Two-particle Entangled State Research Articles

Two Quantum Proxy Blind Signature Schemes Based on Controlled Quantum Teleportation

We present a scheme for teleporting an unknown, two-particle entangled state with a message from a sender (Alice) to a receiver (Bob) via a six-particle entangled channel. We also present another scheme for teleporting an unknown one-particle entangled state with a message transmitted in a two-way form between the same sender and receiver via a five-qubit cluster state. One-way hash functions, Bell-state measurements, and unitary operations are adopted in these two schemes. Our schemes use the physical characteristics of quantum mechanics to implement delegation, signature, and verification processes. Moreover, a quantum key distribution protocol and a one-time pad are adopted in these schemes.

Probabilities and Certainties Within a Causally Symmetric Model

This paper is concerned with the causally symmetric version of the familiar de Broglie–Bohm interpretation, this version allowing the spacelike nonlocality and the configuration space ontology of the original model to be avoided via the addition of retrocausality. Two different features of this alternative formulation are considered here. With regard to probabilities, it is shown that the model provides a derivation of the Born rule identical to that in Bohm’s original formulation. This derivation holds just as well for a many-particle, entangled state as for a single particle. With regard to “certainties”, the description of a particle’s spin is examined within the model and it is seen that a statistical description is no longer necessary once final boundary conditions are specified in addition to the usual initial state, with the particle then possessing a definite (but hidden) value for every spin component at intermediate times. These values are consistent with being the components of a single, underlying spin vector. The case of a two-particle entangled spin state is also examined and it is found that, due to the retrocausal aspect, each particle possesses its own definite spin during the entanglement, independent of the other particle. In formulating this picture, it is demonstrated how such a realistic model can preserve Lorentz invariance in the face of Bell’s theorem and avoid the need for a preferred reference frame.

A rational quantum state sharing protocol with semi-off-line dealer

A rational quantum state sharing protocol with the semi-off-line dealer is proposed. Firstly, the dealer Alice shares an arbitrary two-particle entangled state with the players by Einstein–Podolsky–Rosen (EPR) pairs and Greenberger–Horne–Zeilinger (GHZ) states. The EPR pairs are prepared by Charlie instead of the dealer, reducing the workload of the dealer. Secondly, all players have the same probability of reconstructing the quantum state, guaranteeing the fairness of the protocol. In addition, the dealer is semi-off-line, which considerably reduces the information exchanging between the dealer and the players. Finally, our protocol achieves security, fairness, correctness, and strict Nash equilibrium.

Quantum Secure Multiparty Summation Based on the Phase Shifting Operation of d-Level Quantum System and its Application

A quantum secure multiparty summation protocol is constructed based on the phase shifting operation of d-level quantum system which utilizes the integer-by-integer technique to calculate the modulo d addition. The semi-honest third party prepares d-level two-particle entangled states and transmits the particle sequence composed by all second particles to n secrecy owners. n secrecy owners in turn encode their respective secrecy on this particle sequence through the phase shifting operation. Detailed security analysis turns out that both the outside attack and the participant attack are ineffective towards this protocol. Compared with the quantum secure summation protocols with bit-by-bit calculations, its calculation efficiency is higher; and compared with the protocols with smaller modulo, its applications are more extensive. Especailly, this protocol has extensive applications in the realm of quantum secure multiparty computation, such as quantum multiparty private comparison, quantum multiparty anonymous ranking, quantum multiparty anonymous voting, quantum multiparty key agreement, etc.

Experimental realization of quantum teleportation of an arbitrary two-qubit state using a four-qubit cluster state

Quantum teleportation is extensively used in quantum communication where a sender sends a information to a receiver at a large distance through a quantum entangled channel. Li and Cao (Commun Theor Phys 47(3):464, 2007) proposed a theoretical scheme for teleportation of a two-particle entangled state via cluster state. Here, we present the above scheme of teleportation for an arbitrary state by using a four-qubit cluster state. We demonstrate the scheme on the IBM quantum computer by designing appropriate quantum circuits using single-qubit and two-qubit quantum gates. We collect the experimental results with good fidelity revealing the teleportation of an arbitrary two-qubit state using a four-qubit cluster state.

Controlled quantum dialogue scheme based on different unspecific two-particle entangled state

In this paper, a controlled quantum dialogue (CQD) scheme based on different unspecific two-particle entangled state is proposed, in which legitimate users can exchange their secret messages according to unitary operations they chose and measurement results published by Charlie, realizing transmitting unspecific secrets by using unspecific entangled state. We insert decoy particles twice and get rid of useless secret messages carried by F particles to ensure security of the whole communication system, realizing the three-times channel detection. Compared to previous CQD protocols, the proposed scheme is proved to stand attack from third-party controller, and it is very secure.

