Controlled Teleportation of an Arbitrary Multi-Qudit State in a General Form with d-Dimensional Greenberger-Horne-Zeilinger States

A general scheme for controlled teleportation of an arbitrary multi-qudit state with d-dimensional Greenberger- Horne--Zeilinger （GHZ） states is proposed. For an arbitrary m-qudit state, the sender Alice performs m generalized Bell-state projective measurements on her 2m qudits and the controllers need only take some single-particle measurements. The receiver Charlie can reconstruct the unknown m-qudit state by performing some single-qudit unitary operations on her particles if she cooperates with all the controllers. As the quantum channel is a sequence of maximally entangled GHZ states, the intrinsic efticiency for qudits in this scheme approaches 100% in principle.

Quantum Oblivious Transfer with Reusable Bell State

In cryptography,oblivious transfer(OT)is an important multiparty cryptographic primitive and protocol,that is suitable for many upperlayer applications,such as secure computation,remote coin-flipping,electrical contract signing and exchanging secrets simultaneously.However,some nogo theorems have been established,indicating that one-out-of-two quantum oblivious transfer(QOT)protocols with unconditional security are impossible.Fortunately,some one-out-of-two QOT protocols using the concept of Crepeau’s reduction have been demonstrated not to conform to Lo’s no-go theorem,but these protocols require more quantum resources to generate classical keys using all-or-nothing QOT to construct one-out-of-two QOT.This paper proposes a novel and efficient one-out-of-two QOT which uses quantum resources directly instead of wasting unnecessary resources to generate classical keys.The proposed protocol is not covered by Lo’s no-go theorem,and it is able to check the sender’s loyalty and avoid the attack from the receiver.Moreover,the entangled state of the proposed protocol is reusable,so it can provide more services for the participants when necessary.Compared with otherQOT protocols,the proposed protocol is more secure,efficient,and flexible,which not only can prevent external and internal attacks,but also reduce the required resources and resource distribution time.

记忆泡利信道下Bell态的几何失协

几何失协是度量量子关联的一种重要方法.通过引入记忆参数,使得泡利噪声具有记忆性,此时噪声被定义为记忆泡利噪声.依据不同记忆泡利信道的噪声参数,讨论xz退相位噪声、去极化噪声、双泡利噪声以及3种翻转噪声下Bell态的几何失协,得到Bell态的几何失协与噪声参数之间的关系,并且分析记忆参数对几何失协的影响.结果表明,在记忆泡利信道下Bell态的几何失协受到噪声影响的程度更小,即记忆泡利信道可有效增强噪声影响下Bell态几何失协的稳定性.这表明记忆泡利信道可以捕获更多的信息,有利于节约量子资源.

Scattering states of modified PSschl-Teller potential in D-dimension

We present a new approximation scheme for the centrifugal term, and apply this new approach to the SchrSdinger equation with the modified P5schl Teller potential in the -dimension for arbitrary angular momentum states. The approximate analytical solutions of the scattering states are derived. The normalized wave functions expressed in terms of the hypergeometric functions of the scattering states on the 2 scale and the calculation formula of the phase shifts are given. The numerical results show that our results are in good agreement with those obtained by using the amplitude-phase method （APM）.

Scattering states of modified Pschl-Teller potential in D-dimension

We present a new approximation scheme for the centrifugal term,and apply this new approach to the Schrdinger equation with the modified Pschl-Teller potential in the D-dimension for arbitrary angular momentum states.The approximate analytical solutions of the scattering states are derived.The normalized wave functions expressed in terms of the hypergeometric functions of the scattering states on the k/2π scale and the calculation formula of the phase shifts are given.The numerical results show that our results are in good agreement with those obtained by using the amplitude-phase method(APM).

Controlled quantum teleportation with Bell states

We propose a new scheme for controlled quantum teleportation with Bell states in which classical keys for controllers＇ portion are used. We also discuss the security of the proposed scheme and show that it can satisfy the requirements for controlled quantum teleportation. The comparison between this scheme and the previous ones shows that it is more economical and efficient.

