共查询到20条相似文献,搜索用时 10 毫秒
1.
Generation of Greenberger-Horne-Zeilinger states for multiple atoms trapped in separated cavities 总被引:1,自引:0,他引:1
S. B. Zheng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(3):719-722
We propose a scheme for generating maximally entangled states for multiple atoms trapped in distant cavities connected by
fibers. During the operation neither the atomic system nor the fibers are excited, which is important in view of decoherence.
Under certain conditions, the probability that the cavities are excited is negligible. The scheme does not include projective
measurement and the GHZ state is generated deterministically. Taking advantage of adiabatic passage, the entanglement fidelity
is insensitive to fluctuation of experimental parameters. 相似文献
2.
J. S. Zhang J. B. Xu Q. Lin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,51(2):283-288
We investigate the entanglement dynamics of a quantum system consisting of two-level atoms interacting with vacuum or thermal
fields with classical driving fields. We find that the entanglement of the system can be improved by adjusting the classical
driving field. The influence of the classical field and the purity of the initial state on the entanglement sudden death is
also studied. It is shown that the time of entanglement sudden death can be controlled by the classical driving fields. Particularly,
the entanglement sudden death phenomenon will disappear if the classical driving fields are strong enough. 相似文献
3.
Xi-Wen Hou Jing-Hua Chen Ming-Fang Wan Zhong-Qi Ma 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(1):37-41
The dynamical comparison of entanglement, measured by linear entropy and negativity, is carried out for initial pure separable
states in vibrations of H2O and SO2. It is shown that both measures of an initial state with local-mode character have the same period for H2O, while those of an initial state with normal-mode character are no longer identical in period. When the total quantum number
of the initial state is one, both measures rise and lower together with the period for H2O being larger than that for SO2. For a suitable state in H2O, both measures exhibit a beat phenomenon with a long period. 相似文献
4.
Y. Z. Wu C. H. Shi X. Hao T. Pan X. F. Jiang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(2):253-257
The evolution of entanglement in a one-dimensional Ising chain with both two-body and three-body interactions, under two types
of initial states, is numerically simulated. We analyse three problems concerning the dynamics of pairwise entanglement: (i)
the possibility of generating large entanglement from an initial separable state by the use of a selective irradiation scheme;
(ii) the effect of three-body interaction on the generation of entanglement from an initial separable state; (iii) the effect
of three-body interaction on the decay of the entanglement from a state with only (m,n)-pair maximal entangled, and the rest
in product form. It is shown that a large pairwise concurrence Cmn can be obtained when the resonant, transverse radio-frequency fields are selectively switched on from the mth to nth spins.
Three-body interaction will decrease the oscillation amplitude of the nearest neighbour concurrence, while the oscillation
amplitude of remote pairwise concurrence will be greatly increased with the consideration of three-body interactions. For
an initial (m,n)-pair maximal entangled state, a slow decay of the pairwise concurrence Cmn is found with the introduction of three-body interactions. 相似文献
5.
C.-S. Yu X. X. Yi H.-S. Song D. Mei 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(3):411-415
We have proposed a simple scheme to entangle two distant
qutrits trapped in separate optical cavities. The quantum
information of each qutrit is skillfully encoded on the degenerate
ground states of a pair of atoms, hence the entanglement between
them is relatively stable against spontaneous emission. In
Lamb-Dicke limits, it is not necessary to require coincidence
detections, which will relax the conditions for the experimental
realization. The scheme is robust against the inefficient
detections. 相似文献
6.
C. Sabín G. García-Alcaine 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(3):435-442
We present a classification of three-qubit states based in their three-qubit and reduced two-qubit entanglements. For
pure states these criteria can be easily implemented, and the different types can be related with sets of equivalence classes
under local unitary operations. For mixed states characterization of full tripartite entanglement is not yet solved in general;
some partial results will be presented here. 相似文献
7.
Z. X. Man Y. J. Xia N. B. An 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(2):229-236
A double Tavis-Cummings model (DTCM) is developed to simulate the entanglement dynamics of realistic quantum information processing where two entangled atom-pairs AB and CD are distributed in such a way that atoms AC are embedded in a cavity a while BD are located in another remote cavity b. The evolutions of different types of initially shared entanglement of atoms are studied under various initial states of cavity fields. The results obtained in the DTCM are compared with that obtained in the double Jaynes-Cummings model (DJCM) [M. Yönaç, T. Yu, J.H. Eberly, J. Phys. B 40, S45 (2007)] and an interaction strength theory is proposed to explain the parameter domain in which the so-called entanglement sudden death occurs for both the DTCM and DJCM. 相似文献
8.
