Multi-state Quantum Teleportation via One Entanglement State

A multi-sender-controlled quantum teleportation scheme is proposed to teleport several secret quantum states from different senders to a distance receiver based on only one Einstein-Podolsky-Rosen (EPR) pair with controlled-NOT (CNOT) gates. In the present scheme, several secret single-qubit quantum states are encoded into a multi-qubit entangled quantum state. Two communication modes, i.e., the detecting mode and the message mode, are employed so that the eavesdropping can be detected easily and the teleported message may be recovered efficiently. It has an advantage over teleporting several different quantum states for one scheme run with more efficiency than the previous quantum teleportation schemes.     

Multi-state Quantum Teleportation via One Entanglement State

A multi-sender-controlled quantum teleportation scheme is proposed to teleport several secret quantum states from different senders to a distance receiver based on only one Einstein-Podolsky-Rosen （EPR） pair with controlled-NOT （CNOT） gates. In the present scheme, several secret single-qubit quantum states are encoded into a multi-qubit entangled quantum state. Two communication modes, i.e., the detecting mode and the message mode, are employed so that the eavesdropping can be detected easily and the teleported message may be recovered efficiently. It has an advantage over teleporting several different quantum states for one scheme run with more efficiency than the previous quantum teleportation schemes.     

Many-Agent Controlled Teleportation of Multi-qubit Quantum Information via Quantum Entanglement Swapping

We present a method to teleport multi-qubit quantum information in an easy way from a sender to a receiver via the control of many agents in a network. Only when all the agents collaborate with the quantum information receiver can the unknown states in the sender＇s qubits be fully reconstructed in the receiver＇s qubits. In our method, agents＇s control parameters are obtained via quantum entanglement swapping. As the realization of the many-agent controlled teleportation is concerned, compared to the recent method [G.P. Yang, et al., Phys. Rev. A 70 （2004） 022329], our present method considerably reduces the preparation difficulty of initial states and the identification difficulty of entangled states, moreover, it does not need local Hadamard operations and it is more feasible in technology.     

Many-Agent Controlled Teleportation of Multi-qubit Quantum Information via Quantum Entanglement Swapping

We present a method to teleport multi-qubit quantum information in an easy way from a sender to a receiver via the control of many agents in a network. Only when all the agents collaborate with the quantum information receiver can the unknown states in the sender‘s qubits be fully reconstructed in the receiver‘s qubits. In our method,agents‘s control parameters are obtained via quantum entanglement swapping. As the realization of the many-agent controlled teleportation is concerned, compared to the recent method [C.P. Yang, et al., Phys. Rev. A 70 (2004) 022329],our present method considerably reduces the preparation difficulty of initial states and the identification difficulty of entangled states, moreover, it does not need local Hadamard operations and it is more feasible in technology.     

Probabilistic Teleportation via Entanglement

With an arbitrary bi-particle entangled mixed state which is shared by Alice (the sender) and Bob (the receiver) acted as a quantum channel, at first, a teleportation protocol that Alice successfully transmits an unknown mixed state to Bob based on a positive operator-valued measurement (POVM) is presented. The upper bound of probability to teleport successfully an unknown mixed state is then investigated, and conclude that it completely depends on the entanglement degree of the bi-particle entangled mixed state as a resource.     

Quantum Entanglement and Teleportation in a Vertical Quantum Dot

We study the thermal entanglement and teleportation using quantum dot as the quantum channel. We firstly investigate the evolution of entanglement in the vertical quantum dot, then focus on the effects of the important parameters of the system on the teleported fidelity under different conditions. We obtain the critical temperature of suddenly dead entanglement. Based on Bell measurements in two subspaces, the isotropy and anisotropy subspaces, we can find that the anisotropy measurements always overmatch the isotropy ones. Moreover, we obtain the high-fidelity teleportation for quantum dot as quantum channel when the parameters are adjusted. The possible applications of quantum dot are expected in quantum teleportation     

Effect of Dissipative Environments on Atomic-State Quantum Teleportation

In the paper, taking the atomic EPR entanglement states as quantum channel, we investigate the fidelity of quantum teleportation of atomic state in thermal environment and vacuum reservoir by means of quantum theory of damping-density operator approach, and the average fidelities are calculated. the resultsshow that the atomic quantum channel state |ø> = (1/2^1/2)(| 00>+ |11>) is more robust than | Φ> = (1/2^1/2)(|01> + |10>) in teleportation process when they are subject to the dissipative environments.     

