Hierarchical Quantum Information Splitting with Six-Photon Cluster States

We propose a scheme for hierarchical quantum information splitting with the recently realized six-photon cluster state (Lu et al. in Nat. Phys. 3:91, 2007), where a Boss distributes a quantum secret (quantum state) to five distant agents who are divided into two grades. Two agents are in the upper grade and three agents are in the lower grade. An agent of the upper grade only needs the collaboration of two of the other four agents for getting the secret, while an agent of the lower grade needs the collaboration of all the other four agents. In other words, the agents of two grades have different authorities to recover Boss’s secret.     

Hierarchical and probabilistic quantum state sharing via a non-maximally entangled |χ〉 state

A scheme that probabilistically realizes hierarchical quantum state sharing of an arbitrary unknown qubit state with a four-qubit non-maximally entangled |χ state is presented in this paper. In the scheme, the sender Alice distributes a quantum secret with a Bell-state measurement and publishes her measurement outcomes via a classical channel to three agents who are divided into two grades. One agent is in the upper grade, while the other two agents are in the lower grade. Then by introducing an ancillary qubit, the agent of the upper grade only needs the assistance of any one of the other two agents for probabilistically obtaining the secret, while an agent of the lower grade needs the help of both the other two agents by using a controlled-NOT operation and a proper positive operator-valued measurement instead of the usual projective measurement. In other words, the agents of two different grades have different authorities to reconstruct Alice’s secret in a probabilistic manner. The scheme can also be modified to implement the threshold-controlled teleportation.     

Hierarchical Controlled Remote State Preparation by Using a Four-Qubit Cluster State

We propose a scheme for hierarchical controlled remote preparation of an arbitrary single-qubit state via a four-qubit cluster state as the quantum channel. In this scheme, a sender wishes to help three agents to remotely prepare a quantum state, respectively. The three agents are divided into two grades, that is, an agent is in the upper grade and other two agents are in the lower grade. In this process of remote state preparation, the agent of the upper grade only needs the assistance of any one of the other two agents for recovering the sender’s original state, while an agent of the lower grade needs the collaboration of all the other two agents. In other words, the agents of two grades have different authorities to reconstruct sender’s original state.     

Efficient multi-party quantum state sharing of an arbitrary two-qubit state

We present an efficient scheme for sharing an arbitrary two-qubit quantum state with n agents. In this scheme, the sender Alice first prepares an n + 2-particle GHZ state and introduces a Controlled-Not (CNOT) gate operation. Then, she utilizes the n + 2-particle entangled state as the quantum resource. After setting up the quantum channel, she performs one Bell-state measurement and another single-particle measurement, rather than two Bell-state measurements. In addition, except that the designated recover of the quantum secret just keeps two particles, almost all agents only hold one particle in their hands respectively, and thus they only need to perform a single-particle measurement on the respective particle with the basis X. Compared with other schemes based on entanglement swapping, our scheme needs less qubits as the quantum resources and exchanges less classical information, and thus obtains higher communication efficiency.     

Controlled quantum state sharing of arbitrary two-qubit states with five-qubit cluster states

In this paper, we propose a controlled quantum state sharing scheme to share an arbitrary two-qubit state using a five-qubit cluster state and the Bell state measurement. In this scheme, the five-qubit cluster state is shared by a sender (Alice), a controller (Charlie), and a receiver (Bob), and the sender only needs to perform the Bell-state measurements on her particles during the quantum state sharing process, the controller performs a single-qubit projective measurement on his particles, then the receiver can reconstruct the arbitrary two-qubit state by performing some appropriate unitary transformations on his particles after he has known the measured results of the sender and the controller.     

Quantum secret sharing protocol with four state Grover algorithm and its proof-of-principle experimental demonstration

In this article, we propose a three-party quantum secret sharing protocol with four-state Grover algorithm. The protocol has several advantages. It uses only four initial states which simplifies its experimental implementation. It has a higher encoding capacity, each two-qubit state provides two bits of information. We have experimentally demonstrated the protocol in a nuclear magnetic resonance quantum information processor successfully.     

