Two-Step Efficient Deterministic Secure Quantum Communication Using Three-Qubit W State

A two-step deterministic secure quantum communication （DSQC） scheme using blocks of three-qubit W state is proposed. In this scheme, the secret messages can be encoded by employing four two-particle unitary operations and directly decoded by utilizing the corresponding measurements in Bell basis or single-particle basis. Comparing with most previous DSQC protocols, the present scheme has a high total efficiency, which comes up to 50%. Apart from this, it has still the advantages of high capacity as each W state can carry two bits of secret information, and high intrinsic efficiency because almost all the instances are useful. Furthermore, the security of this communication can be ensured by the decoy particle checking technique and the two-step transmitting idea.

Preparation of entangledW states based on the cavity QED system

We present a qubit-loss-free(QLF)fusion scheme for generating large-scale atom W states in cavity quantum electrodynamics(QED)system.Compared to the most current fusion schemes which are conditioned on the case where one particle can be extracted from each initial W state to the fusion process,our scheme will access one or two particles from each W state.Based on the atom–cavity-field detuned interaction,three jWin+m+t states can be generated from the jWin,jWim,and jWit states with the help of two auxiliary atoms,and three jWin+m+t+q states can be generated from jWin,jWim,jWit,and a jWiq state with the help of three auxiliary atoms.Comparing the numerical simulations of the resource cost of fusing three small-size W states based on the previous schemes,our fusion scheme seems to be more efficient.This QLF fusion scheme can be generalized to the case of fusing k different or identical particle W states.Furthermore,with no qubit loss,it greatly reduces the number of fusion steps and prepares W states with larger particle numbers.

石榴皮活性物质提取及其W/O/W乳液稳态化包埋研究

石榴是药食同源的水果,在加工过程会产生大量石榴皮渣等副产物。为提高石榴副产物利用率,本文采用不同方法提取石榴皮活性成分,研究其抗氧化活性。采用水包油包水型乳液(W/O/W乳液)对其进行稳态化包埋,研究W/O/W对多酚稳定性及生物利用率的影响。结果表明:相比超高压提取和酶法提取,超声辅助醇提法具有较高的多酚提取率,为25%。石榴皮渣活性提取物对DPPH、羟基自由基清除力、总还原力好于VC;ABTS+清除活性与VC无显著差异;在质量浓度0.4mg/mL以下时,对超氧阴离子清除能力高于VC。W/O/W乳液能提高石榴皮渣活性提取物的储藏稳定性,且可使石榴皮活性物质免受体外胃消化的影响,靶向地在模拟小肠内传递和释放。本研究为石榴皮副产物的深加工提供了理论参考。

Generation of microwave photon perfect W states of three coupled superconducting resonators

We propose an efficient method for the generation of perfect W states on three microwave superconducting resonators,of which the two nearest neighbors are coupled by a symmetric direct current superconducting quantum interference device(dc-SQUID).With suitable external magnetic fluxes applied to the dc-SQUID symmetry loops,on-chip tunable interactions between neighboring resonators can be realized,and different perfect W states can be deterministically created on-demand in one step.Numerical simulations show that high-fidelity target states can be generated and our scheme is robust against imperfect parameter tuning and environment-induced decoherence.The present work may have potential applications for implementing quantum computation and quantum information processing based on microwave photons.

Decoherence suppression for three-qubit W-like state using weak measurement and iteration method

Multi-qubit entanglement states are the key resources for various multipartite quantum communication tasks. For a class of generalized three-qubit quantum entanglement, W-like state, we demonstrate that the weak measurement and the reversal measurement are capable of suppressing the amplitude damping decoherence by reducing the initial damping factor into a smaller equivalent damping factor. Furthermore, we propose an iteration method in the weak measurement and the reversal measurement to enhance the success probability of the total measurements. Finally, we discuss how the number of the iterations influences the overall effect of decoherence suppression, and find that the ＂half iteration＂ method is a better option that has more practical value.

偏滤器部件中W/Cu模块传热的数值模拟分析

利用理论公式和CFX仿真分别对偏滤器部件中平板型W/Cu模块进行稳态热分析,获得了不同热流密度下W/Cu模块的温度场和应力场的变化。理论计算得到的对流传热系数约为52304W·(m^(2)·K)^(‒1),而用CFX仿真分析得到的为35168~52186W·(m^(2)·K)^(‒1)。此外,两种稳态热分析方式得到的W/Cu模块的温度场数值相近;在20MW·m^(‒2)热流密度下,W/Cu模块的温度场、应力场分析结果均超出了对应材料的许用范围,严重影响了偏滤器部件的稳定运行。

Reducible Discord in Generic Three-Qubit Pure W States

Quantum discord is the most prominent of quantum correlations, but it does not have unique generalizations to the multipartite case. W states are especially useful for secure communication. In this paper, we propose that the quantum correlation in generic three-qubit pure W states can be given by the two-qubit discords of these states.

Scheme for entanglement concentration of unknown W class states via linear optics

This paper proposes a scheme for entanglement concentration of unknown triparticle W class states with a certain probability. This protocol is mainly based on the coincidences of single-photon detectors and requires single-photon detectors and linear optical elements. The scheme is feasible within current technology.

