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1.
Teleportation for an Ionic Entangled Internal State by Entanglement Swapping 总被引:4,自引:0,他引:4 下载免费PDF全文
We present an effective scheme to teleport an unknown ionic entangled internal state via trapped ions without joint Bell-state measurement. In the constructed quantum channel process, we adopt entanglement swapping to avoid decrease of entanglement during the distribution of particles. Thus our scheme provides new prospects for quantum teleportation over longer distance. The distinct advantages of our scheme are that our scheme is insensitive to heating of vibrational mode and can be generalized to teleport an N-ion electronic entangled GHZ class state. Furthermore, in our scheme the success probability can reach 1. 相似文献
2.
In the system with two two-level ions confined in a linear trap,
this paper presents a simple scheme to realize the quantum phase
gate (QPG) and the swap gate beyond the Lamb--Dicke (LD) limit.
These two-qubit quantum logic gates only involve the internal states
of two trapped ions. The scheme does not use the vibrational mode as
the data bus and only requires a single resonant interaction of the
ions with the lasers. Neither the LD approximation nor the auxiliary
atomic level is needed in the proposed scheme. Thus the scheme is
simple and the interaction time is very short, which is important in
view of decoherence. The experimental feasibility for achieving this
scheme is also discussed. 相似文献
3.
An effective teleportation scheme for an unknown ionic internal state
via trapped ions is proposed without joint Bell-state measurement
(BSM). In the constructed quantum channel process, we make use of
entanglement swapping to avoid decrease in entanglement during
the distributing of particles. Thus our scheme provides new prospects
for quantum teleportation in a longer distance. The distinct
advantage of our scheme is insensitive to the heating of vibrational
mode. Furthermore, our scheme has no any individual optical access,
and the successful probability also can reach 1. 相似文献
4.
Extending the double Jaynes--Cummings model to a more
complicated case where the mode--mode competition is considered, we
investigate the entanglement character of two isolated atoms by
means of concurrence, and discuss the dependence of atom--atom
entanglement on the different initial state and the relative
coupling strength between the atom and the corresponding cavity
field. The results show that the amplitude and the period of the
atom--atom entanglement evolution can be controlled by the choice of
initial state and relative coupling strength, respectively. We find
that the phenomenon of entanglement sudden death (ESD) is sensitive
to the initial conditions. The length of the time interval for
zero entanglement depends not only on the initial degree of
entanglement between two atoms but also on the relative coupling
strength of atom--field interaction. The ESD effect can be weakened
by enhancing the mode--mode competition between the three- and
single-photon processes. 相似文献
5.
We study three-body entanglement induced by spontaneous
emission in a three two-level atoms system by using the entanglement
tensor approach. The results show that the amount of entanglement
is strongly dependent on the initial state of the system and the species
of atoms. The three-body entanglement is the result of the coherent
superposition of the two-body entanglements. The larger the
two-body entanglement is, the stronger the three-body entanglement
is. On the other hand, if there exists a great difference in three two-body entanglement measures,
the three-body entanglement is very weak.
We also find that the maximum of the two-body entanglement
obtained with nonidentical atoms is greater than that obtained
with identical atoms via adjusting the difference in atomic frequency. 相似文献
6.
A system consisting of two atoms interacting with a
two-mode vacuum is considered, where each atom is resonant with the
two cavity modes through two different competing transitions. The
effect of mode--mode competition on the atom--atom entanglement is
investigated. We find that the entanglement between the two atoms
can be induced by the mode--mode competition. For the initial atomic
state |\varPsi(0)\rangle, whether the atoms are initially
separated or entangled, a large or even maximal entanglement between
them can be obtained periodically by introducing the mode--mode
competition. For the initial atomic state |\varPhi(0)\rangle, the
strong mode--mode competition can prevent the two atoms entangled
initially from suffering entanglement sudden death; besides, it
makes them in a more stable and longer-lived entanglement than in
the non-competition case. 相似文献
7.
Fast scheme for generating quantum-interference states and GHZ state of N trapped ions 总被引:1,自引:0,他引:1 下载免费PDF全文
We propose a fast scheme to generate the quantum-interference states
of N trapped ions. In the scheme the ions are driven by a
standing-wave laser beam whose carrier frequency is tuned such that
the ion transition can take place. We also propose a simple and fast
scheme to produce the GHZ state of N hot trapped ions and this
scheme is insensitive to the heating of vibrational motion, which is
important from the viewpoint of decoherence. 相似文献
8.
A scheme for conditional quantum phase gate viabimodal cavity and a Λ-type three-level atom 下载免费PDF全文
We propose a scheme to implement a two-qubit conditional quantum
phase gatefor the intracavity field viaa single three-level
$\Lambda$-type atom driven by two modes in a high-Q cavity. The
quantum information is encoded on the Fock states of the bimodal
cavity. The gate's averaged fidelity is expected to reach $99.8\%$. 相似文献
9.
Quantum Entanglement in a System of Two Spatially Separated Atoms Coupled to the Thermal Reservoir 下载免费PDF全文
We study quantum entanglement between two spatially separated atoms coupled to the thermal reservoir. The influences of the initial state of the system, the atomic frequency difference and the mean number of the thermal field on the entanglement are examined. The results show that the maximum of the entanglement obtained with nonidentical atoms is greater than that obtained with identical atoms. The degree of entanglement is progressively decreased with the increase of the thermal noise. Interestingly, the two atoms can be easily entangled even when the two atoms are initially prepared in the most mixed states. 相似文献
10.
The entanglement of two dipole--dipole coupled atoms interacting with a thermal field via a two-photon process 下载免费PDF全文
This paper studies entanglement between two dipole-dipole coupled atoms interacting with a thermal field via a two-photon process. It shows that the entanglement is dependent on the mean photon number of the thermal field and the dipole-dipole interaction. The results also show that the atom-atom entanglement through the two-photon process is larger than that through the one-photon process and a remarkable amount of entanglement between the atoms still remains at certain times even for a very highly noisy thermal field. 相似文献