The mixedness of the N-qubit quantum states with exchange symmetry has been studied, and the results show that the linear entropy of the single qubit reduced density matrix （RDM）, which can describe the mixedness, i...The mixedness of the N-qubit quantum states with exchange symmetry has been studied, and the results show that the linear entropy of the single qubit reduced density matrix （RDM）, which can describe the mixedness, is completely determined by the expectation values 〈Sz〉 and 〈S±〉 for both the pure and the mixed states. The mixedness of the pure states can be used to describe the bipartite entanglement, as an example we have calculated the mixedness of the Dicke state and the spin squeezed Kitagawa-Ueda state. For the mixed states, we determine the mixedness properties of both the ground states and the thermal states in mean-field clusters of spin-1/2 particles interacting via the anisotropy Heisenberg XXZ interaction, and found for the ferromagnetic case （J 〈 0）, the mixedness will approximate to the pairwise entanglement when the anisotropic parameter △ 〉 △c.展开更多
The resource theories of quantum coherence attract a lot of attentioI2 in recent years. Especially, the monotonicity property plays a crucial role here. In this paper we investigate the monotonicity property for the c...The resource theories of quantum coherence attract a lot of attentioI2 in recent years. Especially, the monotonicity property plays a crucial role here. In this paper we investigate the monotonicity property for the coherence measures induced by the Rdnyi a-relative entropy, which present in [Phys. Rev. A 94 （2016） 052336]. We show that the Rdnyi a-relative entropy of coherence does not in general satisfy the monotonicity requirement under the subselection of measurements condition and it also does not satisfy the extension of monotonicity requirement, which presents in [Phys. Rev. A 93 （2016） 032136]. Due to the Rdnyi a-relative entropy of coherence can act as a coherence monotone quantifier, we examine the trade-off relations between coherence and mixedness. Finally, some properties for the single qubit of Rdnyi 2-relative entropy of coherence are derived.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No 10547008)Specialized Research Program of Education Bureau of Shaanxi Province (Grant No 08JK434)the Youth Foundation of Xi’an Institute of Posts and Telecommunications (Grant No ZL2008-11)
文摘The mixedness of the N-qubit quantum states with exchange symmetry has been studied, and the results show that the linear entropy of the single qubit reduced density matrix （RDM）, which can describe the mixedness, is completely determined by the expectation values 〈Sz〉 and 〈S±〉 for both the pure and the mixed states. The mixedness of the pure states can be used to describe the bipartite entanglement, as an example we have calculated the mixedness of the Dicke state and the spin squeezed Kitagawa-Ueda state. For the mixed states, we determine the mixedness properties of both the ground states and the thermal states in mean-field clusters of spin-1/2 particles interacting via the anisotropy Heisenberg XXZ interaction, and found for the ferromagnetic case （J 〈 0）, the mixedness will approximate to the pairwise entanglement when the anisotropic parameter △ 〉 △c.
基金Supported by National Natural Science Foundation of China under Grant Nos.11271237,11671244,61671280the Higher School Doctoral Subject Foundation of Ministry of Education of China under Grant No.20130202110001+1 种基金Fundamental Research Funds for the Central Universities(GK201502004 and 2016CBY003)the Academic Leaders and Academic Backbones,Shaanxi Normal University under Grant No.16QNGG013
文摘The resource theories of quantum coherence attract a lot of attentioI2 in recent years. Especially, the monotonicity property plays a crucial role here. In this paper we investigate the monotonicity property for the coherence measures induced by the Rdnyi a-relative entropy, which present in [Phys. Rev. A 94 （2016） 052336]. We show that the Rdnyi a-relative entropy of coherence does not in general satisfy the monotonicity requirement under the subselection of measurements condition and it also does not satisfy the extension of monotonicity requirement, which presents in [Phys. Rev. A 93 （2016） 032136]. Due to the Rdnyi a-relative entropy of coherence can act as a coherence monotone quantifier, we examine the trade-off relations between coherence and mixedness. Finally, some properties for the single qubit of Rdnyi 2-relative entropy of coherence are derived.