Multi-hop teleportation based on W state and EPR pairs

Multi-hop teleportation has significant value due to long-distance delivery of quantum information. Many studies about multi-hop teleportation are based on Bell pairs, partially entangled pairs or W state. The possibility of multi-hop teleportation constituted by partially entangled pairs relates to the number of nodes. The possibility of multi-hop teleportation constituted by double W states is （4/9）~n after n-hop teleportation. In this paper, a multi-hop teleportation scheme based on W state and EPR pairs is presented and proved. The successful possibility of quantum information transmitted hop by hop through intermediate nodes is deduced. The possibility of successful transmission is （2/3）~n after n-hop teleportation.

Controlled Secure Direct Communication Protocol via the Three-Qubit Partially Entangled Set of States

In this paper,we first re-examine the previous protocol of controlled quantum secure direct communication of Zhang et al.’s scheme,which was found insecure under two kinds of attacks,fake entangled particles attack and disentanglement attack.Then,by changing the party of the preparation of cluster states and using unitary operations,we present an improved protocol which can avoid these two kinds of attacks.Moreover,the protocol is proposed using the three-qubit partially entangled set of states.It is more efficient by only using three particles rather than four or even more to transmit one bit secret information.Given our using state is much easier to prepare for multiqubit states and our protocol needs less measurement resource,it makes this protocol more convenient from an applied point of view.

Effect of atmospheric turbulence on entangled orbital angular momentum three-qubit state

The entangled orbital angular momentum（OAM） three photons propagating in Kolmogorov weak turbulence are investigated. Here, the single phase screen model is used to study the entanglement evolution of OAM photons. The results indicate that the entangled OAM three-qubit state with higher OAM modes will be more robust against turbulence.Furthermore, it is found that the entangled OAM three-qubit state has a higher overall transmission for small OAM values.

Measurement-induced nonlocality in the W and Greenberger–Horne–Zeilinger superposition states

Measurement-induced nonlocality（MIN） is a newly defined quantity to measure correlations in bipartite quantum states [Luo S and Fu S 2011 Phys. Rev. Lett. 106 120401]. MIN in the n-qubit W and Greenberger–Horne–Zeilinger（GHZ） superposition states is considered. It is revealed that n = 3 and n ≥ 4 states have very different characteristics,especially the monogamy relation about MIN, and the monogamy equality of MIN is held in all n-qubit W states（n ≥ 3）.

Generation of four-photon W state via cavity QED

This paper proposes an alternative scheme for generating four-photon W state via cavity QED. The scheme bases on the resonant interaction of a A-type three level atom with two bimodal cavities. The detection of atom collapses the cavity to the desired state. Comparing with previous schemes, the advantage of this scheme is that the interaction time can be greatly shortened since it uses the resonant interaction between atom and cavities. Moreover, the proposed scheme is more experimentally feasible than the previous ones.

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.

An optical scheme for conditional generation of W state and photon-added coherent state

We propose a simple scheme to generate an arbitrary photon-added coherent state of a travelling optical field by combining an array of degenerate parametric amplifiers and corresponding single-photon detectors. Particularly, when the single-photon-added coherent state is observed by developing the novel technique of Zavatta et al （2004 Science 306 660）, we can simultar/eously obtain the generalized N-qubit W state.

Remote Preparation of a Two-Particle Entangled State by a Bipartite Entangled State and a Tripartite Entangled W State

We propose a scheme to remotely prepare a general two-particle entangled state by using a bipartite entangled state and a tripartite entangled W state as the quantum channel. Our scheme consists of one sender and two remote receivers. The sender can help either one of the receivers to remotely reconstruct the original state with the assistance of the other receiver＇s single-partlcle orthogona/measurement. We obtain the total success probability and discuss the classical communication cost in our remote state preparation scheme.

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 Dialogue Protocol Using a Class of Three-Photon W States

A theoretical protocol of quantum dialogue is proposed,which uses a class of three-photon W states asquantum channel.After two-step security check,four-bit secret message can be transmitted to each other by transmittingof single photon with the aid of two-bit classical information.

Quantum Secure Direct Communication Using W State

A theoretical scheme of quantum secure direct communication using teleportation is proposed. In the scheme, the sender needs to prepare a class of three-particle W states to use as quantum channel. The two communicators may communicate after they test the security of the quantum channel. The security of the protocol is ensured by quantum entanglement and quantum no-cloning theorem. The receiver can obtain the secret message determinately if the quantum channel is secure.

Quantum Information Splitting of an Arbitrary Three-Qubit State by Using Cluster States and Bell States

A new application of cluster states is investigated for quantum information splitting （QIS） of an arbitrary three-qubit state. In our scheme, a four-qubit cluster state and a Bell state are shared by a sender （Alice）, a controller （Charlie）, and a receiver （Bob）. Both the sender and controller only need to perform Bell-state measurements （BSMs）, the receiver can reconstruct the arbitrary three-qubit state by performing some appropriately unitary transformations on his qubits after he knows the measured results of both the sender and the controller. This QIS scheme is deterministic.