A Proxy Blind Signature Scheme of Quantum Information Transmission in Two-Particle State

A new proxy blind signature scheme based on controlled quantum teleportation is presented in this paper. We present a scheme for teleporting an unknown two-particle entangled state with message from a sender (Alice) to a receiver (David) via a genuine six-qubit entangled state. In this scheme, we introduce a trusted third party to enhance security and effectively resist forgery attacks. One-way hash faction, Von-Neumann measurement and unitary operation are adapted in this scheme. Our scheme uses the physical characteristics of quantum mechanics to implement delegation, signature and verification. Moreover, quantum key distribution (QKD) protocol and one-time pad are adapted in this scheme.

A novel semi-quantum secret sharing scheme using entangled states

Semi-quantum secret sharing (SQSS) can transmit secret messages. Most existing SQSS protocols can only use one or two specific entangled states to share unspecific or specific classical message. In this paper, we propose a novel SQSS protocol using N different unspecific two-particle entangled state [Formula: see text], [Formula: see text] to share unspecific message, in which quantum Alice can transmit classical messages with classical Bob and Charlie. In addition, we have proved that the protocol can strongly resist some forms of eavesdropping.

Unknown Two Particles Teleportation Using a Special Two-Particle Quantum Channel

In this paper, two schemes of teleporting two particles are proposed. In first scheme, an auxiliary particle is introduced to transfer a two-particle state with special coefficients. The sender adopts Bell bases measurement and Von Neumann measurement, then the receiver obtain the state through appropriate unitary transformation. In second scheme, two special two-particle entangled states are chosen as quantum channel. The sender takes Bell bases measurement twice, and transfers the results to the receiver by classical channel, then the receiver gets the transmitted state through unitary transformation.

Three-Party Simultaneous Quantum Secure Communication Based on Closed Transmission Loops

A kind of novel three-party quantum secure direct communication protocol is proposed with the correlation of two-particle entangled state. In this scheme the qubit transmission forms a closed loop and every one of the three participants is both a receiver and a sender of particle sequences in the bidirectional quantum channels. Each party implements the corresponding unitary operations according to its secret bit value over the quantum channels and then extracts the other two parties’ unitary operations by performing Bell measurements on the encoded particles. Thus they can obtain the secret information simultaneously. Finally, the security analysis shows that the present three-party scheme is a secure protocol.

Quantum Teleportation of the Two-Qubit Entangled State by Use of Four-Qubit Entangled State

In this article, a scheme for quantum teleportation of a two-qubit entangled state using four-qubit cluster state is discussed by use of cavity quantum electrodynamics (QED) involving the interaction of the atoms with the cavity. In this protocol, by using a one-dimensional maximally four-qubit cluster state as quantum channel, quantum information of an unknown state of two two-level particles is faithfully transmitted from a sender (Alice) to a remote receiver (Bob). According to the results measured by the Bob, as it is shown, the unknown two-particle entangled state can be teleported perfectly, and the successful possibilities and fidelities of the scheme can reach 1.0.

Probabilistic Controlled Teleportation of Two-Particle Entangled State via the Optimal Quantum State

Via a non-maximally entangled state as the optimal quantum channel, we discuss the probabilistic controlled teleportation of two-particle anti-correlation entangled state. We first defines four-particle special “anti-correlation GHZ state” as the quantum channel, then the sender and the controller do a series of measurements. According to their measurements, the receiver perform an appropriate unitary transformation and measurement on the auxiliary particle, then he can get the quantum state he wants. Moreover, We present the successful probability of the above controlled teleportation.

THE CONCENTRATION PROTOCOL OF A TWO-PARTICLE NON-MAXIMALLY ENTANGLED STATE AMONG THREE CAVITIES

We propose a scheme for concentrating an arbitrary two-particle non-maximally entangled state into a maximally entangled state assisted with three cavities. The scheme involves two interaction–detection cycles and resonant interaction between atom and cavity mode. With the help of the atom trapped in the cavity, the concentration of a two-particle non-maximally entangled state trapped in separate cavities can be realized with a certain probability according to the results of photon detectors. The important feature of our scheme is that we can realize the concentration of an arbitrary two-atom non-maximally entangled state and we do not perform Bell-state measurements.

Efficient quantum secret sharing scheme with two-particle entangled states

This paper proposes a protocol for multi-party quantum secret sharing utilizing four non-orthogonal two-particle entangled states following some ideas in the schemes proposed by Liu et al. (2006 Chin. Phys. Lett. 23 3148) and Zhang et al. (2009 Chin. Phys. B 18 2149) respectively. The theoretical efficiency for qubits of the new protocol is improved from 50% to approaching 100%. All the entangled states can be used for generating the private key except those used for the eavesdropping check. The validity of a probable attack called opaque cheat attack to this kind of protocols is considered in the paper for the first time.