Dynamic quantum secret sharing protocol based on two-particle transform of Bell states

To solve the problems of updating sub-secrets or secrets as well as adding or deleting agents in the quantum secret sharing protocol, we propose a two-particle transform of Bell states, and consequently present a novel dynamic quantum secret sharing protocol. The new protocol can not only resist some typical attacks, but also be more efficient than the existing protocols. Furthermore, we take advantage of the protocol to establish the dynamic secret sharing of a quantum state protocol for two-particle maximum entangled states.

Multiparty Quantum Secret Sharing Using Two-Photon Three-Dimensional Bell States

We present a two-photon three-dimensional multiparty quantum secret sharing scheme.The secret messagesare encoded by performing local operations.This is different from those quantum secret sharing protocols that all sharersmust make a state measurement.The merit of our protocol is the high capacity.

A novel quantum information hiding protocol based on entanglement swapping of high-level Bell states

Using entanglement swapping of high-level Bell states, we first derive a covert layer between the secret message and the possible output results of the entanglement swapping between any two generalized Bell states, and then propose a novel high-efficiency quantum information hiding protocol based on the covert layer. In the proposed scheme, a covert channel can be built up under the cover of a high-level quantum secure direct communication （QSDC） channel for securely transmitting secret messages without consuming any auxiliary quantum state or any extra communication resource. It is shown that this protocol not only has a high embedding efficiency but also achieves a good imperceptibility as well as a high security.

Fault tolerant deterministic secure quantum communication using logical Bell states against collective noise

This study proposes two novel fault tolerant deterministic secure quantum communication （DSQC） schemes resistant to collective noise using logical Bell states. Either DSQC scheme is constructed based on a new coding function, which is designed by exploiting the property of the corresponding logical Bell states immune to collective-dephasing noise and collective-rotation noise, respectively. The secret message can be encoded by two simple unitary operations and decoded by merely performing Bell measurements, which can make the proposed scheme more convenient in practical applications. Moreover, the strategy of one-step quanta transmission, together with the technique of decoy logical qubits checking not only reduces the influence of other noise existing in a quantum channel, but also guarantees the security of the communication between two legitimate users. The final analysis shows that the proposed schemes are feasible and robust against various well-known attacks over the collective noise channel.

Complete Bell-state analysis for a single-photon hybrid entangled state

We propose a scheme capable of performing complete Bell-state analysis for a single-photon hybrid entangled state.Our single-photon state is encoded in both polarization and frequency degrees of freedom.The setup of the scheme is composed of polarizing beam splitters,half wave plates,frequency shifters,and independent wavelength division multiplexers,which are feasible using current technology.We also show that with this setup we can perform complete two-photon Bell-state analysis schemes for polarization degrees of freedom.Moreover,it can also be used to perform the teleportation scheme between different degrees of freedom.This setup may allow extensive applications in current quantum communications.

基于d维Bell态的单态多方半量子秘密共享

本文提出了一种基于d维Bell态的单态多方半量子秘密共享(Multiparty Semiquantum Secret Sharing,MSQSS)协议,该协议可以实现“只有当所有接收方协同工作时才能恢复发送方的密钥”这一目标.该协议被证实能够抵抗外部攻击和参与者攻击.该协议适用于d维量子系统,仅采用一种d维Bell态作为初始量子资源,且既不需要量子纠缠交换,也不需要酉操作.

Anti-Noise Quantum Network Coding Protocol Based on Bell States and Butterfly Network Model

How to establish a secure and efficient quantum network coding algorithm isone of important research topics of quantum secure communications. Based on thebutterfly network model and the characteristics of easy preparation of Bell states, a novelanti-noise quantum network coding protocol is proposed in this paper. The new protocolencodes and transmits classical information by virtue of Bell states. It can guarantee thetransparency of the intermediate nodes during information, so that the eavesdropper Evedisables to get any information even if he intercepts the transmitted quantum states. Inview of the inevitability of quantum noise in quantum channel used, this paper analyzesthe influence of four kinds of noises on the new protocol in detail further, and verifies theefficiency of the protocol under different noise by mathematical calculation and analysis.In addition, based on the detailed mathematical analysis, the protocol has functioned wellnot only on improving the efficiency of information transmission, throughput and linkutilization in the quantum network, but also on enhancing reliability and antieavesdroppingattacks.

