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1.
Remote preparation of atomic and field cluster states from a pair of tri-partite GHZ states
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We propose two simple and resource-economical schemes for remote preparation of four-partite atomic as well as cavity field cluster states.In the case of atomic state generation,we utilize simultaneous resonant and dispersive interactions of the two two-level atoms at the preparation station.Atoms involved in these interactions are individually pair-wise entangled into two different tri-partite GHZ states.After interaction,the passage of the atoms through a Ramsey zone and their subsequent detection completes the protocol.However,for field state generation we first copy the quantum information in the cavities to the atoms by resonant interactions and then adapt the same method as in the case of atomic state generation.The method can be generalised to remotely generate any arbitrary graph states in a straightforward manner. 相似文献
2.
We propose the optical generation of W states for three atomic and four atomic qubits, with each qubit trapped in a separate cavity and coupled to the cavity laser. A single-photon source and two classical fields are employed in the present scheme. By encoding the quantum information of each qubit on the degenerate ground states of the atom, we obtain the atomic entanglement that is relatively stable against spontaneous emission. It is demonstrated that the three- and four-atomic W states can be produced deterministically via a proper manipulation of the atom-cavity interaction sequence and time. Generalization of the present scheme to prepare multi-atomic W states is also discussed. 相似文献
3.
M. Bina F. Casagrande A. Lulli 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(2):257-264
We solve the dynamics of an open quantum system where N strongly driven two-level atoms are equally coupled on resonance to a dissipative cavity mode. Analytical results are derived
on decoherence, entanglement, purity, atomic correlations and cavity field mean photon number. We predict decoherencefree
subspaces for the whole system and the N-qubit subsystem, the monitoring of quantum coherence and purity decay by atomic populations measurements, the conditional
generation of atomic multi-partite entangled states and of cavity cat-like states. We show that the dynamics of atoms prepared
in states invariant under permutation of any two components remains restricted within the subspace spanned by the completely
symmetric Dicke states. We discuss examples and applications in the cases N = 3, 4.
An erratum to this article can be found at 相似文献
4.
We propose a scheme for implementing conditional quantum phase gates
for two four-state atoms trapped in a cavity. The two ground states
of the atoms are coupled through two Raman processes induced by the
cavity mode and two classical fields. Under certain conditions
nonresonant Raman processes lead to two-atom coupling and can
be used to produce conditional phase gates. The scheme is
insensitive to cavity decay, thermal photons, and atomic
spontaneous emission. The scheme does not require individual
addressing of the atoms. 相似文献
5.
A cavity quantum electrodynamics (QED) based approach for transferring quantum state between quantum nodes has been proposed, wherein a rubidium (87Rb) atom trapped inside a two-mode optical cavity forms the quantum node and photons serve as the information carrier between two such nodes. Information is encoded into polarized photon states generated through the application of a system of lasers. The focus is made on the phase-space analysis of the approach, wherein two subspaces of the hyperfine energy levels with magnetic sub-levels of rubidium (87Rb) atom represent the logic states ‘0’ and ‘1’. The system of lasers initiates a cavity assisted Raman process which, in turn, generates a right- or left-circularly polarized photon depending on the logic state of the transmit node. Once the photon is received (at the receive node), the logic state of the transmit node is restored into the receive node through a cavity QED process. 相似文献
6.
An experimentally feasible scheme for implementing
four-atom quantum dense coding of an atom--cavity system
is proposed. The cavity is only virtually excited and no quantum information will be
transferred from the atoms to the cavity. Thus the scheme is
insensitive to cavity decay and the thermal field. In the
scheme, Alice can send faithfully 4 bits of classical information to
Bob by sending two qubits. Generalized Bell states can be exactly
distinguished by detecting the atomic state, and quantum dense
coding can be realized in a simple way. 相似文献
7.
