We propose a practical entanglement concentration protocol (ECP) for a hybrid entangled state using quantum dots and a microcavity coupled system. A hybrid less-entangled state can he concentrated to a most-entangle...We propose a practical entanglement concentration protocol (ECP) for a hybrid entangled state using quantum dots and a microcavity coupled system. A hybrid less-entangled state can he concentrated to a most-entangled state with a certain probability using only one ancillary single photon. Moreover, using this protocol, we can also concentrate an arbitrary three-particle less-entangled W state using two ancillary photons and classical communication. The proposed protocols provide us with a useful method to concentrate less-entangled states, which can he implemented with current technology.展开更多
We investigate the generation of entanglement of coherent excitonic states in coupled quantum dots placedin a cavity by meaning of the state preparation fidelity [Nature (London) 404 (2002) 256;Phys.Rev.A 65 (2002) 01...We investigate the generation of entanglement of coherent excitonic states in coupled quantum dots placedin a cavity by meaning of the state preparation fidelity [Nature (London) 404 (2002) 256;Phys.Rev.A 65 (2002) 012107;J.Uffink,Phys.Rev.Lett.88 (2002) 230406.] The effect of the number of exeitons and the coherent intensity |α| of thecavity field on the entanglement is also studied.展开更多
We discuss a quantum remote state preparation protocol by which two parties, Alice and Candy, prepare a single-qubit and a two-qubit state, respectively, at the site of the receiver Bob. The single-qubit state is know...We discuss a quantum remote state preparation protocol by which two parties, Alice and Candy, prepare a single-qubit and a two-qubit state, respectively, at the site of the receiver Bob. The single-qubit state is known to Alice while the two-qubit state which is a non-maximally entangled Bell state is known to Candy. The three parties are connected through a single entangled state which acts as a quantum channel. We first describe the protocol in the ideal case when the entangled channel under use is in a pure state. After that, we consider the effect of amplitude damping(AD) noise on the quantum channel and describe the protocol executed through the noisy channel. The decrement of the fidelity is shown to occur with the increment in the noise parameter. This is shown by numerical computation in specific examples of the states to be created. Finally, we show that it is possible to maintain the label of fidelity to some extent and hence to decrease the effect of noise by the application of weak and reversal measurements. We also present a scheme for the generation of the five-qubit entangled resource which we require as a quantum channel. The generation scheme is run on the IBMQ platform.展开更多
<Abstract>Recently,several similarprotocols [J.Opt.B 4 (2002) 380;Phys.Lett.A 316 (2003) 159;Phys.Lett.A 355 (2006) 285;Phys.Lett.A 336 (2005) 317] for remotely preparing a class of multi-qubit states (i.e,α|O....<Abstract>Recently,several similarprotocols [J.Opt.B 4 (2002) 380;Phys.Lett.A 316 (2003) 159;Phys.Lett.A 355 (2006) 285;Phys.Lett.A 336 (2005) 317] for remotely preparing a class of multi-qubit states (i.e,α|O...O〉 + β|1...1〉) were proposed,respectively.In this paper,by applying the controlled-not (CNOT) gate,a new simple protocol is proposed for remotely preparing such class of states.Compared to the previous protocols,both classical communication cost and required quantum entanglement in our protocol are remarkably reduced.Moreover,the difficulty of identifying some quantum states in our protocol is also degraded.Hence our protocol is more economical and feasible.展开更多
We have numerically calculated the thermal entanglement of a two-qubit system at low temperatures in a isotropic Ising chain under an inhomogeneous magnetic field. It is shown that in the homogeneous magnetic field, t...We have numerically calculated the thermal entanglement of a two-qubit system at low temperatures in a isotropic Ising chain under an inhomogeneous magnetic field. It is shown that in the homogeneous magnetic field, the two- qubit system has entangled states. It is concluded that the presence of the inhomogeneity in the magnetic field plays an effective role on the entangled states. Finally, it is suggested that the inhomogeneity in the magnetic field can be used to create two separated entangled formations in a two-qubit system.展开更多
It is a simple introduction to quantum entanglement and quantum operations.The authors focus on some applications of quantum entanglement and relations between two-qubit entangled states and unitary operations.It incl...It is a simple introduction to quantum entanglement and quantum operations.The authors focus on some applications of quantum entanglement and relations between two-qubit entangled states and unitary operations.It includes remote state preparation by using any pure entangled states,nonlocal operation implementation using entangled states,entanglement capacity of two-qubit gates and two-qubit gates construction.展开更多
