中文摘要：

采用含时哈特里-福克-博戈留波夫近似研究雪茄形铷原子玻色-爱因斯坦凝聚中单极子模的朗道阻尼和频移.通过考虑元激发的实际弛豫及其各弛豫间的正交关系改进原有方法,并由此给出计算朗道阻尼和频移的新公式.此外,令凝聚体边界处动能密度为零代替令基态能量极小以改进原消除三模耦合矩阵元的方法.通过这些改进,同时计算阻尼和频移,并讨论它们的温度依赖,所得理论结果都与实验符合.

英文摘要：

The Landau damping and frequency-shift of monopole mode in an elongated-rubidium Bose-Einstein condensate are investigated by using the time-dependent Hartree-Fock-Bogoliubov approximation. Improving the previous approach, We have taken into account the practical relaxations of elementary excitations and the orthogonal relation among them. With such an approach, we provide a new calculation formula for Landau damping rate and frequency-shift. In addition, our previous method of eliminating the divergence in three-mode coupling matrix elements is also improved by zeroing the kinetic energy at the condensate boundary instead of minimizing the ground-state energy. Based on these improvements, both the Landau damping rate and the frequency-shift of the monopole mode are analytically calculated and their temperature dependences are also discussed. And all the theoretical results are in agree meat with experimental data.