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中国物理学会期刊

自旋-轨道耦合玻色凝聚体中的自旋频谱动力学响应

CSTR: 32037.14.aps.74.20241783

Dynamical response of spin frequency spectrum in spin-orbit coupled Bose-Einstein condensate

CSTR: 32037.14.aps.74.20241783
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  • 基于自旋-轨道耦合玻色凝聚体, 提出了一种凝聚体的自旋频谱对外场调控参数的动力学响应效应. 该效应由对凝聚体的快速晃动和外加的迅变塞曼场来驱动. 研究发现, 自旋频谱的谱峰对外场驱动参数呈现出简单的线性关系. 通过对模型作适当近似和简化, 本文给出了该线性关系的解析关系式. 同时, 基于Gross-Pitaevskii方程对系统的动力学演化做了数值计算, 数值结果与解析表达式符合得很好. 另外, 本文还进一步探究了自旋频谱对外场驱动响应的物理本质, 发现该效应来源于不同自旋-轨道态之间的量子干涉, 可以利用量子多臂干涉仪的图像来理解其内涵. 文章的最后对方案的实验可行性及相关参数进行了讨论与估计. 本文的结果在量子控制和量子计量学等领域有潜在价值.

     

    Dynamical characteristics of internal and external states of a Bose-Einstein condensate are generally different and independent, thus requiring different experimental manipulation techniques. The spin-orbit coupling recently achieved in Bose-Einstein condensates essentially connects spin and motion degree of freedom, endowing spin states with the ability to respond to orbital manipulation, and vice versa. In this work, a dynamical response effect, induced by simultaneously manipulating the internal and external states of a spin-orbit-coupled Bose-Einstein condensate, is predicted. Here, the “simultaneously manipulating the internal and external states” means that the driving field combines the Zeeman field applied to the internal state of the atom and the orbital potential affecting the external states of the atom. Specifically, the Bose-Einstein condensate is assumed to be activated by an abruptly applied Zeeman field and a sudden shake of the trapping potential. After some reasonable simplification and approximation of the model (i.e. neglecting the inter-atomic interactions and modelling the shake of the trapping potential by a short time-dependent pulse), an analytical relationship connecting spin frequency spectrum and the parameters of the driving fields is derived. The numerical calculations based on directly integrating the Gross-Pitaevskii equation are in good agreement with the results from the analytical relationship. The physical origin of the predicted spin dynamical response can be traced back to the quantum interference among different spin-orbit states. Due to the fact that a series of characteristic parameters of the condensate can be manifested in the spin frequency spectrum, the dynamical response effect predicted here provides a candidate method for determining and calibrating various system parameters by measuring the spin frequency spectrum.

     

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