Directed ratchet transport of cold atoms and fluxons driven by biharmonic fields: A unified view

Abstract

This paper discusses two retrodictions of the theory of ratchet universality which explain previous experimental results concerning directed ratchet transport of cold atoms in dissipative optical lattices in one case and of fluxons in uniform annular Josephson junctions in the other, both driven by biharmonic fields. It has to be emphasized that these retrodictions are in sharp contrast with the current standard explanation of such experimental results, and they offer optimal control of the ratchetlike motion of such entities. New experimental proposals with cold atoms and fluxons are discussed, providing additional tests for novel predictions from ratchet universality.

Ratchet universality in coupled dissipative oscillators without external bias

“…The effectiveness of RU theory has been demonstrated in diverse physical contexts. Instances are cold atoms in optical lattices [22,23], topological solitons [10], Bose-Einstein condensates exposed to a sawtoothlike optical lattice potential [24], matterwave solitons [25], one-dimensional granular chains [26], Brownian particles moving on a periodic substrate subjected to a homogeneous temporal biharmonic excitation [27][28][29], Bose-Einstein condensates under an unbiased periodic driving potential [30], and driven overdamped Brownian particles subjected to a vibrating periodic potential [31]. Also, numerical analyses of a driven Brownian particle in the presence of non-Gaussian noise [32] and coupled Brownian motors with stochastic interactions in a crowded environment [33] have confirmed the RU predictions, and RU has recently been demonstrated in the bidirectional escape from a symmetric potential well [34].…”