Mean-field spin-oscillation dynamics beyond the single-mode approximation for a harmonically trapped spin-1 Bose-Einstein condensate
Mean-field spin-oscillation dynamics beyond the single-mode approximation for a harmonically trapped spin-1 Bose-Einstein condensate
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DOI：
10.1103/physreva.102.023324
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发表时间：
2020-08
影响因子：
2.9
通讯作者：
J. Jie;Q. Guan;S. Zhong;A. Schwettmann;D. Blume
中科院分区：
文献类型：
--
作者：
J. Jie;Q. Guan;S. Zhong;A. Schwettmann;D. Blume
与单组分玻色-爱因斯坦凝聚相比，旋量玻色-爱因斯坦凝聚具有更丰富的动力学性质。除了密度振荡，旋量玻色-爱因斯坦凝聚体表现出有趣的自旋动力学，这是与不同的超精细组件之间的人口转移。这项工作分析了广泛采用的单模近似的有效性时，描述的自旋动力学响应淬火的系统哈密顿量。单模近似假设不同的超精细态都共享相同的时间无关的空间模式。这意味着所得到的自旋哈密顿量只依赖于自旋相互作用强度，而不依赖于密度相互作用强度。以f=1$超精细流形中的旋量钠玻色-爱因斯坦凝聚为例，在平均场理论框架下，数值计算发现，在某些参数区域，单模近似忽略了自旋和空间动力学的复杂细节.我们开发了一个物理图像来解释所观察到的现象。此外，利用由单模近似描述的布居振荡进入平均场旋量所感受到的有效势，我们导出了一个半定量条件，当动态平均场诱导的单模近似修正是相关的。我们的平均场结果对各种已发表和计划的实验研究有影响。
Compared to single-component Bose-Einstein condensates, spinor Bose-Einstein condensates display much richer dynamics. In addition to density oscillations, spinor Bose-Einstein condensates exhibit intriguing spin dynamics that is associated with population transfer between different hyperfine components. This work analyzes the validity of the widely employed single-mode approximation when describing the spin dynamics in response to a quench of the system Hamiltonian. The single-mode approximation assumes that the different hyperfine states all share the same time-independent spatial mode. This implies that the resulting spin Hamiltonian only depends on the spin interaction strength and not on the density interaction strength. Taking the spinor sodium Bose-Einstein condensate in the $f=1$ hyperfine manifold as an example and working within the mean-field theory framework, it is found numerically that the single-mode approximation misses, in some parameter regimes, intricate details of the spin and spatial dynamics. We develop a physical picture that explains the observed phenomenon. Moreover, using that the population oscillations described by the single-mode approximation enter into the effective potential felt by the mean-field spinor, we derive a semi-quantitative condition for when dynamical mean-field induced corrections to the single-mode approximation are relevant. Our mean-field results have implications for a variety of published and planned experimental studies.