FAITHFUL CLONE OF AN UNKNOWN TWO-PARTICLE ENTANGLED STATE WITH ASSISTANCE

We propose a deterministic and faithful scheme for realizing the assisted clone of an unknown two-particle entangled state. The first stage of the protocol requires teleportation via maximal entanglement. In the second stage, a novel set of mutually orthogonal basis vectors is constructed. With the assistance of the preparer through a two-particle projective measurement under this basis, a perfect copy of an original state can be produced. Compared with the previous protocols which produce the unknown state and its orthogonal complement state at the site of the sender, our scheme generates the unknown state deterministically. On the other hand, we put forward another assisted clone scheme via nonmaximal entanglement as the quantum channel. A faithful copy of the unknown state can be obtained with a certain probability.

Deterministic and exact entanglement teleportation via the W state

Utilizing a three-particle W state, we come up with a protocol for the teleportation of an unknown two-particle entangled state. It is shown that the teleportation can be deterministically and exactly realized. Moreover, two-particle entanglement teleportation is generalized to a system consisting of many particles via a three-particle W state and a multi-particle W state, respectively. All unitary transformations performed by the receiver are given in a concise formula.

Quantum secret sharing between m-party and n-party with six states

We propose a quantum secret sharing scheme between $m$-party and $n$-party using three conjugate bases, i.e. six states. A sequence of single photons, each of which is prepared in one of the six states, is used directly to encode classical information in the quantum secret sharing process. In this scheme, each of all $m$ members in group 1 choose randomly their own secret key individually and independently, and then directly encode their respective secret information on the states of single photons via unitary operations, then the last one (the $m$th member of group 1) sends $1/n$ of the resulting qubits to each of group 2. By measuring their respective qubits, all members in group 2 share the secret information shared by all members in group 1. The secret message shared by group 1 and group 2 in such a way that neither subset of each group nor the union of a subset of group 1 and a subset of group 2 can extract the secret message, but each whole group (all the members of each group) can. The scheme is asymptotically 100% in efficiency. It makes the Trojan horse attack with a multi-photon signal, the fake-signal attack with EPR pairs, the attack with single photons, and the attack with invisible photons to be nullification. We show that it is secure and has an advantage over the one based on two conjugate bases. We also give the upper bounds of the average success probabilities for dishonest agent eavesdropping encryption using the fake-signal attack with any two-particle entangled states. This protocol is feasible with present-day technique.

SCHEME FOR IMPLEMENTING ASSISTED CLONING OF AN UNKNOWN TWO-PARTICLE ENTANGLED STATE VIA CLUSTER STATE

We present a scheme that can realize quantum cloning of an unknown two-particle entangled state and its orthogonal-complement state with assistance offered by a state preparer, via entangled cluster state as quantum channel. The first stage of the scheme requires usual teleportation via a maximally four-particle entangled cluster state as quantum channel. In the second stage of the scheme, with the assistance (through a two-particle projective measurement) of the preparer, the perfect copies and complement copies of an unknown two-particle entangled state can be obtained. We also put forward a scheme for the teleportation by using nonmaximally entangled quantum channel. The clones and complement clones of unknown state can be produced with certain probability in the latter scheme.

PROBABILISTIC REMOTELY PREPARING AN ARBITRARY TWO-PARTICLE ENTANGLED STATE VIA POSITIVE OPERATOR-VALUED MEASURE

By means of the method of the positive operator-valued measure, two schemes to remotely prepare an arbitrary two-particle entangled state were presented. The first scheme uses a one-dimensional four-particle non-maximally entangled cluster state while the second one uses two partially entangled two-particle states as the quantum channel. For both schemes, if Alice performs two-particle projective measurements and Bob adopts positive operator-valued measure, the remote state preparation can be successfully realized with certain probability. The success probability of the remote state preparation and classical communication cost are calculated. It is shown that Bob can obtain the unknown state with probability 1/4 for maximally entangled state. However, for four kinds of special states, the success probability of preparation can be enhanced to unity.

Scheme for Cloning an Unknown Entangled State with Assistance via Non-maximally Entangled Cluster States

We propose a scheme for cloning unknown two-particle entangled state and its orthogonal complement state with assistance from a state preparer. Two stages were included in this scheme. The first stage requires usual teleportation by using a one-dimensional non-maximally four-particle cluster state as quantum channel, after Alice’s (the state sender) Bell measurement, Bob (the state receiver) can get the original state with certain probability. In the second stage, after having received Victor’s (the state preparer) classical message, the perfect copies and complement copies of an unknown state can be produced in Alice’s place, the probability of Alice to get the original state or its orthogonal complement state are calculated. Assisted cloning of an arbitrary unknown two-particle entangled state is discussed in the latter scheme.