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1.
We demonstrate that the Gaussian entanglement cascading can be realized unconditionally for any nonzero squeezing in all of the entangled sources. We obtain the upper bound of the Gaussian cascaded entanglement, which cannot be exceeded by any entanglement cascading protocol based on Gaussian local operations and classical communications. We then propose an unconditional entanglement cascading protocol that can produce the cascaded entanglement reaching the upper bound. The protocol, as a generalization of the standard continuous variable teleportation, includes two steps: (i) each repeater site locally implements the Bell measurement and classically sends the results to Bob; (ii) Bob optimally displaces his own mode based on these results. 相似文献
2.
Probabilistic Controlled Teleportation of a Triplet W State with Combined Channel of Non-Maximally Entangled Einstein-Podolsky-Rosen and Greenberger-Horne-Zeilinger States
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A scheme for probabilistic controlled teleportation of a triplet W state using combined non-maximally entangled channel of two Einstein-Podolsky-Rosen (EPR) states and one Creenberger-Horne-Zeilinger (CHZ) state is proposed. In this scheme, an (m + 2)-qubit CHZ state serves not only as the control parameter but also as the quantum channel. The m control qubits are shared by m supervisors. With the aid of local operations and individual measurements, including Bell-state measurement, Von Neumann measurement, and mutual classical communication etc., Bob can faithfully reconstruct the original state by performing relevant unitary transformations. The total probability of successful teleportation is only dependent on channel coefficients of EPR states and GHZ, independent of the number of supervisor m. This protocol can also be extended to probabilistic controlled teleportation of an arbitrary N-qubit state using combined non-maximally entangled channel of N- 1 EPR states and one (m + 2)-qubit GHZ. 相似文献
3.
We push the limits of the direct use of partially pure entangled states to perform quantum teleportation by presenting several protocols in many different scenarios that achieve the optimal efficiency possible. We review and put in a single formalism the three major strategies known to date that allow one to use partially entangled states for direct quantum teleportation (no distillation strategies permitted) and compare their efficiencies in real world implementations. We show how one can improve the efficiency of many direct teleportation protocols by combining these techniques. We then develop new teleportation protocols employing multipartite partially entangled states. The three techniques are also used here in order to achieve the highest efficiency possible. Finally, we prove the upper bound for the optimal success rate for protocols based on partially entangled Bell states and show that some of the protocols here developed achieve such a bound. 相似文献
4.
Teleportation of Entangled States through Divorce of Entangled Pair Mediated by a Weak Coherent Field in a High-Q Cavity
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We propose a scheme to partially teleport an unknown entangled atomic state. A high-Q cavity, supporting one mode of a weak coherent state, is needed to accomplish this process. By partial teleportation we mean that teleportation will occur by changing one of the partners of the entangled state to be teleported. The entangled state to be teleported is composed by one pair of particles, we called this surprising characteristic of maintaining the entanglement, even when one of the particle of the entangled pair being teleported is changed, of divorce of entangled states. 相似文献
5.
Hui Zhao 《Physics letters. A》2009,373(43):3924-3930
A sufficient and necessary condition for separability of Bell diagonal mixed states for bipartite systems in higher dimensions is presented. Moreover, we present a necessary condition for genuine entanglement of Bell diagonal mixed states in higher dimensions for multipartite systems. 相似文献
6.
J. Dong J. F. Teng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(1):129-134
In this paper, we explicitly present a general scheme for controlled quantum teleportation of an arbitrary multi-qudit state
with unit fidelity and non-unit successful probability using d-dimensional nonmaximally entangled GHZ states as the quantum channel and generalized d-dimensional Bell states as the measurement basis. The expression of successful probability for controlled teleportation is
present depending on the degree of entanglement matching between the quantum channel and the generalized Bell states. And
the formulae for the selection of operations performed by the receiver are given according to the results measured by the
sender and the controller.
相似文献
7.
We investigate the connection between sub-Planck structure in the Wigner function and the output fidelity of continuous-variable teleportation protocols. When the teleporting parties share a two-mode squeezed state as an entangled resource, high fidelity in the output state requires a squeezing large enough that the smallest sub-Planck structures in an input pure state are teleported faithfully. We formulate this relationship, which leads to an explicit relation between the fine-scale structure in the Wigner function and large-scale extent of the Wigner function, and we treat specific examples, including coherent, number, and random states and states produced by chaotic dynamics. We generalize the pure-state results to teleportation of mixed states. 相似文献
8.
Using the two-mode two-photon Jaynes-Cummings model, entanglement transfer between atoms and field is studied. It is found that when the field is in state constructed from the two-mode photon number states |00〉,|11〉 or the two-mode squeezed vacuum states, full entanglement exchange can be attained no matter the atoms are initially in pure or mixed states. These investigations show that CV entangled states can act as perfectly as the entangled number states in entangling initially separable atoms. The two-mode two-photon atom-field interaction also provides a simple way for the quantum teleportation of atomic or field states. 相似文献
9.
