Dynamics of a dimer in a symmetric potential: ratchet effect generated by an internal degree of freedom.
Dynamics of a dimer in a symmetric potential: ratchet effect generated by an internal degree of freedom.
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DOI：
10.1103/physreve.77.031136
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发表时间：
2008-03
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影响因子：
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通讯作者：
Sebastian von Gehlen;M. Evstigneev;P. Reimann
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文献类型：
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作者：
Sebastian von Gehlen;M. Evstigneev;P. Reimann
本文研究了由两个谐波耦合组分组成的二聚体的一维动力学。二聚体组分之间的相互距离起着内部自由度的作用。这两个组件都与相同的热浴接触，并耦合到一个空间周期性的，对称的潜力，其振幅在时间上周期性调制，其耦合强度是不同的两个组件。在没有任何外部偏置的情况下，棘轮效应（定向运输）一般会出现，除非二聚体组分的相互耦合趋于零或无穷大。换言之，棘轮效应是由内部自由度产生的。二聚体的速度和扩散系数的精确解析近似。通过添加最佳量的噪声和通过将驱动频率调谐到最佳值来最大化系统的速度。此外，存在一个最佳耦合强度，在该强度下速度最大。
The one-dimensional dynamics of a dimer consisting of two harmonically coupled components is considered. The mutual distance between the dimer components plays the role of an internal degree of freedom. Both components are in contact with the same heat bath and are coupled to a spatially periodic, symmetric potential, whose amplitude is modulated periodically in time and whose coupling strength is different for the two components. In the absence of any external bias, a ratchet effect (directed transport) arises generically unless the mutual coupling of the dimer components tends to zero or infinity. In other words, the ratchet effect is generated by the internal degree of freedom. An accurate analytical approximation for the dimer's velocity and diffusion coefficient is obtained. The velocity of the system is maximized by adding an optimal amount of noise and by tuning the driving frequency to an optimal value. Furthermore, there exists an optimal coupling strength at which the velocity is the largest.