Two schemes are proposed to realize the controlled remote preparation of an arbitrary four-qubit cluster-type state via a partially entangled channel. We construct ingenious measurement bases at the sender’s and the ...Two schemes are proposed to realize the controlled remote preparation of an arbitrary four-qubit cluster-type state via a partially entangled channel. We construct ingenious measurement bases at the sender’s and the controller’s locations, which play a decisive role in the proposed schemes. The success probabilities can reach 50% and 100%, respectively. Compared with the previous proposals, the success probabilities are independent of the coefficients of the entangled channel.展开更多
Although the multi-level structure of superconducting qubits may result in calculation errors, it can be rationally used to effectively improve the speed of gate operations. Utilizing a current-biased Josephson juncti...Although the multi-level structure of superconducting qubits may result in calculation errors, it can be rationally used to effectively improve the speed of gate operations. Utilizing a current-biased Josephson junction (A-type rf-SQUID) as a tunable coupler for superconducting transmission line resonators (TLRs), under the large detuning condition, we demonstrate the controllable generation of entangled coherent states in circuit quantum electrodynamics (circuit QED). The coupling between the TLRs and the qubit can be effectively regulated by an external bias current or coupling capacitor. Further investigations indicate that the maximum entangled state can be obtained through measuring the excited state of the superconducting qubits. Then, the influence of the TLR [tecay on the prepared entangled states is analyzed.展开更多
We present two schemes for realizing the remote preparation of a Greenberger-Horne-Zeilinger (GHZ) state. The first scheme is to remotely prepare a general N-particle GHZ state with two steps. One is to prepare a qu...We present two schemes for realizing the remote preparation of a Greenberger-Horne-Zeilinger (GHZ) state. The first scheme is to remotely prepare a general N-particle GHZ state with two steps. One is to prepare a qubit state by using finite classical bits from sender to receiver via a two-particle entangled state, and the other is that the receiver introduces N - 1 additional particles and performs N - 1 controlled-not (C-Not) operations. The second scheme is to remotely prepare an N-atom GHZ state via a two-atom entangled state in cavity quantum electrodynamics (QED). The two schemes require only a two-particle entangled state used as a quantum channel, so we reduce the requirement for entanglement.展开更多
In this paper, two novel schemes for deterministic joint remote state preparation(JRSP) of arbitrary single- and twoqubit states are proposed. A set of ingenious four-particle partially entangled states are construc...In this paper, two novel schemes for deterministic joint remote state preparation(JRSP) of arbitrary single- and twoqubit states are proposed. A set of ingenious four-particle partially entangled states are constructed to serve as the quantum channels. In our schemes, two senders and one receiver are involved. Participants collaborate with each other and perform projective measurements on their own particles under an elaborate measurement basis. Based on their measurement results,the receiver can reestablish the target state by means of appropriate local unitary operations deterministically. Unit success probability can be achieved independent of the channel's entanglement degree.展开更多
Due to the unavoidable interaction between the quantum channel and its ambient environment,it is difficult to generate and maintain the maximally entanglement.Thus,the research on multiparty information transmission v...Due to the unavoidable interaction between the quantum channel and its ambient environment,it is difficult to generate and maintain the maximally entanglement.Thus,the research on multiparty information transmission via non-maximally entangled channels is of academic value and general application.Here,we utilize the non-maximally entangled channels to implement two multiparty remote state preparation schemes for transmitting different quantum information from one sender to two receivers synchronously.The first scheme is adopted to transmit two different four-qubit cluster-type entangled states to two receivers with a certain probability.In order to improve success probabilities of such multicast remote state preparation using non-maximally entangled channels,we put forward the second scheme,which deals with the situation that is a synchronous transfer of an arbitrary single-qubit state and an arbitrary two-qubit state from one sender to two receivers.In particular,its success probability can reach 100%in principle,and independent of the entanglement degree of the shared non-maximally entangled channel.Notably,in the second scheme,the auxiliary particle is not required.展开更多
In this paper, we present a novel scheme for hierarchical joint remote state preparation(HJRSP) in a deterministic manner, where two senders can jointly and remotely prepare an arbitrary single-qubit at three receiv...In this paper, we present a novel scheme for hierarchical joint remote state preparation(HJRSP) in a deterministic manner, where two senders can jointly and remotely prepare an arbitrary single-qubit at three receivers' port. A six-particle partially entangled state is pre-shared as the quantum channel. There is a hierarchy among the receivers concerning their powers to reconstruct the target state. Due to various unitary operations and projective measurements, the unit success probability can always be achieved irrespective of the parameters of the pre-shared partially entangled state.展开更多
