A new theoretical scheme for quantum secure direct communication is proposed, where four-qubit symmetric W state functions as quantum channel. It is shown that two legitimate users can directly transmit the secret mes...A new theoretical scheme for quantum secure direct communication is proposed, where four-qubit symmetric W state functions as quantum channel. It is shown that two legitimate users can directly transmit the secret messages by using Bell-basis measurements and classical communication. The scheme is completely secure if the quantum channel is perfect. Even if the quantum channel is unsecured, it is still possible for two users to perform their secure communication. One bit secret message can be transmitted by sending a bit classical information.展开更多
In this paper, two schemes for teleporting an unknown two-particle entangled state from the sender （Alice） to the receiver （Bob） via a four-particle entangled cluster state are proposed. In these two schemes, the ...In this paper, two schemes for teleporting an unknown two-particle entangled state from the sender （Alice） to the receiver （Bob） via a four-particle entangled cluster state are proposed. In these two schemes, the unknown twoparticle entangled state can be teleported perfectly. The successful probabilities and fidelities of the schemes can reach unity.展开更多
We first provide four new schemes for two-party quantum teleportation of an arbitrary unknown multi-particle state by using three-, four-, and five-particle states as the quantum channel, respectively. The successful ...We first provide four new schemes for two-party quantum teleportation of an arbitrary unknown multi-particle state by using three-, four-, and five-particle states as the quantum channel, respectively. The successful probability and fidelity of the four schemes reach 1. In the first two schemes, the receiver can only apply one of the unitary transformations to reconstruct the original state, making it easier for these two schemes to be directly realized. In the third and fourth schemes, the sender can preform Bell-state measurements instead of multipartite entanglement measurements of the existing similar schemes, which makes real experiments more suitable. It is found that the last three schemes may become tripartite controlled teleportation schemes of teleporting an arbitrary multi-particle state after a simple modification. Finally, we present a new scheme for three-party sharing an arbitrary unknown multi-particle state. In this scheme, the sender first shares three three-particle GHZ states with two agents. After setting up the secure quantum channel, an arbitrary unknown multi-particle state can be perfectly teleported if the sender performs three Bell-state measurements, and either of two receivers operates an appropriate unitary transformation to obtain the original state with the help of other receiver＇s three single-particle measurements. The successful probability and fidelity of this scheme also reach 1. It is demonstrated that this scheme can be generalized easily to the case of sharing an arbitrary unknown multi-particle state among several agents.展开更多
An efficient quantum secure direct communication network protocol with the two-step scheme is proposed by using the Einstein-Podolsky-Rosen （EPR） pair block as the quantum information carrier. The server, say Alice,...An efficient quantum secure direct communication network protocol with the two-step scheme is proposed by using the Einstein-Podolsky-Rosen （EPR） pair block as the quantum information carrier. The server, say Alice, prepares and measures the EPR pairs in the quantum communication and the users perform the four local unitary operations to encode their message. Anyone of the legitimate users can communicate another one on the network securely. Since almost all of the instances in this scheme are useful and each EPR pair can carry two bits of information, the efficiency for qubits and the source capacity both approach the maximal values.展开更多
Two different schemes are presented for quantum teleportation of an arbitrary two-qudit state using a non-maximally four-qudit cluster state as the quantum channel. The first scheme is based on the Bell-basis measurem...Two different schemes are presented for quantum teleportation of an arbitrary two-qudit state using a non-maximally four-qudit cluster state as the quantum channel. The first scheme is based on the Bell-basis measurements and the re-ceiver may probabilistically reconstruct the original state by performing proper transformation on her particles and an auxiliary two-level particle; the second scheme is based on the generalized Bell-basis measurements and the probability of successfully teleporting the unknown state depends on those measurements which are adjusted by Alice. A comparison of the two schemes shows that the latter has a smaller probability than that of the former and contrary to the former, the channel information and auxiliary qubit are not necessary for the receiver in the latter.展开更多
We propose a simultaneous quantum secure direct communication scheme between one party and other three parties via four-particle GHZ states and swapping quantum entanglement. In the scheme, three spatially separated s...We propose a simultaneous quantum secure direct communication scheme between one party and other three parties via four-particle GHZ states and swapping quantum entanglement. In the scheme, three spatially separated senders, Alice, Bob and Charlie, transmit their secret messages to a remote receiver Diana by performing a series of local operations on their respective particles according to the quadripartite stipulation. From Alice, Bob, Charlie and Diana＇s Bell measurement results, Diana can infer the secret messages. Ira perfect quantum channel is used, the secret messages are faithfully transmitted from Alice, Bob and Charlie to Diana via initially shared pairs of four-particle GHZ states without revealing any information to a potential eavesdropper. As there is no transmission of the qubits carrying the secret message in the public channel, it is completely secure for the direct secret communication. This scheme can be considered as a network of communication parties where each party wants to communicate secretly with a central party or server.展开更多