We analyse a process of remote information concentration achieved by the W state. The result turns out to be neither as good as performed by the GHZ state nor as by the Smolin bound entangled state. Based on this particular phenomenon, the properties of the three entangled states are realized. 相似文献
10.
Enlightened by the work of Yeo and Chua [Phys. Rev. Lett. 96 (2006) 060502] for teleportation and dense coding with genuine multipartite entanglement, we present an explicit protocol for faithful remote state preparation in a real coefficient case by using the same four-particle entangled state which is not reducible to pair of Bell states. It is shown that any complex coefficient case can be changed to a real coefficient case. With this protocol, the state can play an analogous role to Einstein-Podolsky-Rosen pairs in the theory of multipartite entanglement. 相似文献
11.
We present an explicit protocol for probabilistic teleport an arbitrary and unknown two-qubit entangled state via a one-dimensional
four-particle non-maximally entangled cluster state. By construction, our four-partite state is not reducible to a pair of
Bell states. We show that teleportation can be successfully realized with a certain probability. This protocol indicate that
the four-qubit state is a likely candidate for the genuine four-particle analogue to a Bell state. 相似文献
12.
A class of unlockable bound entangled states and their applications are presented. They can be considered as quasi generalized Smolin states [Phys. Rev. A 63 (2001) 032306], which are the states of N + N qubits. No pure entanglement can be distilled from this class of states by local quantum operations and classical communications. However, if certain parties group together, they become distillable. Although they are bound entangled states, they could be used to achieve some non-trivial tasks, such as quantum secret sharing shown in the study. 相似文献
13.
We present a controlled teleportation scheme for teleporting an arbitrary superposition state of an M-qudit quantum system. The scheme employs only one entangled state as quantum channel, which consists of the qudits from Alice, Bob and every agent. The quantum operations used in the teleportation process are a series of qudit Bell measurements, single-qudit projective measurements, qudit H-gates, qudit-Pauli gates and qudit phase gates. It is shown that the original state can be restored by the receiver only on the condition that all the agents collaborate. If any agent does not cooperate, the original state can not be fully recovered. 相似文献
14.
We give a protocol to prepare special partially entangled multi-atom W states. Besides, a scheme for deterministic and multi-controlled teleportation of an arbitrary unknown two-level two-atom state via partially entangled W states is proposed. 相似文献
15.
FAN Hong-Yi LIANG Xian-Ting 《理论物理通讯》2005,44(5):833-836
A quantum teleportation scheme to teleport a kind of tripartite entangled states of continuous variables by using a quantum channel composed of three bipartite entangled states is proposed. The joint Bell measurement is feasible because the bipartite entangled states are complete and the squeezed state has a natural representation in the entangled state basis. The calculation is greatly simplified by using the Schmidt decomposition of the entangled states. 相似文献
16.
FAN Hong-Yi LIANG Xian-Ting 《理论物理通讯》2005,44(11)
A quantum teleportation scheme to teleport a kind of tripartite entangled states of continuous variables by using a quantum channel composed of three bipartite entangled states is proposed. The joint Bell measurement is feasible because the bipartite entangled states are complete and the squeezed state has a natural representation in the entangled state basis. The calculation is greatly simplified by using the Schmidt decomposition of the entangled states. 相似文献
17.
We propose a quantum teleportation scheme for tripartite entangled coherent state (ECS) with continuous variable. Our scheme is feasible and economical in the sense that we need only linear optical devices such as beam splitters, phase shifters and photon detectors and employ three bipartite maximally ECSs as quantum channels. We also generalize the tripartite scheme into multipartite ease and calculate the minimum average fidelity for the schemes in tripartite and multipartite cases. 相似文献
18.
We show that, for a continuous set of entangled four-partite states, the task of maximizing the payoff in the symmetric-strategy four-player quantum Minority game is equivalent to maximizing the violation of a four-particle Bell inequality. We conclude the existence of direct correspondences between (i) the payoff rule and Bell inequalities, and (ii) the strategy and the choice of measured observables in evaluating these Bell inequalities. We also show that such a correspondence is unique to minority-like games. 相似文献
19.
We describe a protocol for quantum state teleportation via mixed entangled pairs. With the help of an ancilla, near-perfect teleportation might be achieved. For pure entangled pairs, perfect teleportation might be achieved with a certain probability without using an ancilla. The protocol is generalized to teleportation of multiparticle states and quantum secret sharing. 相似文献
20.
G. Gordon G. Rigolin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(2):347-353
We present a generalized telecloning (GTC) protocol
where the quantum channel is non-optimally entangled and we study
how the fidelity of the telecloned states depends on the
entanglement of the channel. We show that one can increase the
fidelity of the telecloned states, achieving the optimal value in
some situations, by properly choosing the measurement basis at
Alice's, albeit turning the protocol to a probabilistic one. We
also show how one can convert the GTC protocol to the
teleportation protocol via proper unitary operations. 相似文献