Cooperative Quantum Two-Way Communications via Quantum Teleportation Based on Brown State with the Partial Entanglement Analysis

We demonstrate two explicit cooperative two-way quantum communications based on the Brown state in a forward-and-backward fashion. One realizes the duplex exchange of an arbitrary unknown state and a certain state between Alice and Bob with the aid of the trusty Charlie via the partial entanglement analysis. The other realizes the half-duplex exchange of arbitrary unknown states. Their securities are both guaranteed due to the fact that each participant either faithfully recovers the transmitted unknown states after performing some suitable unitary operations in a deterministic way or, in a case of any irregularity, generates no results. In addition, the present half-duplex cooperative quantum communication can be similarly extended for transmitting arbitrary unknown states via the two-way quantum teleportation based on the generalized Brown-like state in a probabilistic way.     

Entanglement Teleportation via Two-Qubit Spin Squeezing Model

Entanglement teleportation via two spins coupled to each other by one axis twisting spin squeezing interaction is investigated. We mainly concentrate on the properties of the channel entanglement, the output entanglement and the teleportation fidelity. It shows that the output entanglement increases linearly with increasing the value of the input entanglement. With the increasing of T, the teleportated entanglement increases sharply from zero to a maximum value and then decreases slowly to zero when the temperature is improved to one threshold value of T _c , and the threshold value of T _c increases with the increasing of the input entanglement. When enlarging the external magnetic, F _a firstly decreases quickly to a minimum value as the critical magnetic field Ω _c is reached, then it increases abruptly to a maximum value and finally it will be a certain value. Besides, the critical external magnetic Ω _c increases when μ is larger. For Ω<Ω _c the value of the average fidelity increases with the increasing of μ, but for Ω>Ω _c the value of it decreases from a maximum value. The influence of T on the average fidelity is similar with μ.     

Controlled Teleportation of Multi-qutrit Quantum Information by Swapping Entanglement

We present a scheme for teleporting multi-qutrit quantum information from a sender to a receiver via the control of many agents in a network. Agents＇s control parameters are obtained via quantum entanglement swapping. In our scheme, Zhang and Man＇s QSS protocol [Phys. Rev. A 72 （2005） 022303] based on Bell-state entanglement swapping is generalized to a qutrit case. Our scheme owns the advantage of having higher code capacity and better security than the work [Commun. Theor. Phys. 44 （2005） 847] on controlled teleportation for multi-qubit.     

Controlled Teleportation of Multi-qudit Quantum Information by Entanglement Swapping

In this paper, we present a scheme for teleporting multi-qudit quantum state, from the sender Alice to the receiver Charlie via many controllers Bobs, whose control parameters are obtained using entanglement swapping of maximally d-dimensional EPR pair. In our scheme, Yang＇s qutrit controlled teleportation protocol [Commun. Theor. Phys. 49 （2008） 338] based on Bell-state entanglement swapping is generalized to the qudit case. The scheme of multi-qudit owns the advantage of having higher code capacity and better security than that of multi-qutrit.     