Voltage-controlled quantum dynamics of two quantum-dot molecules(QDMs) embedded in two separated photonic crystal cavities are theoretically investigated. We show numerically that generation of entangled states and po...Voltage-controlled quantum dynamics of two quantum-dot molecules(QDMs) embedded in two separated photonic crystal cavities are theoretically investigated. We show numerically that generation of entangled states and population transfer between the two QDMs can be realized with the same coupling parameters. The effects of parameters deviation and dissipations on generation entangled states and populations transfer are also discussed. The results may be used for realization of new-type of solid state quantum devices and integrated electro-optical devices.展开更多
In this paper, we discuss the concepts of quantum coding and error correction for a five-particle entangled state. Error correction can correct bit-reverse or phase-flip errors of one and two quantum states and is no ...In this paper, we discuss the concepts of quantum coding and error correction for a five-particle entangled state. Error correction can correct bit-reverse or phase-flip errors of one and two quantum states and is no longer limited to only one quantum state. We encode a single quantum state into a five-particle entangled state before being transferred to the sender. We designed an automatic error-correction circuit to correct errors caused by noise. We also simplify the design process for a multiple quantum error-correction circuit. We compare error-correction schemes for five and three entangled particles in terms of efficiency and capabilities. The results show that error-correction efficiency and fidelity are im- proved.展开更多
We discuss the fidelity of states in the infinite-dimensional systems and give an elementary proof of the infinite-dimensional version of Uhlmann's theorem.This theorem is used to generalize several properties of ...We discuss the fidelity of states in the infinite-dimensional systems and give an elementary proof of the infinite-dimensional version of Uhlmann's theorem.This theorem is used to generalize several properties of the fidelity of the finite-dimensional case to the infinite-dimensional case.These are somewhat different from those for the finite-dimensional case.展开更多
基金Project supported by the National Basic Research Program of China (Grant No. 2010CB923202)the Specialized Research Fund for the Doctoral Program of Ministry of Education of China (Grant No.20090005120008)+1 种基金the Fundamental Research Funds for the Central Universities of Chinathe National Natural Science Foundation of China (Grant Nos. 60937003,61178010,and 61205117)
文摘We propose a practical entanglement concentration protocol (ECP) for a hybrid entangled state using quantum dots and a microcavity coupled system. A hybrid less-entangled state can he concentrated to a most-entangled state with a certain probability using only one ancillary single photon. Moreover, using this protocol, we can also concentrate an arbitrary three-particle less-entangled W state using two ancillary photons and classical communication. The proposed protocols provide us with a useful method to concentrate less-entangled states, which can he implemented with current technology.
基金National Natural Science Foundation of China under Grant Nos.10174024 and 10474025
文摘We investigate the generation of entanglement of coherent excitonic states in coupled quantum dots placedin a cavity by meaning of the state preparation fidelity [Nature (London) 404 (2002) 256;Phys.Rev.A 65 (2002) 012107;J.Uffink,Phys.Rev.Lett.88 (2002) 230406.] The effect of the number of exeitons and the coherent intensity |α| of thecavity field on the entanglement is also studied.
基金Project supported by Indian Institute of Engineering Science and Technology, Shibpur, India
文摘We discuss a quantum remote state preparation protocol by which two parties, Alice and Candy, prepare a single-qubit and a two-qubit state, respectively, at the site of the receiver Bob. The single-qubit state is known to Alice while the two-qubit state which is a non-maximally entangled Bell state is known to Candy. The three parties are connected through a single entangled state which acts as a quantum channel. We first describe the protocol in the ideal case when the entangled channel under use is in a pure state. After that, we consider the effect of amplitude damping(AD) noise on the quantum channel and describe the protocol executed through the noisy channel. The decrement of the fidelity is shown to occur with the increment in the noise parameter. This is shown by numerical computation in specific examples of the states to be created. Finally, we show that it is possible to maintain the label of fidelity to some extent and hence to decrease the effect of noise by the application of weak and reversal measurements. We also present a scheme for the generation of the five-qubit entangled resource which we require as a quantum channel. The generation scheme is run on the IBMQ platform.
