隐形传送的方案.在隐形传送的过程中.以两原子最大纠缠态作为量子通道,不用考虑腔场耗散和外界热场环境的影响.在传送过程中包含着对原子的Bell基测量,但不需要直接进行Bell基测量,而且最终能成功实现传送的几率为1.0.同时这种方案也可以用来传送未知的三原子GHZ态,传送的几率也为1.0.     

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.     

Teleportation of a two-atom entangled state using a single EPR pair in cavity QED

We propose a scheme for teleporting a two-atom entangled state in cavity quantum electrodynamics (QED). In the scheme, we choose a single Einstein--Podolsky--Rosen (EPR) pair as the quantum channel which is shared by the sender and the receiver. By using the atom--cavity-field interaction and introducing an additional atom, we can teleport the two-atom entangled state successfully with a probability of 1.0. Moreover, we show that the scheme is insensitive to cavity decay and thermal field.     

Generation of multipartite entangled states by cavity QED

We propose the methods of generating multipartite entanglement by considering the interaction of a system of N two-level atoms in M cavities of high quality factor with a strong classical driving field. It is shown that, with the cavity detuning, the applied driving field detuning and vacuum Rabi coupling, we can produce an entangled coherent state in two single-mode cavities and generate the entangled coherent cluster states in two bimodal vacuum cavities. Tuning these parameters also allows us to acquire the anti-Jaynes-Cummings （AJC） interaction, with which we can generate the maximally two-photon entangled states, and the two-atom and the two-photon entangled cluster states.     

Probabilistic teleportation of an unknown N-atom state using a two-atom nonmaximally entangled state in cavity QED

We present a scheme for realizing probabilistic teleportation of an unknown N-atom state via cavity QED. This scheme requires only a nonmaximally entangled pair to be used as a quantum channel, so the requirement of entanglement is reduced. In addition, our scheme does not involve the Bell-state measurement and is insensitive to the cavity decay, which is important from the experimental point of view. If the quantum channel is a two-atom maximally entangled state, teleportation of an unknown N-atom state can be realized by a simpler scheme via cavity QED.     

A Cavity-QED Scheme for Generating Long-Lived Maximally Entangled States

We propose a potentially practical scheme to generate two-atom maximally entangled states by the large-detuning interaction between two three-level ∧-type atoms and coherent optical fields. Conditioned on the results of detecting cavity field, four pairs of atomic maximally entangled states with unity fidelity and high successful probability can be prepared. We also investigate the influence of the cavity dissipation on the generated entangledstates and discuss the experimental feasibility of our scheme.     

Probabilistic Teleportation of an Arbitrary Two-Atom State in Cavity QED

We propose a scheme for the teleportation of an arbitrary two-atom state by using two pairs of two-atom nonmaximally entangled states as the quantum channel in cavity QED. It is Shown that no matter whether the arbitrary two-atom pure state to be teleported is entangled or not, our teleportation scheme can always be probabilistically realized. The success prohability of teleportation is determined by the smaller coemcients of the two initially entangled atom pairs.     

远程制备双原子纠缠态

提出一种远程制备双原子纠缠态的方案,该方案基于两个原子与单模腔场的同时非共振相互作用.由于双粒子纠缠态比三粒子纠缠态容易制备,方案用两对双原子纠缠态作为量子通道.Alice 拥有的两个相同原子同时与一单模腔场非共振相互作用.Alice已知她要制备的纠缠态,她选择适当的相互作用时间、测量她所拥有的两个原子并通过经典通道通知Bob.Bob引入一个相同的辅助原子和一个单模腔场来实现方案.方案对腔场状态和腔损耗不敏感,基于当前的腔QED 技术,方案能在实验上实现.该方案有望在量子信息过程中有重要的应用价值.     

