We study theoretically the essential properties of an exciton in vertically coupled Gaussian quantum dots in the presence of an external magnetic field. The ground state energy of a heavy-hole exciton is split into fo...We study theoretically the essential properties of an exciton in vertically coupled Gaussian quantum dots in the presence of an external magnetic field. The ground state energy of a heavy-hole exciton is split into four energy levels due to the Zeeman effect. For the symmetrical system, the entanglement entropy of the exciton state can reach a value of 1. However, for a system with broken symmetry, it is close to zero. Our results are in good agreement with previous studies.展开更多
We investigate the effects of diferent components of the Dzyaloshinskii-Moriya(DM)anisotropic antisy mnetricinteraction on optimal dense coding with a two-qubit Heisenberg XXZ chain in the presence and in the absenceo...We investigate the effects of diferent components of the Dzyaloshinskii-Moriya(DM)anisotropic antisy mnetricinteraction on optimal dense coding with a two-qubit Heisenberg XXZ chain in the presence and in the absenceof external imagnetic fields.The anisotropic coupling parameter△,isotropic coupling parameter J,and the DMinteraction paraneters are found to be efective for optimal dense coding,while the magnetic field turns out tobe destructive.Moreover,the results show that the case of antiferromagnetic(AFM)is more ideal for optimaldense coding than the case of ferromagnetic(FM)in general.In the case of AFM,by comparison of the two caseswith the sane fixed x-and z-component parameters of DM interaction(D_(x)and D_(z)),the appropriate model foroptimal dense coding is indicated for the different value intervals of△.Comparison of the effects of D_(x)and D_(z)on optimal dense coding is made and their dominant regions are clarified.展开更多
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–Ze...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）.展开更多
We analyze the multipartite entanglement evolution of three-qubit mixed states composed of a GHZ state and a W state. For a composite system consisting of three cavities interacting with independent reservoirs, it is ...We analyze the multipartite entanglement evolution of three-qubit mixed states composed of a GHZ state and a W state. For a composite system consisting of three cavities interacting with independent reservoirs, it is shown that the entanglement evolution is restricted by a set of monogamy relations. Furthermore, as quantified by the negativity, the entanglement dynamical property of the mixed entangled state of cavity photons is investigated. It is found that the three cavity photons can exhibit the phenomenon of entanglement sudden death （ESD）. However, compared with the evolution of a generalized three-qubit GHZ state which has the equal initial entanglement, the ESD time of mixed states is later than that of the pure state. Finally, we discuss the entanglement distribution in the multipartite system, and point out the intrinsic relation between the ESD of cavity photons and the entanglement sudden birth of reservoirs.展开更多
Quantum measurement problem has existed many years and inspired a large of literature in both physics and philosophy,but there is still no conclusion and consensus on it.We show it can be subsumed into the quantum the...Quantum measurement problem has existed many years and inspired a large of literature in both physics and philosophy,but there is still no conclusion and consensus on it.We show it can be subsumed into the quantum theory if we extend the Feynman path integral by considering the relativistic effect of Feynman paths.According to this extended theory,we deduce not only the Klein-Gordon equation,but also the wave-function-collapse equation.It is shown that the stochastic and instantaneous collapse of the quantum measurement is due to the "potential noise" of the apparatus or environment and "inner correlation" of wave function respectively.Therefore,the definite-status of the macroscopic matter is due to itself and this does not disobey the quantum mechanics.This work will give a new recognition for the measurement problem.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61176089 and 10905016)the Natural Science Foundation of Hebei Province, China (Grant Nos. A2011205092 and A2011208010)
文摘We study theoretically the essential properties of an exciton in vertically coupled Gaussian quantum dots in the presence of an external magnetic field. The ground state energy of a heavy-hole exciton is split into four energy levels due to the Zeeman effect. For the symmetrical system, the entanglement entropy of the exciton state can reach a value of 1. However, for a system with broken symmetry, it is close to zero. Our results are in good agreement with previous studies.
基金Supported by the National Science Foundation of China under Grant No 10064004the Priority Subjects Program for Theoretical Physics of XJNU.Jiang-Tao Cai also acknowledges the support of the Science and Technology Innovative Foundation for Graduate Students of XJNU under Grant No 20091204Yan-Kui Bai also acknowledges the support of the National Science Foundation of China under Grant No 10905016.
文摘We investigate the effects of diferent components of the Dzyaloshinskii-Moriya(DM)anisotropic antisy mnetricinteraction on optimal dense coding with a two-qubit Heisenberg XXZ chain in the presence and in the absenceof external imagnetic fields.The anisotropic coupling parameter△,isotropic coupling parameter J,and the DMinteraction paraneters are found to be efective for optimal dense coding,while the magnetic field turns out tobe destructive.Moreover,the results show that the case of antiferromagnetic(AFM)is more ideal for optimaldense coding than the case of ferromagnetic(FM)in general.In the case of AFM,by comparison of the two caseswith the sane fixed x-and z-component parameters of DM interaction(D_(x)and D_(z)),the appropriate model foroptimal dense coding is indicated for the different value intervals of△.Comparison of the effects of D_(x)and D_(z)on optimal dense coding is made and their dominant regions are clarified.
基金supported by the National Natural Science Foundation of China(Grant Nos.61275215 and 10905016)the National Fundamental Research Program of China(Grant No.2011CBA00203)+1 种基金the Fujian Provincial College Funds for Distinguished Young Scientists,China(Grant No.JA14070)the Natural Science Foundation of Hebei Province,China(Grant No.A2012205062)
文摘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）.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10905016 and 10971247)the Natural Science Foundation of Hebei Province of China (Grant Nos. A2012205062,A2012205013,and A2010000344)the Fund of Hebei Normal niversity
文摘We analyze the multipartite entanglement evolution of three-qubit mixed states composed of a GHZ state and a W state. For a composite system consisting of three cavities interacting with independent reservoirs, it is shown that the entanglement evolution is restricted by a set of monogamy relations. Furthermore, as quantified by the negativity, the entanglement dynamical property of the mixed entangled state of cavity photons is investigated. It is found that the three cavity photons can exhibit the phenomenon of entanglement sudden death （ESD）. However, compared with the evolution of a generalized three-qubit GHZ state which has the equal initial entanglement, the ESD time of mixed states is later than that of the pure state. Finally, we discuss the entanglement distribution in the multipartite system, and point out the intrinsic relation between the ESD of cavity photons and the entanglement sudden birth of reservoirs.
基金Supported by the National Basic Research Program of China (973 Program) under Grant No. G2009CB929300the National Natural Science Foundation of China under Grant Nos. 10905016,10874013,60776061 and 60821061
文摘Quantum measurement problem has existed many years and inspired a large of literature in both physics and philosophy,but there is still no conclusion and consensus on it.We show it can be subsumed into the quantum theory if we extend the Feynman path integral by considering the relativistic effect of Feynman paths.According to this extended theory,we deduce not only the Klein-Gordon equation,but also the wave-function-collapse equation.It is shown that the stochastic and instantaneous collapse of the quantum measurement is due to the "potential noise" of the apparatus or environment and "inner correlation" of wave function respectively.Therefore,the definite-status of the macroscopic matter is due to itself and this does not disobey the quantum mechanics.This work will give a new recognition for the measurement problem.
