The thermal quantum discord （QD） is studied in a two-qubit Heisenberg XXZ system with DzyaloshinskiiMoriya （DM） interaction. We compare the thermal QD with thermal entanglement in this system and find remarkable d...The thermal quantum discord （QD） is studied in a two-qubit Heisenberg XXZ system with DzyaloshinskiiMoriya （DM） interaction. We compare the thermal QD with thermal entanglement in this system and find remarkable differences between them. For instance, we show situations where QD decreases asymptotically to zero with temperature T while entanglement decreases to zero at the point of critical temperature, situations where QD decreases with certain tunable parameters such as Dx and Dx when entanglement increases. We find that the characteristic of QD is exotic in this system and this possibly offers a potential solution to enhance entanglement of a system. We also show that tunable parameter Dx is more efficient than parameter Dz in most regions for controlling the QD.展开更多
This paper is based on Einstein’s supposition about crystal lattice vibration, which states that when Einstein’s temperature ΘE is not less than the crystal temperature T but less than 2T, the expression of crystal...This paper is based on Einstein’s supposition about crystal lattice vibration, which states that when Einstein’s temperature ΘE is not less than the crystal temperature T but less than 2T, the expression of crystal molar heat capacity changes to the Dulong-Petit equation Cv=3R. Thereby this equation can explain why crystal molar heat capacity equals about 3R not only at low temperatures but also at normal temperatures for many kinds of metals. It can be calculated that the nonlinear interaction among atoms contributes to the molar heat capacity using the coefficient of expansion β and the Grüneisen constant γ. The result is that the relative error between the theoretical and the experimental value of the molar heat capacity is reduced greatly for many kinds of metals, especially for metals of IA. The relative error can be cut by about 17%.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos.90503009,10775116973 Program under Grant No.2005CB724508
文摘The thermal quantum discord （QD） is studied in a two-qubit Heisenberg XXZ system with DzyaloshinskiiMoriya （DM） interaction. We compare the thermal QD with thermal entanglement in this system and find remarkable differences between them. For instance, we show situations where QD decreases asymptotically to zero with temperature T while entanglement decreases to zero at the point of critical temperature, situations where QD decreases with certain tunable parameters such as Dx and Dx when entanglement increases. We find that the characteristic of QD is exotic in this system and this possibly offers a potential solution to enhance entanglement of a system. We also show that tunable parameter Dx is more efficient than parameter Dz in most regions for controlling the QD.
文摘This paper is based on Einstein’s supposition about crystal lattice vibration, which states that when Einstein’s temperature ΘE is not less than the crystal temperature T but less than 2T, the expression of crystal molar heat capacity changes to the Dulong-Petit equation Cv=3R. Thereby this equation can explain why crystal molar heat capacity equals about 3R not only at low temperatures but also at normal temperatures for many kinds of metals. It can be calculated that the nonlinear interaction among atoms contributes to the molar heat capacity using the coefficient of expansion β and the Grüneisen constant γ. The result is that the relative error between the theoretical and the experimental value of the molar heat capacity is reduced greatly for many kinds of metals, especially for metals of IA. The relative error can be cut by about 17%.