通过cluster态实现两粒子纠缠态的量子几率隐形传态

提出通过一个四粒子cluster非最大纠缠态作为量子信道来实现一未知两粒子纠缠态的量子几率隐形传态方案。在此方案中,纠缠态可以实现一定的几率传输,此几率由cluster态中绝对值较小的两个系数决定。如果我们用cluster最大纠缠态作为量子信道,此时几率隐形传态就成了一般的隐形传态,即成功传输的几率为100%。     

多光子Tavis-Cummings模型中两纠缠原子的纠缠演化特性

研究了两个纠缠的二能级原子通过多光子跃迁与单模相干光场进行耦合相互作用系统中两原子纠缠的演化特性.计算分析表明,两个原子之间的纠缠呈现出周期性的演化特性,初始两原子的状态、原子间的偶极相互作用、相干光场的参数以及跃迁光子数对两个原子的纠缠有着显著的影响;并发现两原子初始处于某最大纠缠态时,两原子会永远处于该最大纠缠态,因此这一类最大纠缠态可以作为一种量子信息存储器. 关键词： 量子纠缠 部分转置矩阵负本征值 纠缠原子 相干态     

量子隐形传态的类簇态信道方案(英文)

提出了利用一个四粒子类簇态来实现一个任意两粒子态的隐形传送方案.如果接受者能根据发送者提供的测量信息对量子态实施一个合适的幺正变换,那么隐形传送就能以一定的概率实现.由于该方案中充当量子信道的是部分纠缠态,因此该方案比以前基于最大纠缠态的方案更具有现实意义.同时研究导出一个重要的结论:可以从一个四粒子类簇态(部分纠缠态)中以一定的概率提取出一个四粒子簇态(最大纠缠态),这个概率等于成功隐形传态的概率.     

量子隐形传态的类簇态信道方案

提出了利用一个四粒子类簇态来实现一个任意两粒子态的隐形传送方案.如果接受者能根据发送者提供的测量信息对量子态实施一个合适的幺正变换,那么隐形传送就能以一定的概率实现.由于该方案中充当量子信道的是部分纠缠态,因此该方案比以前基于最大纠缠态的方案更具有现实意义.同时研究导出一个重要的结论：可以从一个四粒子类簇态（部分纠缠态）中以一定的概率提取出一个四粒子簇态（最大纠缠态）,这个概率等于成功隐形传态的概率.     

Probabilistic Teleportation of Three-Atom State via Five-Atom Cluster State

A scheme for probabilistic teleportation of an unknown three-atom entangled state via a five-atom non-maximally entangled cluster state as quantum channel is proposed. In this scheme, the sender performs two Bell state and a single-atom measurements on the atoms, the receiver can reconstruct the original state with a certain probability by introducing an auxiliary atom and operating appropriate unitary transformations and controlled-not (C-not) operations according to the sender Alice's measurement results. As a result, the probability of successful teleportation is determined by the smallest two of the coefficients'absolute values of the cluster state. The considerable advantage of our scheme is that we employ a non-maximally entangled cluster state as quantum channel in the scheme, which can greatly reduce the amount of entanglement resources and need less classical bits. If we employ a maximally entangled cluster state as quantum channel, the probabilistic teleportation scheme becomes usual teleportation, the successful probability being 100%.     

通过四个纠缠态粒子来实现未知的三个纠缠态粒子的量子几率隐形传输

提出一种分别利用四个三态粒子的最大纠缠态和非最大纠缠态作为量子通道来传输一未知的三个三态粒子纠缠态的方案.首先考察量子通道是最大纠缠态的情况,然后进一步考察量子通道是非最大纠缠态的情况,同时发现在后者情况时,通过引进一个辅助粒子,并构造一幺正变换矩阵,即可以一定的几率完成该三态粒子纠缠态的隐形传输.     

Efficient scheme for teleportation of an unknown N-atom state via a two-atom entangled state without the Bell-state measurement in cavity QED

We propose a scheme for teleportation of an unknown N-atom state using a two-atom entangled state within a cavity QED and show the feasibility in experiment. Our scheme does not involve the Bell-state measurement and is insensitive to the cavity decay, which is important from the experimental point of view. Another feature of the scheme is that teleporting a N-atom state just requires a small amount of entanglement （i,e. a two-atom entangled state） and less classical bits （two bits）.