Shi-Biao Zheng 《Physics letters. A》2008,372(5):591-595
A scheme is proposed for generating maximally entangled states for three atoms trapped in a two-mode cavity. The scheme is based on resonant atom-cavity interaction and linear optics elements. The fidelity of the entangled state is not affected by both the decoherence and detection inefficiencies. The scheme works beyond the strong-coupling regime, which is important for high-fidelity entanglement engineering under realistic conditions. 相似文献
9.
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
10.
P. Milman A. Keller E. Charron O. Atabek 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(3):383-392
We make a detailed study of Bell-type inequalities based on correlations between measurements of continuous observables performed
on trapped molecular systems. We show that, in general, when an observable has a continuous spectrum which is bounded, one
is able to construct non-locality tests sharing common properties with those for two-level systems. The specific observable
studied here is molecular spatial orientation, and it can be experimentally measured for single molecules, as required in
our protocol. We also provide some useful general properties of the derived inequalities and study their robustness to noise.
Finally, we detail possible experimental scenarios and analyse the role played by different experimental parameters. 相似文献
11.
J.?Pe?ina J.?K?epelka J.?Pe?inaJr M.?Bondani A.?Allevi A.?Andreoni 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(3):373-382
Two strongly-pumped parametric interactions are
simultaneously realized in a single nonlinear crystal in order to
generate three strongly correlated optical fields. By combining
together the outputs of two of the three detectors measuring
intensities of the generated fields, we obtain the joint
photocount statistics between the single field and the sum of the
other two. We apply a microscopic quantum theory developed earlier
to determine the joint photon-number distribution and the joint
quasi-distributions of integrated intensities and prove
nonclassical nature of the three-mode state. Finally, by
performing a conditional measurement on the single field, we
obtain a state endowed with a sub-Poissonian statistics, as
testified by the analysis of the conditional Fano factor. The role
of quantum detection efficiencies in this conditional
state-preparation method is discussed in detail. 相似文献
12.
M. A. Jafarizadeh M. Mahdian A. Heshmati K. Aghayar 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,50(1):107-121
The three qubits mutually unbiased bases (MUB) diagonal density matrices with maximally entanglement in Greenberger-Horne-Zeilinger
(GHZ) basis are studied. These are a natural generalization of Bell-state diagonal density matrices. The linearity of positive
partial transpose (PPT) conditions allows one to specify completely PPT states or feasible region (FR) which form a polygon,
where the projection of the feasible region to some two dimensional planes has lead to better visualization. To reveal the
PPT entangled regions of these density matrices, we manipulate some appropriate optimal non-decomposable linear entanglement
witnesses (EWs) as the envelope of family of linear optimal non-decomposable EWs. These nonlinear EWs are nonlinear functional
of MUB diagonal states, so that they are nonnegative valued over all separable, but they are negative valued over some PPT
entangled MUB diagonal states. Even though, these nonlinear EWs can not separate completely, the PPT entanglement region from
separable one, but however in special cases they lead to necessary and sufficient condition for separability. To support the
evidence, we study three categories for special choices of parameters in density matrices, and using the nonlinear EWs we
can distinguish the region of PPT entangled states and separable states, completely. At the end some numerical simulations
are provided to show the practical applicability of these nonlinear EWs in detecting some PPT entangled MUB diagonal states. 相似文献
13.
P. D?m?t?r M. G. Benedict 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(2):237-242
We consider a quantum system consisting of N parts, each of which is a “quKit” described by a K dimensional Hilbert space.
We prove that in the symmetric subspace, , a pure state is not globally entangled, if and only if it is a coherent state. It is also shown that in the orthogonal complement
all states are globally entangled. 相似文献
14.
Quantum controlled phase gate and cluster states
generation via two superconducting quantum interference devices in a
cavity 总被引:3,自引:0,他引:3
Z.-Y. Xue G. Zhang P. Dong Y.-M. Yi Z.-L. Cao 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(3):333-336
A scheme for implementing 2-qubit quantum controlled phase gate (QCPG) is proposed with two superconducting quantum interference
devices (SQUIDs) in a cavity. The gate operations are
realized within the two lower flux states of the SQUIDs by using a quantized cavity field and classical microwave pulses.