基金supported by the Program for New Century Excellent Talents at the University of China under Grant No.NCET-06-0554the National Natural Science Foundation of China under Grant Nos.60677001 and 10747146+3 种基金the Science-Technology Fund of Anhui Province for Outstanding Youth under Grant No.06042087the Key Fund of the Ministry of Education of China under Grant No.206063the Natural Science Foundation of Guangdong Province under Grant Nos.06300345 and 7007806Natural Science Foundation of Hubei Province under Grant No.2006ABA354
文摘<Abstract>Recently,several similarprotocols [J.Opt.B 4 (2002) 380;Phys.Lett.A 316 (2003) 159;Phys.Lett.A 355 (2006) 285;Phys.Lett.A 336 (2005) 317] for remotely preparing a class of multi-qubit states (i.e,α|O...O〉 + β|1...1〉) were proposed,respectively.In this paper,by applying the controlled-not (CNOT) gate,a new simple protocol is proposed for remotely preparing such class of states.Compared to the previous protocols,both classical communication cost and required quantum entanglement in our protocol are remarkably reduced.Moreover,the difficulty of identifying some quantum states in our protocol is also degraded.Hence our protocol is more economical and feasible.
文摘We have numerically calculated the thermal entanglement of a two-qubit system at low temperatures in a isotropic Ising chain under an inhomogeneous magnetic field. It is shown that in the homogeneous magnetic field, the two- qubit system has entangled states. It is concluded that the presence of the inhomogeneity in the magnetic field plays an effective role on the entangled states. Finally, it is suggested that the inhomogeneity in the magnetic field can be used to create two separated entangled formations in a two-qubit system.
基金Supported by the National Fundamental Research Program of China(Grant No.2001CB309306)the National Natural Science Foundation of China(Grant Nos.60621064 and 10674127) the Innovation Funds from Chinese Academy of Sciences
文摘It is a simple introduction to quantum entanglement and quantum operations.The authors focus on some applications of quantum entanglement and relations between two-qubit entangled states and unitary operations.It includes remote state preparation by using any pure entangled states,nonlocal operation implementation using entangled states,entanglement capacity of two-qubit gates and two-qubit gates construction.
基金supported by the National Natural Science Foundation of China(Grant Nos.61201253,61373131,61572246,and 61502147)PAPDCICAEET funds
文摘Two schemes are proposed to realize the controlled remote preparation of an arbitrary four-qubit cluster-type state via a partially entangled channel. We construct ingenious measurement bases at the sender’s and the controller’s locations, which play a decisive role in the proposed schemes. The success probabilities can reach 50% and 100%, respectively. Compared with the previous proposals, the success probabilities are independent of the coefficients of the entangled channel.
基金supported by the National Natural Science Foundation of China(Grant No.11264015)
文摘Although the multi-level structure of superconducting qubits may result in calculation errors, it can be rationally used to effectively improve the speed of gate operations. Utilizing a current-biased Josephson junction (A-type rf-SQUID) as a tunable coupler for superconducting transmission line resonators (TLRs), under the large detuning condition, we demonstrate the controllable generation of entangled coherent states in circuit quantum electrodynamics (circuit QED). The coupling between the TLRs and the qubit can be effectively regulated by an external bias current or coupling capacitor. Further investigations indicate that the maximum entangled state can be obtained through measuring the excited state of the superconducting qubits. Then, the influence of the TLR [tecay on the prepared entangled states is analyzed.
文摘We present two schemes for realizing the remote preparation of a Greenberger-Horne-Zeilinger (GHZ) state. The first scheme is to remotely prepare a general N-particle GHZ state with two steps. One is to prepare a qubit state by using finite classical bits from sender to receiver via a two-particle entangled state, and the other is that the receiver introduces N - 1 additional particles and performs N - 1 controlled-not (C-Not) operations. The second scheme is to remotely prepare an N-atom GHZ state via a two-atom entangled state in cavity quantum electrodynamics (QED). The two schemes require only a two-particle entangled state used as a quantum channel, so we reduce the requirement for entanglement.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61372076 and 61301171)the 111 Project(Grant No.B08038)the Fundamental Research Funds for the Central Universities,China(Grant No.K5051201021)
文摘In this paper, two novel schemes for deterministic joint remote state preparation(JRSP) of arbitrary single- and twoqubit states are proposed. A set of ingenious four-particle partially entangled states are constructed to serve as the quantum channels. In our schemes, two senders and one receiver are involved. Participants collaborate with each other and perform projective measurements on their own particles under an elaborate measurement basis. Based on their measurement results,the receiver can reestablish the target state by means of appropriate local unitary operations deterministically. Unit success probability can be achieved independent of the channel's entanglement degree.
