Coherent Destruction of Tunneling of Dipolar Bosonic Gas

The tunneling dynamics of a dipolar bosonic gas with repulsive interactions in a periodically driven triple- well are investigated. Because of the coupled effect of long-range dipole-dipole interaction and the short-range of on-site interaction, the increase of the repulsive atomic interactions can either suppress tunneling or enhance tunneling and, thus, the system experiences rich coherent tunneling（CT）-coherent destruction of tunneling （CDT） transitions. In particular, as the repulsive atomic interactions increase, the system can undergo CT-CDT-CT- CDT or CDT-CT-CDT-CT-CDT transitions. This cannot occur in non-dipolar gas, where the increase of the repulsive atomic interaction only suppress tunneling and the system can only undergo CT-CDT transition. We further present a good understanding of the results with the help of the quasi-energy spectrum of the system.     

超流Fermi气体在非简谐势阱中的集体激发

研究了非谐振势中超流Fermi气体的集体激发. 基于一维超流流体动力学模型, 采用变分法获得了体系从分子Bose-Einstein凝聚端渡越到Cooper对凝聚端时系统的两个低能激发模, 即偶极模和呼吸模. 分析发现: 在整个跨越区偶极模和呼吸模都发生了频移现象, 且在BCS端频移更加显著. 进一步研究发现在不同驱动振幅激发下超流Fermi气体质量中心和宽度变化呈现出了复杂动力学特性, 由于非谐振势的贡献,超流Fermi气体两低能模发生耦合, 使宽度变化产生量子拍频现象, 且拍频频率随着驱动振幅的增加而增大. 这种非线性耦合对外部驱动的响应在幺正区尤其显著. 关键词： 超流Fermi气体 非谐振势 集体激发     

Tunneling dynamics of a few bosons with both two-and three-body interactions in a double-well potential

We investigate the tunneling dynamics of a few bosons with both two-and three-body interactions in a doublewell potential. Uncorrelated tunneling of Rabi oscillation with the minimum period can happen only when the two-and three-body interactions satisfy a critical condition, i.e., the effective interaction energy is minimized. When the atomic interactions are slightly away from the critical condition in the weak interaction regime, the uncorrelated tunneling exhibits collapse-revival character. When the atomic interactions are strong and far away from the critical condition, the correlated tunneling with Rabi oscillation occurs. The tunneling period(the period of collapse-revival) increases(decreases) when the rate between the two-body and three-body interactions is away from the corresponding critical condition or when the number of bosons increases. Further, the tunneling properties are understood with the help of the energy spectrum of the system. Eventually, the effect of the initial configuration on the tunneling dynamics of a few bosons for both odd and even numbers of bosons is studied, which results in intriguing consequences.     

Tunneling Dynamics of Dipolar Bosonic System with Periodically Modulated s-wave Scattering

Within the mean-field three-site Bose-Hubbard model, the tunneling dynamics of dipolar bosonic gas with a periodically modulation of s-wave scattering is investigated. The system experiences complex and rich coherent tunneling （CT）-coherent destruction of tunneling （CDT） transitions resulting from the correlated effect among the next-neighbor dipole-dipole interaction, the on-site interaction and the modulated s-wave scattering. In particular, The region of the modulated s-wave scattering for generating CT （CDT） is the widest （narrowest） when the on-site interaction and the next-neighbor dipole-dipole interaction have some correlated values, which are closely related to the tunneling energy and the interaction energy of the system. The correlated values for appearing CDT can be theoreticaJly gained from the tunneling energy and the interaction energy of the system.     

玻色-费米超流混合体系中的相互作用调制隧穿动力学

研究了玻色-费米超流混合体系中的相互作用调制隧穿动力学特性,其中玻色子位于对称双势阱中,费米子位于对称双势阱中心的简谐势阱中.采用双模近似方法得到描述双势阱玻色-爱因斯坦凝聚的动力学特性方程组,并将其与简谐势阱中分子玻色-爱因斯坦凝聚的Gross-Pitaevskii方程进行耦合.通过对不同参数下玻色-费米混合体系中的隧穿现象进行数值研究,发现简谐势阱中费米子与双势阱中玻色子的相互作用使双势阱玻色-爱因斯坦凝聚的隧穿动力学特性更加丰富.不但驱使双势阱中玻色-爱因斯坦凝聚从类约瑟夫森振荡转变为宏观量子自囚禁,而且宏观量子自囚禁表现为三种不同的形式:相位与时间呈负相关并随时间单调减小的自囚禁、相位随时间演化有界的自囚禁以及相位与时间呈正相关并随时间单调增大的自囚禁.