Realizing the teleportation of quantum state, especially the teleportation of N-qubit quantum state, is of great importance in quantum information. In this paper, Raman-interaction of the V-type degenerate
three-level atom and single-mode cavity field is studied by utilizing complete quantum theory. Then a new scheme for teleporting
N-qubit unknown atomic state via Raman-interaction of the V-type degenerate three-level atom with a single-mode cavity field
is proposed, which is based upon the complete quantum theory mentioned above. 相似文献
8.
Possible Realization of Cluster States and Quantum Information Transfer in Cavity QED via Raman Transition
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We present a scheme to generate cluster states with many scheme, no transfer of quantum information between the atoms in cavity QED via Raman transition. In this atoms and cavities is required, the cavity fields are only virtually excited and thus the cavity decay is suppressed during the generation of cluster states. The atoms are always populated in the two ground states. Therefore, the scheme is insensitive to the atomic spontaneous emission and cavity decay. We also show how to transfer quantum information from one atom to another. 相似文献
9.
10.
提出基于腔QED技术的多用户间的多原子W态和GHZ态量子信道的建立方案.在量子网络的空闲时段,各个用户和量子交换机共享EPR对.量子交换机通过原子和腔场的相互作用将两个EPR对制备成W态,再与另一个EPR对进行纠缠交换,经过直接测量后为用户建立三原子W态量子信道;同时讨论了四用户间的W态量子信道的建立方案.量子交换机对三个EPR对进行纠缠交换,将三个原子同时与腔场作用,经过直接测量后为用户建立三原子GHZ态量子信道;并将此方法推广到N个用户间的GHZ态量子信道的建立.
关键词:
腔QED
量子信道
量子交换机
纠缠交换 相似文献
11.
We generalize the conception of quantum leakage for the atomic collective excitation states. By making use of the atomic coherence
state approach, we study the influence of the atomic spatial motion on the symmetric collective states of 2-level atomic ensemble
due to inhomogeneous coupling. In the macroscopic limit, we analyze the quantum decoherence of the collective atomic state
by calculating the quantum leakage for a very large ensemble at a finite temperature. Our investigations show that the fidelity
of the atomic system will not be good in the case of atom numberN→∞. Therefore, quantum leakage is an inevitable problem in using the atomic ensemble as a quantum information memory. The
detailed calculations shed theoretical light on quantum processing using atomic ensemble collective qubit. 相似文献
12.
The remote implementation of all possible generalized quantum measurement on single atomic qubit in a quantum network
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To implement generalized quantum measurement (GQM) one has to extend
the original Hilbert space. Generally speaking, the additional
dimensions of the ancilla space increase as the number of the
operators of the GQM n increases. This paper presents a scheme for
deterministically implementing all possible n-operator GQMs on a
single atomic qubit by using only one 2-dimensional ancillary atomic
qubit repeatedly, which remarkably reduces the complexity of the
realistic physical system. Here the qubit is encoded in the internal states
of an atom trapped in an optical cavity and single-photon pulses are
employed to provide the interaction between qubits. It shows that
the scheme can be performed remotely, and thus it is suitable for
implementing GQM in a quantum network. What is more, the number of the
total ancilla dimensions in our scheme achieves the theoretic low
bound. 相似文献
13.
Simple schemes for generation of W-type multipartite entangled states and realization of quantum- information concentration
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We propose simple schemes for generating W-type multipartite entangled states in cavity quantum electrodynamics (CQED). Our schemes involve a largely detuned interaction of Λ-type three-level atoms with a single-mode cavity field and a classical laser, and both the symmetric and asymmetric W states can be created in a single step. Our schemes are insensitive to both the cavity decay and atomic spontaneous emission. With the above system, we also propose a scheme for realizing quantum-information concentration which is the reverse process of quantum cloning. In this scheme, quantum-information originally coming from a single qubit, but now distributed into many qubits, is concentrated back to a single qubit in only one step. 相似文献
14.
