Ratchets from the cold: Brownian motors with cold atoms in optical lattices

Abstract

Brownian motors, or ratchets, are devices which 'rectify' Brownian motion, that is, they can generate a current of particles out of unbiased fluctuations. The present article reviews recent experimental realizations of ratchets employing cold atoms in optical lattices. This is quite an unusual system for a Brownian motor as there is not a real thermal bath, and both the periodic potential for the atoms and the fluctuations are determined by laser fields. Such a system has allowed us to explore a number of fundamental features of ratchets.