Entanglement Teleportation Via Two-Qubit Channel Under the Non-Markovian Environment

Entanglement teleportation via a two-qubit quantum channel under the non-Markovian environment is investigated in detail. We mainly concentrate on the effects about the channel initial states and decoherence environment on the entanglement of the output state C _out and the average fidelity F _a. It is shown that for different channel initial states with increasing noise environment parameters the teleportated entanglement is initially decreased from the maximum value to a minimum value and then undergoes a increasing tendency finally to be one constant nonzero value. The average fidelity is strongly dependent on the channel initial states and the Non-Markovian environment, tuning these parameters can make the average fidelity larger than the maximum value of classical communication 2/3. Moreover, there is a threshold time t _c , when t<t _c the average fidelity is always superior to 2/3, tuning the environment parameters and channel initial states not only can make F _a superior to 2/3 but also can broaden the region where F _a is larger than 2/3. We also obtain the analytic solution values of t _c in the limit case of γ→∞ where the non-Markovian environment reduced to the Markovian one.     

Teleportation of a Three-Particle State via Entanglement Swapping

A scheme for teleporting a three-particle state is proposed when three pairs of entang]ed particles are used as quantum channel. After a sender operates the Bell-state measurement, the original state with deterministic probability can be reconstructed when the receiver performs a corresponding measurement with unitary transformation.     

Controlled Quantum Teleportation Through Noisy GHZ Channel

In this paper, we propose two physical schemes for teleporting an unknown atomic state through noisy channel in cavity QED. The quantum channel is a noisy one -- a mixed GHZ state, which is more realistic in quantum information processing. We solve analytically a master equation in the Lindblad form with （L2,z, L3,z, L4,z）-type of noise in cavity Q, ED. A comparison between the two protocols are discussed.     

伊辛模型中量子的热纠缠和保真度

研究了伊辛模型中两个粒子在均匀和非均匀磁场中的热纠缠以及利用它作为量子信息传输的通道的传输保真度.计算出纠缠度的度量Concurrence,以及在不同种情况下呈现出来的纠缠度的表现形为.与均匀磁场相反,我们发现在非均匀磁场中传输的保真度能够得到增强,同时我们发现保真度还与耦合系数和温度有关.我们通过图形清楚地表示它们的性质,从图形中我们得出,第一:在其它条件相同的情况下,无论磁场方向是相同还是相反,它们的纠缠度都是相同的;但是当磁场方向相反时,平均保真度比均匀磁场具有更大的值.第二:为了提高纠缠和平均保真度我们可以通过选择适当的磁场强度、耦合系数和降低温度来实现.     

Continuous Variable Quantum Secret Sharing via Quantum Teleportation

A continuous variable quantum secret sharing (CVQSS) scheme is proposed by using quantum teleportation. In the scheme, the participants Bob and Charlie can recover the classical secret keys only when they cooperate. Meanwhile, the security of the CVQSS scheme is analyzed in detail by calculating the bit error rates (BERs) under different situations. It is shown that our proposed CVQSS scheme not only can resist the external attacks, but also can against the participant’s malicious attacks when the channel transmission efficiency η is above 50 %.     

单光子纠缠态的纠缠转移和量子隐形传态

使用光学分束器和单光子源,利用单光子态和真空态制备出了纠缠单光子态.利用光学分束器作用和单光子探测,实现了三个通讯伙伴之间的纠缠转移.提出了一个关于纠缠单光子态的量子隐形传态方案.在这个方案中,被传送的是一个未知的单光子纠缠态.通讯双方使用的量子信道是两个单光子纠缠态.通过使用分束器作用和对输出态进行光子测量以及在经典信息的帮助下,纠缠转移和量子隐形传态的过程被完成.     

Quantum Teleportation via Hybrid Entangled States

In this paper, we study quantum teleportation of atomic states via a hybrid entangled state (HES) involving an atom and a cavity field. And we investigate how to implement controlled phase (CP) gates between atomic internal Finally, a brief discussion about the feasibility of this scheme in experiment is presented.     

Global Positioning Scheme via Quantum Teleportation

Quantum teleportation scheme is undoubtedly an inspiring theoretical discovery as an amazing application of quantum physics, which was experimentally realized several years later. For the purpose of quantum communication via this scheme, an entangled ancillary pair shared by Alice and Bob is the essential ingredient, and a quantum memory in Bob’s system is necessary for him to keep the quantum state until the classical message from Alice arrives. Yet, the quantum memory remains a challenge in bo...