A scheme for teleporting an arbitrary and unknown three-particle state from a sender to either one of two receivers is proposed. The quantum channel is composed of a two-particle non-maximally entangled state and two ...A scheme for teleporting an arbitrary and unknown three-particle state from a sender to either one of two receivers is proposed. The quantum channel is composed of a two-particle non-maximally entangled state and two three-particle non-maximally entangled W states. An arbitrary three-particle state can be perfectly teleported probabilistically if the sender performs three generalized Bell-state measurements and sends to the two receivers the classical result of these measurements, and either one of the two receivers adopts an appropriate unitary transformation conditioned on the suitable measurement outcomes of the other receiver. All kinds of unitary transformations are given in detail.展开更多
Schrodinger＇s thought experiment to prepare a cat in a superposition of both alive and dead states reveals profound consequences of quantum mechanics and has attracted enormous interests. Here we propose a straight- ...Schrodinger＇s thought experiment to prepare a cat in a superposition of both alive and dead states reveals profound consequences of quantum mechanics and has attracted enormous interests. Here we propose a straight- forward method to create quantum superposition states of a living microorganism by putting a small cryopreserved bacterium on top of an electromechanical oscillator. Our proposal is based on recent developments that the center- of-mass oscillation of a 15-pro-diameter aluminum mem- brane has been cooled to its quantum ground state （Teufel et al. in Nature 475：359, 2011）, and entangled with a microwave field （Palomaki et al. in Science 342：710, 2013）. A microorganism with a mass much smaller than the mass of the electromechanical membrane will not signifi- cantly affect the quality factor of the membrane and can be cooled to the quantum ground state together with themembrane. Quantum superposition and teleportation of its center-of-mass motion state can be realized with the help of superconducting microwave circuits. More importantly, the internal states of a microorganism, such as the electron spin of a glycine radical, can be entangled with its center-of- mass motion and teleported to a remote microorganism. Our proposal can be realized with state-of-the-art tech- nologies. The proposed setup is a quantum-limited mag- netic resonance force microscope. Since internal states of an organism contain information, our proposal also pro- vides a scheme for teleporting information or memories between two remote organisms.展开更多
Two kinds of -particle d-dimensional Schmidt-form entangled state teleportation protocols are presented. In the first protocol, the teleportation is achieved by -dimensional Bell-basis measurements, while in the secon...Two kinds of -particle d-dimensional Schmidt-form entangled state teleportation protocols are presented. In the first protocol, the teleportation is achieved by -dimensional Bell-basis measurements, while in the second protocol it is realized by -dimensional GHZ-basis measurement.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 60472017.
文摘A new theoretical scheme for quantum secure direct communication is proposed, where four-qubit symmetric W state functions as quantum channel. It is shown that two legitimate users can directly transmit the secret messages by using Bell-basis measurements and classical communication. The scheme is completely secure if the quantum channel is perfect. Even if the quantum channel is unsecured, it is still possible for two users to perform their secure communication. One bit secret message can be transmitted by sending a bit classical information.
基金The project supported by the National Natural Science Foundation of China under Grant No. 60678022, the Key Program of the Education Department of Anhui Province under Grant Nos. 2006KJ070A, 2006KJ057B and the Talent Foundation of Anhui University
文摘In this paper, two schemes for teleporting an unknown two-particle entangled state from the sender （Alice） to the receiver （Bob） via a four-particle entangled cluster state are proposed. In these two schemes, the unknown twoparticle entangled state can be teleported perfectly. The successful probabilities and fidelities of the schemes can reach unity.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11071178)
文摘We first provide four new schemes for two-party quantum teleportation of an arbitrary unknown multi-particle state by using three-, four-, and five-particle states as the quantum channel, respectively. The successful probability and fidelity of the four schemes reach 1. In the first two schemes, the receiver can only apply one of the unitary transformations to reconstruct the original state, making it easier for these two schemes to be directly realized. In the third and fourth schemes, the sender can preform Bell-state measurements instead of multipartite entanglement measurements of the existing similar schemes, which makes real experiments more suitable. It is found that the last three schemes may become tripartite controlled teleportation schemes of teleporting an arbitrary multi-particle state after a simple modification. Finally, we present a new scheme for three-party sharing an arbitrary unknown multi-particle state. In this scheme, the sender first shares three three-particle GHZ states with two agents. After setting up the secure quantum channel, an arbitrary unknown multi-particle state can be perfectly teleported if the sender performs three Bell-state measurements, and either of two receivers operates an appropriate unitary transformation to obtain the original state with the help of other receiver＇s three single-particle measurements. The successful probability and fidelity of this scheme also reach 1. It is demonstrated that this scheme can be generalized easily to the case of sharing an arbitrary unknown multi-particle state among several agents.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10447106, 10435020, 10254002, A0325401 and 10374010, and Beijing Education Committee under Grant No XK100270454.
