Driven Ratchets for Cold Atoms

TL;DR

This paper reviews recent experimental realizations of ac driven ratchets using cold atoms in optical lattices, highlighting their unique non-thermal system dynamics and the investigation of symmetry and transport phenomena.

Contribution

It presents novel experimental implementations of rocking and gating ratchets with cold atoms, exploring symmetry-transport relationships in non-thermal optical lattice systems.

Findings

Successful realization of rocking and gating ratchets with cold atoms

Demonstrated the influence of symmetry on transport properties

Analyzed periodic and quasiperiodic driving effects

Abstract

Brownian motors, or ratchets, are devices which "rectify" Brownian motion, i.e. they can generate a current of particles out of unbiased fluctuations. The ratchet effect is a very general phenomenon which applies to a wide range of physical systems, and indeed ratchets have been realized with a variety of solid state devices, with optical trap setups as well as with synthetic molecules and granular gases. The present article reviews recent experimental realizations of ac driven ratchets with cold atoms in driven optical lattices. This is quite an unusual system for a Brownian motor as there is no a real thermal bath, and both the periodic potential for the atoms and the fluctuations are determined by laser fields. Such a system allowed us to realize experimentally rocking and gating ratchets, and to precisely investigate the relationship between symmetry and transport in these ratchets, both for the case of periodic and quasiperiodic driving.