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.     

Quantum superdense coding based on hyperentanglement

We present a scheme for quantum superdense coding with hyperentanglement,in which the sender can transfer four bits of classical information by sending only one photon.The important device in the scheme is the hyperentangled Bell-state analyzer in both polarization and frequency degrees of freedom,which is also constructed in the paper by using a quantum nondemolition detector assisted by cross-Kerr nonlinearity.Our scheme can transfer more information with less resources than the existing schemes and is nearly deterministic and nondestructive.     

Simple experimental scheme of teleporting a two-qubit state via linear optical elements

We propose a simple experimental scheme in which an unknown two-qubit state is faithfully and deterministically teleported from Alice to Bob. The scheme is constructed with four photons from parametric down conversion, linear optical elements, and conventional photon detectors, all of which are available in current technology. It is shown that the probability of successful teleportation ideally reaches 100% based on single-photon two-qubit-assisted Bell-state measurement, which can distinguish all four Bell-states simultaneously via conventional photon detectors. By generalizing the scheme, the teleportation of an unknown multi-qubit system can also be realized.     

Complete <Emphasis Type="Italic">N</Emphasis>-Photon Greenberger-Horne-Zeilinger State Analysis Using Hyperentanglement

We present a scheme for N-photon Greenberger-Horne-Zeilinger (GHZ) state analysis using hyperentanglement in polarization and time-bin degrees of freedom. The scheme only needs linear optics elements and single-photon detectors, which is feasible with current technology. The set of 2 ^N mutual orthogonal states can be unambiguously distinguished and the protocol is expected to find useful applications in quantum information processing.     

Efficient faithful qubit transmission with frequency degree of freedom

We propose an efficient faithful polarization-state transmission scheme by utilizing frequency degree of freedom besides polarization and an additional qubit prepared in a fixed polarization. An arbitrary single-photon polarization state is protected against the collective noise probabilistically. With the help of frequency beam splitter and frequency shifter, the success probability of our faithful qubit transmission scheme with frequency degree of freedom can be 1/2 in principle.     

Deterministic Tripartite Entanglement Distributions of the W State over Collective-Noise Channels

A deterministic entanglement distribution protocol (EDP) is proposed in principle for transmitting a maximally entangled W state over collective-noise channels. Using this EDP, a W state can be reconstructed directly from a three-photon entangled state in the frequency degree of freedom prepared among three remote participants due to the fact that it suffers little from the channel noise. In essence, it is a entanglement transformation between different degrees of freedom in three-photon entangled system. This EDP adopts the cross-Kerr nonlinearity media to complete the task of the single-photon detections, which can increase the efficiency of entanglement distribution since it does not require the sophisticated single-photon detectors for the usual measurements and the retained photons can be still held solely by three respective participants after entanglement distillation.     

Quantum State Sharing of an Arbitrary Three-Atom State by Using Five-Atom Cluster State in Cavity QED

We present a scheme for implementing the deterministic quantum state sharing of an arbitrary three-atom state by using a five-atom cluster state and a Bell-state in cavity QED. In the scheme, it does not involve Bell-state measurement and only needs to perform the single-atom measurements. Our scheme is not sensitive to both the cavity decay and the atom radiation, which is of importance in view of decoherence.     

High-Capacity Three-Party Quantum Secret Sharing with Single Photons in Both the Polarization and the Spatial-Mode Degrees of Freedom

We present a high-capacity three-party quantum secret sharing (QSS) protocol with a sequence of single photons in both the polarization and the spatial-mode degrees of freedom. By inserting the boss Alice into the middle position between the two agents Bob and Charlie, our QSS protocol is secure in theory. The boss Alice chooses some unitary operations to encode her information on the single photons. It is interesting to point out the fact that Alice does not change the bases of the single photons which are used to carry the useful information about the private key, which improves its success probability for obtaining a private key. Compared with the QSS protocol by Zhou et al. (Chin. Phys. Lett. 24, 2181 (2007)), our QSS protocol has a higher capacity without increasing the difficulty of its implementation in experiment as each correlated photon can carry two bits of useful information. Compared with those QSS protocols based on entangled photon pairs and Bell-state measurements, our QSS protocol is more feasible as it does not require the complete Bell-state analysis which is not easy with linear optics. We give out the setup for the implementation of our QSS protocol with linear optical elements.     

Quantum Information Splitting of an Arbitrary Three-Atom State in Cavity Quantum Electrodynamics

A cavity quantum electrodynamics scheme for implementing the deterministic quantum information splitting of an arbitrary three-atom state is proposed. In the scheme, a genuine five-atom entangled state and a Bell-state can be used as the quantum channel, which does not involve Bell-state measurement and only needs to perform the single-atom measurements. Our scheme is insensitive to both the cavity decay and the atom radiation, and considered here is secure against certain eavesdropping attacks.     

Quantum State Sharing by Using an Eight-Atom Composite W-Bell State in Cavity QED

We demonstrate that an eight-atom composite W-Bell state can be used to realize the deterministic quantum state sharing of an arbitrary two-atom state in cavity QED. In the scheme, it does not involve Bell-state measurement and only needs to perform the single-atom measurements. Our scheme is not sensitive to both the cavity decay and the atom radiation, which is of importance in view of decoherence.     

High-Capacity Quantum Secure Direct Communication with Single Photons in Both Polarization and Spatial-Mode Degrees of Freedom

We present a high-capacity quantum secure direct communication (QSDC) protocol with single photons in both the polarization and the spatial-mode degrees of freedom. With a single photon traveling forth and back from the receiver to the sender, it can carry 2 bits of information as the sender can encode his message on both the polarization states and the spatial-mode states of single photons independently. Moreover, our QSDC protocol is feasible as the preparation and the measurement of a single-photon quantum state in both the polarization and the spatial-mode degrees of freedom is not difficult with current technology.     