Our scheme is achieved without any type of measurement, does not use the cavity mode as the data bus and only requires a very
short resonant interaction of the SQUID-cavity system. As an application of the QCPG operation, we also propose a scheme for
generating the cluster
states of many SQUIDs. 相似文献
15.
Y. Cao A. M. Wang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(1):159-166
We classify 4-qubit pure states under the stochastic
local operation and classical communication (SLOCC). There exist
twenty three essentially different classes of states, giving rise to
a four-graded partially ordered structure. We also give the
criterion to judge which class an arbitrary 4-qubit state belongs
to. We re-classify the 4-qubit pure state into 2×2×4,
4×4 aspects. Finally, we give our analysis of the
classification difference of methods for the 3-qubit pure state. 相似文献
16.
C. S. Yu X. X. Yi H. S. Song 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(2):273-278
For a tripartite pure state superposed by two individual states, the bipartitely shared entanglement can always be achieved
by local measurements of the third party. Consider the different aims of the third party, i.e. maximizing or minimizing the
bipartitely shared entanglement, we find bounds on both the possible bipartitely shared entanglement of the superposition
state in terms of the corresponding entanglement of the two states being superposed. In particular, by choosing the concurrence
as bipartite entanglement measure, we obtain calculable bounds for tripartite (2 ⊗ 2 ⊗ n)-dimensional cases. 相似文献
17.
M. Ban 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(1):147-155
Decoherence of nonclassical properties is studied for a photon system interacting with a transient environment which changes
from a linear attenuator to amplifier during the time evolution. The sufficient condition for quadrature squeezing, sub-Poissonian
photon statistics and entanglement to be completely destructed during the time-evolution is derived. The results are compared
with those obtained for another model of the transient linear amplifier. Furthermore the decoherence caused by a environment
which switches a linear amplifier to attenuator is also investigated. 相似文献
18.
Quantum state sharing of an arbitrary
multiqubit state using nonmaximally entangled GHZ states 总被引:1,自引:0,他引:1
Z.-X. Man Y.-J. Xia N. B. An 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(2):333-340
We explicitly present a scheme for quantum
state sharing of an arbitrary multiqubit state using nonmaximally
entangled GHZ states as the quantum channel and generalized Bell
states as the measurement basis. The scheme succeeds only
probabilistically with its total success probability depending on
the degree of entanglement matching between the quantum channel and
the generalized Bell states. Security of the scheme is guaranteed by
the fact that attacks of an outside eavesdropper or/and an inside
dishonest party will inevitably introduce detectable errors. 相似文献
19.
J. Ren S. Zhu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,50(1):103-105
The fidelity and entanglement entropy in an
antiferromagnetic-ferromagnetic alternating Heisenberg chain are
investigated by using the method of density-matrix
renormalization-group. The effects of anisotropy on fidelity and
entanglement entropy are investigated. The relations between
fidelity, entanglement entropy and quantum phase transition are
analyzed. It is found that the quantum phase transition point can be
well characterized by both the ground-state entropy and fidelity for
large system. 相似文献
20.
Quantum state sharing of an arbitrary two-qubit state
with two-photon entanglements and Bell-state measurements 总被引:4,自引:0,他引:4
F.-G. Deng X.-H. Li C.-Y. Li P. Zhou H.-Y. Zhou 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,39(3):459-464
Two schemes for sharing an arbitrary two-qubit state based on
entanglement swapping are proposed with Bell-state measurements
and local unitary operations. One is based on the quantum channel
with four Einstein-Podolsky-Rosen (EPR) pairs shared in advance.
The other is based on a circular topological structure, i.e., each
user shares an EPR pair with his neighboring one. The advantage of
the former is that the construction of the quantum channel between
the agents is controlled by the sender Alice, which will improve
the security of the scheme. The circular scheme reduces the
quantum resource largely when the number of the agents is large.
Both of those schemes have the property of high efficiency as
almost all the instances can be used to split the quantum
information. They are more convenient in application than the
other schemes existing as they require only two-qubit
entanglements and two-qubit joint measurements for sharing an
arbitrary two-qubit state. 相似文献