文摘An efficient quantum secure direct communication network protocol with the two-step scheme is proposed by using the Einstein-Podolsky-Rosen （EPR） pair block as the quantum information carrier. The server, say Alice, prepares and measures the EPR pairs in the quantum communication and the users perform the four local unitary operations to encode their message. Anyone of the legitimate users can communicate another one on the network securely. Since almost all of the instances in this scheme are useful and each EPR pair can carry two bits of information, the efficiency for qubits and the source capacity both approach the maximal values.
基金Supported by the Natural Science Research Project of Shanxi Province (Grant No. 2004A15)
文摘Two different schemes are presented for quantum teleportation of an arbitrary two-qudit state using a non-maximally four-qudit cluster state as the quantum channel. The first scheme is based on the Bell-basis measurements and the re-ceiver may probabilistically reconstruct the original state by performing proper transformation on her particles and an auxiliary two-level particle; the second scheme is based on the generalized Bell-basis measurements and the probability of successfully teleporting the unknown state depends on those measurements which are adjusted by Alice. A comparison of the two schemes shows that the latter has a smaller probability than that of the former and contrary to the former, the channel information and auxiliary qubit are not necessary for the receiver in the latter.
基金Supported by the Natural Science Foundation of Hebei Province under Grant Nos A2004000141 and A2005000140, and the Natural Science Foundation of Hebei Normal University.
文摘We propose a simultaneous quantum secure direct communication scheme between one party and other three parties via four-particle GHZ states and swapping quantum entanglement. In the scheme, three spatially separated senders, Alice, Bob and Charlie, transmit their secret messages to a remote receiver Diana by performing a series of local operations on their respective particles according to the quadripartite stipulation. From Alice, Bob, Charlie and Diana＇s Bell measurement results, Diana can infer the secret messages. Ira perfect quantum channel is used, the secret messages are faithfully transmitted from Alice, Bob and Charlie to Diana via initially shared pairs of four-particle GHZ states without revealing any information to a potential eavesdropper. As there is no transmission of the qubits carrying the secret message in the public channel, it is completely secure for the direct secret communication. This scheme can be considered as a network of communication parties where each party wants to communicate secretly with a central party or server.
文摘A scheme for teleporting an arbitrary and unknown three-particle state from a sender to either one of two receivers is proposed. The quantum channel is composed of a two-particle non-maximally entangled state and two three-particle non-maximally entangled W states. An arbitrary three-particle state can be perfectly teleported probabilistically if the sender performs three generalized Bell-state measurements and sends to the two receivers the classical result of these measurements, and either one of the two receivers adopts an appropriate unitary transformation conditioned on the suitable measurement outcomes of the other receiver. All kinds of unitary transformations are given in detail.
基金the support from Purdue University and helpful discussions with G.Csathy,F.Robicheaux, C.Greene,and V.ShalaevZQY is funded by the National Basic Research Program of China (2011CBA00300 and 2011CBA00302)the National Natural Science Foundation of China (11105136, 11474177 and 61435007)
文摘Schrodinger＇s thought experiment to prepare a cat in a superposition of both alive and dead states reveals profound consequences of quantum mechanics and has attracted enormous interests. Here we propose a straight- forward method to create quantum superposition states of a living microorganism by putting a small cryopreserved bacterium on top of an electromechanical oscillator. Our proposal is based on recent developments that the center- of-mass oscillation of a 15-pro-diameter aluminum mem- brane has been cooled to its quantum ground state （Teufel et al. in Nature 475：359, 2011）, and entangled with a microwave field （Palomaki et al. in Science 342：710, 2013）. A microorganism with a mass much smaller than the mass of the electromechanical membrane will not signifi- cantly affect the quality factor of the membrane and can be cooled to the quantum ground state together with themembrane. Quantum superposition and teleportation of its center-of-mass motion state can be realized with the help of superconducting microwave circuits. More importantly, the internal states of a microorganism, such as the electron spin of a glycine radical, can be entangled with its center-of- mass motion and teleported to a remote microorganism. Our proposal can be realized with state-of-the-art tech- nologies. The proposed setup is a quantum-limited mag- netic resonance force microscope. Since internal states of an organism contain information, our proposal also pro- vides a scheme for teleporting information or memories between two remote organisms.
文摘Two kinds of -particle d-dimensional Schmidt-form entangled state teleportation protocols are presented. In the first protocol, the teleportation is achieved by -dimensional Bell-basis measurements, while in the second protocol it is realized by -dimensional GHZ-basis measurement.