Quantum information splitting of an arbitrary three-qubit state via the cavity input–output process

We propose a realizable quantum information splitting (QIS) scheme for an arbitrary three-qubit state via the cavity input–output process. In our scheme, a four-qubit cluster state and a three-qubit Greenberger–Horne–Zeilinge (GHZ) state are used as quantum channel. The sender and controller only need to perform Bell-state measurements and a single-qubit measurement, respectively. The receiver can reconstruct the arbitrary three-qubit state by classical communication and local operations. Compared with the scheme in Nie et al. [Optics Communications 284 (2011) 1457], the quantum resources and classical information in our scheme are decreased by 5 qubits and 1 bit, respectively. Moreover, we replace the W-state category measurement in the former with Bell-state measurements and a single-qubit measurement, which is more simple and feasible in experiment.     

Quantum message exchange based on entanglement and Bell-state measurements

We propose a scheme by which two parties can secretly and simultaneously exchange messages. The scheme requires the two parties to share entanglement and both to perform Bell-state measurements. Only two out of the four Bell states are required to be distinguished in the Bell-state measurements, and thus the scheme is experimentally feasible using only linear optical means. Generalizations of the scheme to high-dimensional systems and to multipartite entanglement are considered. We show also that the proposed scheme works even if the two parties do not possess shared reference frames.     

Probabilistic teleportation of unknown atomic states using non-maximally entangled states without Bell-state measurement

We propose a physical scheme for teleporting an unknown atomic state in cavity QED. Our scheme does not involve the Bell-state measurement. The most distinctive advantage of our scheme is that teleportation and distillation procedure can be realized simultaneously. In addition, the current scheme is insensitive to the cavity decay.     

Nondestructive and complete Bell-state analysis for atomic qubit systems

This paper realizes a nondestructive and complete Bell-state analysis for atomic qubit systems by a designed nondestructive and complete Bell-state analyser. In the scheme, Bell states are completely discriminated by two bits of classical informations which comes from the locality single atom detection on two auxiliary atoms, during which the Bell states are not affected. The needed devices are well within the bounds of current technology, and then the scheme is experimentally feasible.     

Generation of Maximally Entangled States for Many Two-Level Atoms in a Thermal Cavity

We propose a scheme for generating maximally entangled states for two or more two-level atoms in a thermal cavity. The cavity frequency is large-detuned from the atomic transition frequency, so the Hamiltonian can be expressed as an effective form. The photon-number-dependent parts in the effective Hamiltonian are cancelled with the assistance of a strong classical field, thus the scheme is insensitive to both the cavity decay and the thermal field. The scheme can be used to generate multi-atom Bell-state and Greenberger-Horne-Zeiliner （GHZ） state.     

Remote preparation for single-photon state in two degrees of freedom with hyper-entangled states

Remote state preparation (RSP) provides a useful way of transferring quantum information between two distant nodes based on the previously shared entanglement. In this paper, we study RSP of an arbitrary single-photon state in two degrees of freedom (DoFs). Using hyper-entanglement as a shared resource, our first goal is to remotely prepare the single-photon state in polarization and frequency DoFs and the second one is to reconstruct the single-photon state in polarization and time-bin DoFs. In the RSP process, the sender will rotate the quantum state in each DoF of the photon according to the knowledge of the state to be communicated. By performing a projective measurement on the polarization of the sender’s photon, the original single-photon state in two DoFs can be remotely reconstructed at the receiver’s quantum systems. This work demonstrates a novel capability for longdistance quantum communication.     

Quantum error rejection for faithful quantum communication over noise channels

Quantum state transmission is a prerequisite for various quantum communication networks. The channel noise inevitably introduces distortion of quantum states passing through either a free-space channel or a fibre channel, which leads to errors or decreases the security of a practical quantum communication network. Quantum error rejection is a useful technology to faithfully transmit quantum states over large-scale quantum channels. It provides the communication parties with an uncorrupted quantum state by rejecting error states. Usually, additional photons or degrees of freedom are required to overcome the adverse effects of channel noise. As quantum error rejection method consumes less quantum resource than other anti-noise methods, it is more convenient to perform error-rejection quantum state transmission with current technology. In this review, several typical quantum errorrejection schemes for single-photon state transmission are introduced in brief and some error-rejection schemes for entanglement distribution are also briefly presented.     

Tripartite Probabilistic and Controlled Teleportation of an Arbitrary Single-Qubit State via One-Dimensional Four-Qubit Cluster-Type State

A tripartite scheme for probabilistically teleporting an arbitrary single-qubit state with one-dimensional four-qubit cluster-type state as the quantum channel is proposed. In the scheme, both of the sender and the controller perform a Bell-state measurement (BSM) on their respective qubit pair and announce the measurement results via classical communication. With the help of the sender and the controller, the receiver can reconstruct the original state with a certain probability by introducing an auxiliary qubit and making appropriate unitary operations and measurement. In addition, the total success probability and classical message cost of the present scheme are also worked out.     

基于六粒子纠缠态和Bell态测量的量子信息分离

通过介绍六粒子纠缠态的新应用研究,提出了一个二粒子任意态的信息分离方案.在这个方案中,发送者Alice、控制者Charlie和接受者Bob共享一个六粒子纠缠态,发送者先执行两次Bell基测量;然后控制者执行一次Bell基测量;最后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,从而能够重建要发送的...