Speer David, Eichhorn Ralf, Evstigneev Mykhaylo, Reimann Peter
Universität Bielefeld, Fakultät für Physik, 33615 Bielefeld, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2012 Jun;85(6 Pt 1):061132. doi: 10.1103/PhysRevE.85.061132. Epub 2012 Jun 28.
We consider two coupled particles moving along a periodic substrate potential with negligible inertia effects (overdamped limit). Even when the particles are identical and the substrate spatially symmetric, a sinusoidal external driving of appropriate amplitude and frequency may lead to spontaneous symmetry breaking in the form of a permanent directed motion of the dimer. Thermal noise restores ergodicity and thus zero net velocity, but entails arbitrarily fast diffusion of the dimer for sufficiently weak noise. Moreover, upon application of a static bias force, the dimer exhibits a motion opposite to that force (absolute negative mobility). The key requirement for all these effects is a nonconvex interaction potential of the two particles.
我们考虑两个沿着周期性衬底势运动的耦合粒子，其惯性效应可忽略不计（过阻尼极限）。即使粒子是相同的且衬底在空间上是对称的，适当振幅和频率的正弦外部驱动也可能导致二聚体以永久定向运动的形式出现自发对称性破缺。热噪声恢复遍历性，从而使净速度为零，但对于足够弱的噪声，会导致二聚体任意快速扩散。此外，施加静态偏置力时，二聚体表现出与该力相反的运动（绝对负迁移率）。所有这些效应的关键要求是两个粒子的非凸相互作用势。