Cryptanalysis and Improvement of a Multiparty Quantum Direct Secret Sharing of Classical Messages with Bell States and Bell Measurements

Recently, a multiparty quantum direct secret sharing protocol with Bell states was presented (Song et al., Int. J Theor. Phys. 57, 1559, 2018). In this protocol, the secret message of the dealer is directly encoding into the transmitted particles. All agents obtain their pieces of secret by making Bell state measurement on their receiving particles, then cooperate to recover the dealer’s secret. However, as we show, this protocol is insecure, because an outside attacker or two special dishonest agents can eavesdrop the secret fully. Furthermore, an improved version of this protocol is proposed, which can stand against the presented attacks.

     

Three-Party Quantum Information Splitting of an Arbitrary Two-Qubit State by Using Six-Qubit Cluster State

We propose a scheme for splitting an arbitrary two-qubit state among three parties by using a six-qubit cluster-class state as a quantum channel. Based on two Bell-state measurements (BSMs) and a two-qubit projective measurement, any one of the two agents can reconstruct the original state if he/she collaborates with the other one, whilst individual agent obtains no information.     

Participant attack on quantum secret sharing based on entanglement swapping

The security of quantum secret sharing based on entanglement swapping is revisited and a participant attack is presented. In this attack two dishonest agents together can illegally recover the secret quantum state without the help of any other controller, and it will not be detected by any other users. Furthermore, by modifying the distribution process of particles and adding a detection step after each distribution process, we propose an improved protocol which can resist this kind of attack.     

Two schemes of multiparty quantum direct secret sharing via a six-particle GHZ state

In this paper, two new efficient multiparty quantum direct secret sharing schemes are proposed via a six-particle GHZ state and Bell measurements. In the first scheme, based on the theory of security cryptanalysis, the secret message of the sender is directly encoded into the transmitted particles, and all the agents can obtain their information by performing bell measurement on the received particles, and then cooperate to recover the information of the sender. In the second scheme, we define a new secret shared coding method by performing local unitary operations on the transmitted particles, then agents perform Bell measurements on their own particles respectively, and feedback the measurement to the dealer. If the agent's results are matched with the previous coding method, the protocol will work out.In addition, the proposed two schemes have the following common advantages: the sender can send all prepared particles to the receiver, and can send an arbitrary key to the receiver, rather than a random secret key; the proposed schemes do not need to insert any detection sets to detect eavesdropping and can resist both existing attacks and spoofing attacks by dishonest agents. The sender need not to retain any photons, so the sender's quantum memory could be omitted here.     

Quantum Secure Direct Communication with Cluster State

We propose a novel protocol for quantum secure direct communication with cluster states. In this protocol, the two legitimate users, Alice and Bob, can directly transmit the secret messages by using the Bell-basis measurement and Z-basis measurement, respectively, in classical communication. Since our quantum secure direct communication protocol is based on the cluster state, it is easily processed by a one-way quantum computer.     

Deterministic Remote Entangled State Preparation Using Cluster State in Cavity QED

We propose a scheme to prepare a two-qubit remote entangled state based on four-qubit cluster state in cavity quantum electrodynamics which involves the interaction of the atoms with the cavity. Through using four-particle cluster state as a quantum channel, we shown that the probability and fidelity of the successful remote state preparation can approach unit. In addition, our protocol only need single qubit measurement instead of the conventional Bell-state measurement, then it is quite simple but also very robust to the cavity decay and the influence of the thermal field.     

Faithful Multihop Two-Qubit Transmission Through GHZ-GHZ Channel

Quantum teleportation is an important method for transmitting quantum states between two quantum communication nodes. In this paper, we propose a low-latency quantum communication scheme based on Greenberger-Horne-Zeilinger (GHZ) state. To implement two-qubit transmission, the source and all intermediate nodes perform quantum measurements simultaneously and the measurement results are transmitted to the destination node through classical channel independently. The destination node performs appropriate unitary operation on its particles to recover the original two-qubit state based on received measurement results. Our scheme effectively reduces the end-to-end quantum communication delay.

     

Splitting Unknown Qubit State Using Five-Qubit Entangled State

In this paper, we demonstrate how a five-qubit entangled state can be used to realize the deterministic Quantum State Sharing (QSTS) of a single and two-qubit state among three parties by performing von-Neumann measurement and bell-state measurements. In our scheme, any of the two agents has the ability to reconstruct the original state if he/she collaborates with the other agent,otherwise an individual agent does not have enough information to reconstruct the original state. The paper also outlines the various measurements and mathematical framework of the scheme. The security analysis of our scheme against two attacks scenarios prove that the scheme is secure against an eavesdropper attack and a malicious attacks.     

