Interaction induced directed transport in ac-driven periodic potentials

Abstract

We demonstrate that repulsive power law interactions can induce deterministic directed transport of particles in dissipative ac-driven periodic potentials, in regimes where the underlying noninteracting system exhibits localized oscillations. Contrasting the well-established single particle ratchet mechanism, this interaction induced transport is based on the collective behaviour of the interacting particles yielding a spatiotemporal nonequilibrium pattern comprising persistent travelling excitations.

Pinned-to-sliding transition and structural crossovers for helically confined charges

“…The latter category includes the highly controllable case of trapped ions which can form crystals of different shapes and sizes [17][18][19][20][21] resulting from the interplay between the Coulomb repulsion and the external potential. If the latter is periodic, realized for instance by an optical lattice, it has been shown that most of the properties of the standard FK models can be retrieved [22][23][24] and the corresponding systems are predicted to exhibit interesting transport properties [24][25][26]. Even more, due to their cleanness and the variety of controllable parameters and structures such systems offer a good opportunity to experimentally study the numerous effects predicted for FK models as well as further phenomena connected to microscopic friction or nanofriction [27][28][29].…”

Can a periodically driven particle resist laser cooling and noise?

“…The dynamical mechanism we explored is formally close to models of Hamiltonian and Brownian ratchets [37], which are basic models of transport [38,39]. Transport in a mixed phase-space is especially complex [40][41][42][43][44][45][46] and the ability to control and accurately measure motion in complex time-dependent potentials make ion-trap experiments suitable for quantitative tests of such ideas [21], extended even to many particles [47,48]. Our results can be generalized to frequency-locked limit-cycles in the relative coordinate of two interacting particles [49,50], or in the rotation of a macroscopic particle, with V 2 a periodic function of the rotation angle [51,52].…”

Dimensional coupling-induced current reversal in two-dimensional driven lattices

“…Translating our parameters to experimentally relevant quantities for an optical lattice setup with cold rubidium (Rb 87 ) atoms and 780 nm lasers, we obtain the lattice height V ∼ 22E r , the width 1 √ βx ∼ 252 nm, the driving frequency ω ∼ 10ω r and the driving amplitude d x ∼ 390 nm, where E r and ω r are the recoil energy and recoil frequency of the atom respectively. Interaction , disorder and noise effects [30,44,45], would probably lead to a slow accumulation of particles within the regular portions of the phase space which may also aid them in crossing the regular barrier confining the initial conditions in the quasi 2D case to negative and only weakly positive velocities and may therefore lead to a slight decrease of the reversal time.…”