Probabilistic Teleportation of a Four-Particle Entangled W State

In this paper, two schemes for teleporting an unknown four-particle entangled W state is proposed. In the first scheme, two partial entangled four-particle states are used as quantum channels, while in the second scheme,four non-maximally entangled particle pairs are considered as quantum channels. It is shown that the teleportation can be successfully realized with certain probability, for both schemes, if a receiver adopts some appropriate unitary transformations. It is also shown that the successful probabilities of these two schemes are different.

Remote State Preparation of a Greenberger-Horne-Zeilinger Class State

In this paper, we propose a scheme for the remote preparation of a three-particle Greenberger-HorneZeilinger class state by a two-particle entangled state and a three-particle entangled state. It is shown that, by this scheme, only two classical bits and one two-particle projective measurement are enough for such preparation.

Channel＇s Concurrence and Quantum Teleportation

Concurrence can measure the entanglement property of a system. If the channel is a pure state, positive concurrence state can afford the good performance in the teleportation process. If the channel ia a mixed state, positive concurrence state cannot assure the good performance in the teleportation. The conditions of the positive concurrence and the quantum teleportation in the Heisenberg spin ring is derived.

Preparation of a New Type of Multiqubit Entangled States in Cavity QED

Recently Yang,Chu,and Han [Phys.Rev.A 70 (2004) 022329] presented a new type of multipartiteentangled states for implementing efficient many-party controlled teleportation of multiqubit quantum information.Herewe propose a simple scheme for preparing such a type of multi-atom entangled states in cavity quantum electrodynamics(QED).The scheme involves atom-cavity interaction with large detuning,and is immune to the cavity decay and thethermal field states.Some practical analyses show its availability with the present technology.

Multi-mode Einstein-Podolsky-Rosen Entangled State Representation and Its Applications

Our primary purpose of this work is to explicitly construct the general multiparite Einstein-Podolsky- Rosen （EPR） entangled state in multi-mode Fock space for a system with different masses of particles, which makes up a new quantum mechanical representation owing to completeness relation and orthogonal property. Its entanglement can be seen more clearly by analyzing its standard Schmidt decomposition. In addition, some applications of the multipartite entanglement are proposed including deriving the generalized Wigner operator and squeezing operator.

Quantum Statistical Properties of Binomial Field Interacting with Two Entangled Atoms

Quantum statistical properties of the binomial field interacting with the two entangled atoms are investi-gated for the different initial conditions.It is found that the sub-Poissonian distribution and the antibunching effect canbe presented for the certain ranges of the involved parameters.

Study on Quantum Entanglement Between Mesoscopic Circuit and Environment at Coherent State

Taking into account the interaction between electrons and phonons, in the case without-rotating-wave aproximation, we study the entangling property between the mesoscopic circuit and environment at coherent state or equilibrium state. The result indicates that, in long time limit t →∞, the averages of charge and current in the circuit only depend on the average of the system at the initial state when the environment is initially at thermal equilibrimn. However, when the environment is initially at coherent state, the average of charge and current in the circuit is determined by the specific coherent state ensemble. Generally speaking, the entanglement between the circuit and environment will lead to the quantum state purity declining of the circuit, then the circuit emerges decoherent phenomenon, and so a mixed sta.te appears. Purity changes are related to the initial quantum state of environment and circuit. With the further evolution of time, coherence will be gradually restored, but cannot return to 1.

Angular Momentum Phase State Representation for Quantum Pendulum

To consummate the quantum pendulum theory whose Hamiltonian takes bosonic operator formalism and manifestly exhibits its dynamic behaviour in the entangled state representation, we introduce angular momentum state representation and phase state representation. It turns out that the angular momentum state is the partial wave expansion of the entangled state.

State-Independent Proofs of Bell＇s Theorem Without Inequalities and Bell Inequality for Four-Qubit System

A state-dependent proof of Bell's theorem without inequalities using the product state of any two maximally entangled states (Bell states) of two qubits for two observers in an ideal condition, each of which possesses two qubits,is proposed. It is different from the other proofs in which there exists a fundamental requirement that certain specific suitable Bell states have been chosen. Moreover, in any non-ideal situation, a common Bell inequality independent of the choices of the 16-product states is derived, which is used to test the contradiction between quantum mechanics and local reality theory in the reach of current experimental technology.

A Generalized Hankel Transformation Derived by Parametrized Entangled State Representations

Using the parametrized entangled state representations we have found a generalized Hankel transformationwith the integral kernel being a combination of Bessel functions.This generalized Hankel transformation corresponds tothe appropriate quantum mechanical representation transformation.

Entanglement of Para-Bose Entangled Coherent States and Probabilistic Teleportation

We study the entanglement of the para-Bose entangled coherent states by adopting the entanglement of formation and propose a scheme of probabilistic teleportation via para-Bose entangled coherent states. It is found that the mean fidelity of the scheme increases with the decrease of the para-Bose parameter ho in the case of non-maximally entangled para-Bose entangled coherent states.

Controlled Remote Preparing of an Arbitrary 2-Qudit State with Two-Particle Entanglements and Positive Operator-Valued Measure

We present a scheme for symmetric controlled remote preparation of an arbitrary 2-qudit state form a sender to either of the two receivers via positive operator-valued measurement and pure entangled two-particle states. The first sender transforms the quantum channel shared by all the agents via POVM according to her knowledge of prepared state. All the senders perform singIe- or two-particle projective measurements on their entangled particles and the receiver can probabilisticaly reconstruct the original state on her entangled particles via unitary transformation and auxiliary qubit. The scheme is optimal as the probability which the receiver prepares the original state equals to the entanglement of the quantum channel. Moreover, it is more convenience in application than others as it requires only two-particle entanglements for preparing an arbitrary two-qudit state.

Entangler and analyzer for multiphoton Greenberger-Horne-Zeilinger states using weak nonlinearities

In the regime of weak nonlinearity we present two general,feasible schemes for manipulating photon states.One is an entangler for generating any one of the n-photon Greenberger-Horne-Zeilinger(GHZ)states.Interactions of the incoming photons with crossKerr media followed by a phase shift gate and a measurement on a probe beam plus appropriate local operations using classical feed-forward of the measurement results allow one to obtain the desired states in a nearly deterministic manner.The second scheme discussed is an analyzer for multiphoton maximally entangled states,which is derived from the above entangler.In this scheme,all of the 2nn-photon GHZ states can,nearly deterministically,be discriminated.