玻色-爱因斯坦凝聚体中的双孤子相互作用操控

考虑周期性驱动线性势, 利用Darboux变换法解析地研究了玻色-爱因斯坦凝聚体(BEC)中的双孤子相互作用, 得到了S-波散射长度的临界值. 结果表明: 当S-波散射长度高于临界值时, BEC中的两个亮孤子相互吸引并融合; 而当S-波散射长度低于临界值时, 两个亮孤子保持局域稳定. 此外, 在外部势阱的驱动下, 两个稳定的亮孤子产生周期性振荡行为.     

锂离子电池材料的中子衍射研究

 历史上每一次人类社会的重大进步都伴随着能源的变革。化石能源的利用给人类社会带来极大便利的同时,也对我们赖以生存的自然环境造成了巨大破坏,发展绿色、清洁、高效的可替代能源是当代科技工作者肩负的重要使命。当前,各国都在加大对核能、太阳能、风能、生物能、水能等清洁能源的开发力度,大量的人力和物力投入到这一能源变革之中。     

Calculation of scattering parameters for ultracold 6Li-TLi elastic collisions＊

This paper theoretically studies the elastic scattering properties in a mixture of 6Li and 7Li atoms at cold and ultracold temperatures. Based on the constructed accurate interatomic potential of the triplet state for 6Li7Li mixture by the mass scaling method, it calculates the interspecies s-wave scattering lengths and the p-wave scattering lengths by the variable phase method and the semiclassical method, respectively. The scattering length is in good agreement with the experiment. The partial-wave and total cross sections are also calculated and a rich resonance structure is found.     

中子引起氘核破裂反应的实验研究

对25 MeV中子引起氘核破裂反应的中子-中子准自由散射和17.36 MeV中子引起氘核破裂反应的中子-中子末态相互作用进行了细致的研究。首先,以小于5%的不确定度,精确测量了25MeV中子-中子准自由散射出射的中子三重微分截面。实验数据用基于现实核子-核子势(CD-Bonn,Argonne!18,Nijm I和II)的理论计算配合Monte-Carlo模拟进行了分析。实验结果比基于CD-Bonn势的理论预言高(16.0±4.6)%,进一步证实了目前的理论在中子-中子准自由散射方面还无法准确描述实验数据。其次,通过运动学非完全测量,精确测量了17.36 MeV中子引起氘核破裂反应在0°角附近出射的质子能谱,用基于现实核子-核子势(CD-Bonn、Bonn-B和Nijm I)的理论计算以及Monte-Carlo模拟分析了所测得的质子能谱,确定了中子-中子散射长度ann=(-16.8±0.6)fm。     

费米-费米散射长度对费米超流气体在幺正极限区域的隧穿现象影响

运用双势阱模型通过调节费米-费米散射长度研究了超流费米气体在幺正极限区域的隧穿现象. 研究发现费米-费米散射长度对量子隧穿效应有显著的影响. 在确定的区域, 可以得到在双势阱中完全的量子隧穿现象, 而在另一些区域, 这种隧穿就完全消失. 由于在实验室中超流费米气体的散射长度是可以调节的, 所以在实验上可以实现通过调节散射长度来控制超流费米气体的宏观隧穿现象.     

Effect of Time-Dependent Atomic Scattering Length on Solitons in Bose-Einstein Condensates with a Complex Potential

We consider the one-dimensional nonlinear Schrǒdinger equations that describe the dynamics of a Bose-Einstein Condensates with time-dependent scattering length in a complex potential. Our results show that as long as the integrable relation is satisfied, exact solutions of the one-dimensional nonlinear Schrǒdinger equation can be found in a general closed form, and interactions between two solitons are modulated in a complex potential We find that the changes of the scattering length and trapping potential can be effectively used to control the interaction between two bright soliton.     

Elastic Scattering of Ultracold 23Na and 39K Atoms in the Singlet State

The elastic scattering properties for collisions between ultracold 23Na and 39K atoms in the singlet state are investigated. Based on the recent theoretical and experimental results, the improved hybrid potential is presented for the singlet X1Σg＋ ground state of NaK. By means of the Numerov and semiclassical methods, the values of the s-wave scattering length a for the singlet state are calculated to be 33.3757a0 and 37.9399a0, respectively. Pronounced shape resonances appear for the l = 1 partial wave for the X1Σg＋ state. In addition, the s-wave scattering cross section, total cross section and energy positions of shape resonances for the X1Σg＋ state are discussed.     

应用变相法研究超冷镁原子的弹性散射特性

本文基于参考文献[5]构建的精确的基态Mg_2的势能曲线,应用变相法对超冷温度下Mg原子的弹性散射特性进行了系统的研究.计算得到Mg原子碰撞的散射长度和有效力程分别为25.9a_0和191.3a_0,其中a_0是玻尔半径;低能极限下镁原子间的弹性碰撞主要为s-波碰撞,同时计算得到的基态Mg_2支持束缚态的数目为19.计算结果与文献[5]和Numerov法所得结果一致.     

The Lowest Order Relativistic Corrections for K^-p Two-Body Problem

A two-body equation of the kaon-proton system with the lowest order relativistic corrections is derived and solved. The scattering lengths and the energy of an unstable bound state are calculated.