作者机构：
[Zhang, Deng-Yu; Wang, Xin-Wen; Tang, Shi-Qing; Xie, Li-Jun] Hengyang Normal Univ, Dept Phys & Elect Informat, Hengyang 421008, Peoples R China.;[Yang, Guo-Jian] Beijing Normal Univ, Dept Phys, Beijing 100875, Peoples R China.
通讯机构：
[Wang, Xin-Wen] H;Hengyang Normal Univ, Dept Phys & Elect Informat, Hengyang 421008, Peoples R China.
摘要：
Remote information concentration (RIC) in d-level systems (qudits) is studied. It is shown that the quantum information initially distributed in three spatially separated qudits can be remotely and deterministically concentrated to a single qudit via an entangled channel without performing any global operations. The entangled channel can be different types of genuine multipartite pure entangled states which are inequivalent under local operations and classical communication. The entangled channel can also be a mixed entangled state, even a bound entangled state which has a similar form to the Smolin state, but has different features from the Smolin state. A common feature of all these pure and mixed entangled states is found; i.e., they have d2 common commuting stabilizers. The differences of qudit-RIC and qubit-RIC ( d=2) are also analyzed.
通讯机构：
[Wang, Xin-Wen] H;Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang 421008, Peoples R China.
摘要：
We propose a scheme for multiparty hierarchical quantum-information splitting (QIS) with a multipartite entangled state, where a boss distributes a secret quantum state to two grades of agents asymmetrically. The agents who belong to different grades have different authorities for recovering the boss's secret. Except for the boss's Bell-state measurement, no nonlocal operation is involved. The presented scheme is also shown to be secure against eavesdropping. Such a hierarchical QIS is expected to find useful applications in the field of modern multipartite quantum cryptography.
摘要：
The entanglement dynamics of three-qubit states coupled to a general XY spin-chain with a three-site interaction environment is investigated. By using negativity as entanglement measure, we find that the entanglement evolution depends on not only the system-environment couplings but also the strength of three-site interaction. In the strong-coupling region, the three-site interaction can remarkably enhance the decay of the entanglement of three-qubit states. However, in the weak-coupling region, the process of disentanglement depends on the strength of the three-site interaction.
期刊：
International Journal of Quantum Information,2010年8(8):1301-1314 ISSN：0219-7499
通讯作者：
Wang, Xin-Wen
作者机构：
[Zhang, Deng-Yu; Gao, Feng; Wang, Xin-Wen; Tang, Shi-Qing] Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang 421008, Peoples R China.;[Wang, Xin-Wen] Beijing Normal Univ, Dept Phys, Beijing 100875, Peoples R China.
通讯机构：
[Wang, Xin-Wen] H;Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang 421008, Peoples R China.
关键词：
Quantum secret sharing;GHZ states;security
摘要：
We study the security of multiparty quantum secret sharing (QSS) with multiqubit Greenberger-Horne-Zeilinger states. We give a detailed proof that the original scheme of Xiao et al. [Phys. Rev. A 69 (2004) 052307] is insecure against the interior attack (i.e. the participants' attack) which is the most serious threat for QSS protocols. Thereafter, an improvement of this QSS protocol is proposed.
摘要：
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.
通讯机构：
[Wang, Xin-Wen] H;Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang 421008, Peoples R China.
关键词：
Quantum secret;Hierarchical splitting;Photonic qubit;Cluster states
摘要：
We propose a scheme for hierarchical quantum information splitting with the recently realized six-photon cluster state (Lu et al. in Nat. Phys. 3:91, 2007), where a Boss distributes a quantum secret (quantum state) to five distant agents who are divided into two grades. Two agents are in the upper grade and three agents are in the lower grade. An agent of the upper grade only needs the collaboration of two of the other four agents for getting the secret, while an agent of the lower grade needs the collaboration of all the other four agents. In other words, the agents of two grades have different authorities to recover Boss’s secret. KeywordsQuantum secret-Hierarchical splitting-Photonic qubit-Cluster states
作者机构：
[Tang Shi-Qing; Xie Li-Jun; Zhang Deng-Yu; Gao Feng; Zhan Xiao-Gui] Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Henyang 421008, Peoples R China.;[Tang Shi-Qing; Xie Li-Jun] Xiangtan Univ, Fac Mat & Photoelect Phys, Xiangtan 411005, Peoples R China.
通讯机构：
[Tang Shi-Qing] H;Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Henyang 421008, Peoples R China.
关键词：
No English Keywords
摘要：
We propose a scheme for realization of three-qubit controlled-phase gate via passing two three-level atoms through a high-Q optical cavity in a cavity QED system. In the presented protocol, the two stable ground states of the atoms act as the two controlling qubits and the zero- and one-photon Fock states of the cavity-field form the target qubit, and no auxiliary state or any measurement is required. The numerical simulation shows that the gate fidelities remain at a high level under the influence of the atomic spontaneous emission, the decay of the cavity mode and deviation of the coupling strength. The experimental feasibility of our proposal is also discussed.