给出了依赖强度耦合双模多光子过程Jaynes-Cummings模型的有效哈密顿量.在强场条件下,分别用量子约化熵和量子相对熵研究了上述模型中原子与场之间的纠缠以及双模相干场的模间纠缠演化.研究表明,这两类纠缠演化均与原子跃迁时吸收(或发射)的光子数k密切相关.同时,还揭示了双光子过程(k=1)和多光子过程(k≥2)中不同的纠缠特性.讨论了纠缠态的制备,制备了与时间无关的原子-场的Einstein-Podolsky-Rosen态和双模相干场的模间纠缠态. 相似文献
15.
We present a protocol for multi-party superdense coding
by using multi-atom in cavity quantum electrodynamics (QED).
It is shown that, with a highly detuned
cavity mode and a strong driving field, the protocol is insensitive
to both cavity decay and thermal field. It is even certain to
identify GHZ states via detecting the atomic states. Therefore we can
realize the quantum dense coding in a simple way in the multiparty
system. 相似文献
16.
17.
A protocol to realize complete and nondestructive atomic Greenberger–Horne–Zeilinger (GHZ)‐state analysis in cavity quantum electrodynamics (QED) systems is presented. In this protocol, the three information‐carrier atoms and the three auxiliary atoms are trapped in six separated cavities, respectively. After ten‐step operations, the information for distinguishing the eight different GHZ states of the three information‐carrier atoms is encoded on the auxiliary atoms. Thus, by means of detecting the auxiliary atoms, complete and nondestructive GHZ‐state analysis with high success probability is realized. Moreover, the driving pluses of operations are designed as a simple superposition of Gaussian or trigonometric functions by using the invariant‐based inverse engineering. Therefore, the protocol can be realized experimentally and applied in some quantum information tasks based on complete GHZ‐state analysis with less physical entanglement resource. 相似文献
18.
Scheme for implementing perfect quantum teleportation with four-qubit entangled states in cavity quantum electrodynamics
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Recently, Peng et al. [2010 Eur. Phys. J. D 58 403] proposed to teleport an arbitrary two-qubit state with a family of four-qubit entangled states, which simultaneously include the tensor product of two Bell states, linear cluster state and Dicke-class state. This paper proposes to implement their scheme in cavity quantum electrodynamics and then presents a new family of four-qubit entangled state |Ω4>1234. It simultaneously includes all the well-known four-qubit entangled states which can be used to teleport an arbitrary two-qubit state. The distinct advantage of the scheme is that it only needs a single setup to prepare the whole family of four-qubit entangled states, which will be very convenient for experimental realization. After discussing the experimental condition in detail, we show the scheme may be feasible based on present technology in cavity quantum electrodynamics. 相似文献
19.
研究了含Kerr介质高Q腔内单个二能级原子与双模二项式光场发生双光子共振相互作用系统的腔场谱,给出了Kerr效应与量子干涉项ΔS(ω)关系的数值计算结果,讨论了Kerr效应对二项式腔场谱量子干涉的影响.结果表明:若初始时刻原子处于激发态而双模光场处于二项式态,随Kerr效应的增强,致使量子干涉项引起谱线强度的改变量呈现出"不规则的周期性衰减振荡"特性,震荡幅度与两模光场的频差密切相关.在Kerr系数χg(g为光场与原子的耦合常数)时,Kerr效应对干涉项的影响比较强烈;在χg时,趋于平稳.随着Kerr效应的增强,系统腔场谱由对称结构逐渐演化为不对称的多谱线结构. 相似文献
20.
A sequence of single photons is emitted on demand from a single three-level atom strongly coupled to a high-finesse optical cavity. The photons are generated by an adiabatically driven stimulated Raman transition between two atomic ground states, with the vacuum field of the cavity stimulating one branch of the transition, and laser pulses deterministically driving the other branch. This process is unitary and therefore intrinsically reversible, which is essential for quantum communication and networking, and the photons should be appropriate for all-optical quantum information processing. 相似文献