基于非最大纠缠的五粒子Cluster态的高效量子态共享方案

本文提出了一个新的未知量子态共享方案,使用一个非最大纠缠的五粒子Cluster态作为量子通道来实现任意两粒子未知量子态的共享. 即就是发送方（Alice）,接收方（Bob）和控制方（Charlie）共享一个非最大纠缠的五粒子Cluster态. 与以前传统方案不同,在本方案中发送方引入一个辅助粒子,并对其手中的粒子进行正交完备基测量,而接收方不需要引入辅助粒子,只需要执行适当的幺正操作,即可以方便的完成信息的顺利接收. 控制方通过对自己手中的粒子做单粒子投影测量来控制和协助通信双方,使得任意两粒子的未知量子态共享方案得以成功实现. 关键词： 量子态共享 五粒子Cluster态 正交完备基测量 单粒子投影测量     

Quantum Splitting a Two-qubit State with a Genuinely Entangled Five-qubit State

A new application of the genuinely entangled five-qubit state is investigated for quantum information splitting of a particular type of two-qubit state. In this scheme, a genuinely entangled five-qubit state is shared by Alice (a sender), Charlie (a controller) and Bob (a receiver), and Alice only needs to perform two Bell-state measurements and Charlie performs a single-qubit measurement, Bob can reconstruct the two-qubit state by performing some appropriately unitary transformations on his qubits after he knows the measured results of both Alice and Charlie. This quantum information splitting scheme is deterministic, i.e. the probability of success is 100 %. The presented protocol is showed to be secure against certain eavesdropping attacks.     

基于五粒子团簇态实现经济和简单的二粒子任意态的可控隐形传态

通过对五粒子团簇态新应用的研究,提出了一个经济和简单的二粒子任意态的可控隐形传态方案.在这个方案中,发送者（Alice）、控制者（Charlie）和接收者（Bob）共享一个五粒子团簇态,发送者只需要执行Bell基测量,而控制者也仅需要执行单粒子投影测量.接受者根据发送者和控制者的测量结果,对自己拥有的粒子做适当的幺正变换,就可以重建发送者的二粒子任意态.这个可控隐形传态方案是决定性的,成功的概率为100%.与使用相同的量子信道进行二粒子任意态的可控隐形传送方案相比,不需要执行多粒子的联合测量,从而使得这个方案更加简单.     

基于五粒子团簇态实现经济和简单的二粒子任意态的可控隐形传态(英文)

通过对五粒子团簇态新应用的研究,提出了一个经济和简单的二粒子任意态的可控隐形传态方案.在这个方案中,发送者(Alice)、控制者(Charlie)和接收者(Bob)共享一个五粒子团簇态,发送者只需要执行Bell基测量,而控制者也仅需要执行单粒子投影测量.接受者根据发送者和控制者的测量结果,对自己拥有的粒子做适当的幺正变换,就可以重建发送者的二粒子任意态.这个可控隐形传态方案是决定性的,成功的概率为100%.与使用相同的量子信道进行二粒子任意态的可控隐形传送方案相比,不需要执行多粒子的联合测量,从而使得这个方案更加简单.     

Controlled three-party communication using GHZ-like state and imperfect Bell-state measurement

We present a controlled three-party communication protocol using Greenberger-Horne-Zeilinger (GHZ)-like state and imperfect Bell-state measurement. Using the idea of controlled quantum teleportation, it can realize the secret information transmission between the legitimate participants under the control of the controller. It needs no unitary operation to recover the original state for the receiver, and it saves half of communication cost publicized by the sender. The order rearrangement of particles and data block transmission ensure the security of communication. With imperfect Bell-state measurement, it is tolerant of some noise effects and is feasible by using the present optical technique.     

Quantum Tasks Using Symmetric Cluster States

The cluster state has its feasibility for universal quantum computations. In this paper, we show that one symmetric cluster state can be used for the teleportation of an arbitrary two-qubit state deterministically. The one takes use of generalized Bell basis measurement while the other is completed using a general projective measurement from constructed orthogonal measurement basis and the Pauli flip measurement. Moreover, this state can also be utilized for remotely preparation of a restricted two qubit state within two different quantum network topologies, the controlled and jointed forms. Finally its capability for dense coding is investigated and shown n+3 classical bits transmissions by sending only n+1 qubits.