基金Project supported by the Key Industry Projects in Shaanxi Province,China(Grant Nos.2019ZDLGY09-03 and 2020ZDLGY15-09)the National Natural Science Foundation of China(Grant Nos.61771296,61372076,and 61301171)+1 种基金the Natural Science Foundation of Shaanxi Province,China(Grant Nos.2018JM60-53 and 2018JZ60-06)the 111 Project(Grant B08038).
文摘Due to the unavoidable interaction between the quantum channel and its ambient environment,it is difficult to generate and maintain the maximally entanglement.Thus,the research on multiparty information transmission via non-maximally entangled channels is of academic value and general application.Here,we utilize the non-maximally entangled channels to implement two multiparty remote state preparation schemes for transmitting different quantum information from one sender to two receivers synchronously.The first scheme is adopted to transmit two different four-qubit cluster-type entangled states to two receivers with a certain probability.In order to improve success probabilities of such multicast remote state preparation using non-maximally entangled channels,we put forward the second scheme,which deals with the situation that is a synchronous transfer of an arbitrary single-qubit state and an arbitrary two-qubit state from one sender to two receivers.In particular,its success probability can reach 100%in principle,and independent of the entanglement degree of the shared non-maximally entangled channel.Notably,in the second scheme,the auxiliary particle is not required.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61701285 and 61701284)the Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents,China(Grant No.2017RCJJ070)China Postdoctoral Science Foundation Funded Project(Grant No.2017M622233)
文摘In this paper, we present a novel scheme for hierarchical joint remote state preparation(HJRSP) in a deterministic manner, where two senders can jointly and remotely prepare an arbitrary single-qubit at three receivers' port. A six-particle partially entangled state is pre-shared as the quantum channel. There is a hierarchy among the receivers concerning their powers to reconstruct the target state. Due to various unitary operations and projective measurements, the unit success probability can always be achieved irrespective of the parameters of the pre-shared partially entangled state.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11004001 and 11105001the Key Project of Chinese Ministry of Education under Grant No.212076the Anhui Provincial Natural Science Foundation under Grant No.1208085QA09
文摘Voltage-controlled quantum dynamics of two quantum-dot molecules(QDMs) embedded in two separated photonic crystal cavities are theoretically investigated. We show numerically that generation of entangled states and population transfer between the two QDMs can be realized with the same coupling parameters. The effects of parameters deviation and dissipations on generation entangled states and populations transfer are also discussed. The results may be used for realization of new-type of solid state quantum devices and integrated electro-optical devices.
基金The project partially supported by National Natural Science Foundation of China under Grant Nos. 90103026 and 60478029 . We would like to acknowledge useful discussions with Prof. Wu Ying.
文摘In this paper, we discuss the concepts of quantum coding and error correction for a five-particle entangled state. Error correction can correct bit-reverse or phase-flip errors of one and two quantum states and is no longer limited to only one quantum state. We encode a single quantum state into a five-particle entangled state before being transferred to the sender. We designed an automatic error-correction circuit to correct errors caused by noise. We also simplify the design process for a multiple quantum error-correction circuit. We compare error-correction schemes for five and three entangled particles in terms of efficiency and capabilities. The results show that error-correction efficiency and fidelity are im- proved.
基金supported by the National Natural Science Foundation of China(Grant Nos.11171249 and 11101250)the Youth Foundation of Shanxi Province(Grant No.2012021004)the Young Talents Plan for Shanxi University and a grant from the International Cooperation Program in Sciences and Technology of Shanxi(Grant No.2011081039)
文摘We discuss the fidelity of states in the infinite-dimensional systems and give an elementary proof of the infinite-dimensional version of Uhlmann's theorem.This theorem is used to generalize several properties of the fidelity of the finite-dimensional case to the infinite-dimensional case.These are somewhat different from those for the finite-dimensional case.