Martínez Pedro J, Chacón Ricardo
Instituto de Nanociencia y Materiales de Aragón, CSIC-Universidad de Zaragoza, E-50009 Zaragoza, Spain.
Departamento de Física Aplicada, E.I.N.A., Universidad de Zaragoza, E-50018 Zaragoza, Spain.
Phys Rev E. 2021 Aug;104(2-1):024224. doi: 10.1103/PhysRevE.104.024224.
Directed ratchet transport is generally observed in nonautonomous systems as a result of the interplay of nonlinearity, symmetry breaking, and nonequilibrium fluctuations. Here we demonstrate that ratchet dynamics can appear in significant transporting degrees of freedom of dissipative coupled systems without external bias due to unidirectional coupling of oscillatory degrees of freedom (which are also nonbiasing in any direction), while optimal enhancement of directed ratchet transport occurs when the initial conditions and parameters of such ratcheting degrees of freedom are suitably chosen as predicted by the theory of ratchet universality. The simple case of linear oscillatory degrees of freedom is discussed in detail, and numerical experiments are described which confirm all the theoretical predictions, including the dependence of current (velocity) reversals on the initial conditions and the ratcheting degrees-of-freedom parameters. This autonomous ratchet scenario could be exploited technologically, for instance, in the context of noncontact, rack-and-pinion type, nanoscale setups with coupling from the lateral Casimir force, and is relevant for studies of molecular motors in the biological realm.
由于非线性、对称性破缺和非平衡涨落之间的相互作用，定向棘轮输运通常在非自治系统中被观察到。在这里，我们证明了由于振荡自由度的单向耦合（其在任何方向上也不产生偏置），棘轮动力学可以出现在无外部偏置的耗散耦合系统的显著输运自由度中，而当根据棘轮普遍性理论适当地选择这种棘轮自由度的初始条件和参数时，定向棘轮输运可实现最优增强。本文详细讨论了线性振荡自由度的简单情况，并描述了数值实验，这些实验证实了所有理论预测，包括电流（速度）反转对初始条件和棘轮自由度参数的依赖性。这种自主棘轮方案可以在技术上加以利用，例如，在具有横向卡西米尔力耦合的非接触、齿条齿轮式纳米级装置的背景下，并且与生物领域中分子马达的研究相关。