Controlled teleportation of high-dimension quantumstates with generalized Bell-state measurement

In this paper a scheme for controlled teleportation of arbitrary high-dimensional unknown quantum states is proposed by using the generalized Bell-basis measurement and the generalized Hadamard transformation. As two special cases, two schemes of controlled teleportation of an unknown single-qutrit state and an unknown two-qutrit state are investigated in detail. In the first scheme, a maximally entangled three-qutrit state is used as the quantum channel, while in the second scheme, an entangled two-qutrit state and an entangled three-qutrit state are employed as the quantum channels. In these schemes, an unknown qutrit state can be teleported to either one of two receivers, but only one of them can reconstruct the qutrit state with the help of the other. Based on the case of qutrits, a scheme of controlled teleportation of an unknown qudit state is presented.

A novel scheme of hybrid entanglement swapping and teleportation using cavity QED in the small and large detuning regimes and quasi-Bell state measurement method

We outline a scheme for entanglement swapping based on cavity QED as well as quasi-Bell state measurement(quasiBSM) methods. The atom–field interaction in the cavity QED method is performed in small and large detuning regimes.We assume two atoms are initially entangled together and, distinctly two cavities are prepared in an entangled coherent–coherent state. In this scheme, we want to transform entanglement to the atom-field system. It is observed that, the fidelities of the swapped entangled state in the quasi-BSM method can be compatible with those obtained in the small and large detuning regimes in the cavity QED method(the condition of this compatibility will be discussed). In addition, in the large detuning regime, the swapped entangled state is obtained by detecting and quasi-BSM approaches. In the continuation,by making use of the atom–field entangled state obtained in both approaches in a large detuning regime, we show that the atomic as well as field states teleportation with complete fidelity can be achieved.

Indistinguishability of orthogonal time-separated bell states

This paper proves that it is impossible to identify orthogonally time-separated Bell states. If two qubits of a Bell state interact with the measurement apparatus at different time, any attempt to identify this state will disturb it.

Bell States and Two-Qubit Logic Gate with Superconducting Charge Qubits Coupling to a Nanomechanical Resonator

We propose a scheme for generating Bell states involving two SQUID-based charge qubits by coupling themto a nanomechanical resonator.We also show that it is possible to implement a two-qubit logic gate between the twocharge qubits by choosing carefully the interaction time.

Degree of Entanglement and Violation of Bell Inequality by Two-Spin-1/2 States

Bell inequality is violated by the quantum mechanical predictions made from an entangled state of the composite system. In this paper we examine this inequality and entanglement measures in the construction of the coherent states for two-qubit pure and mixed states, we find a link to some entanglement measures through some new parameters （amplitudes of coherent states）. Conditions for maximal entanglement and separability are then established for both pure and mixed states. Finally, we analyze and compare the violation of Bell inequality for a class of mixed states with the degree of entanglement by applying the formalism of Horodecki et al.

Perfect Quantum Teleportation via Bell States

Quantum mechanics shows superiority than classical mechanics in many aspects and quantum entanglement plays an essential role in information processing and some computational tasks such as quantum teleportation(QT).QT was proposed to transmit the unknown states,in which EPR pairs,the entangled states,can be used as quantum channels.In this paper,we present two simple schemes for teleporting a product state of two arbitrary single-particle and an arbitrary two-particle pure entangled state respectively.Alice and Bob have shared an entangle state.Two Bell states are used as quantum channels.Then after Alice measuring her qubits and informing Bob her measurement results,Bob can perfectly reconstruct the original state by performing corresponding unitary operators on his qubits.It shown that a product state of two arbitrary single-particle and an arbitrary two-particle pure entangled state can be teleported perfectly,i.e.the success probabilities of our schemes are both 1.

Entropy of Field Interacting With Two Atoms in Bell State

In this paper, we investigate entropy properties of the single-mode coherent optical field interacting with the two two-level atoms initially in one of the four Bell states. It is found that the different initial states of the two atoms lead to different evolutions of field entropy and the intensity of the field plays an important role for the evolution properties of field entropy.