Cold atom ratchets

Ferruccio Renzoni, UCL

Friday 29 October 2010, 1500-1600
C1 Physics Building

Brownian motors, or ratchets, are devices which "rectify" Brownian motion, i.e. they can generate a current of particles out of unbiased fluctuations. We experimentally implemented a Brownian motor using cold atoms in an optical lattice. 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.

With the help of such a system, we investigated experimentally the relationship between symmetry and transport in a 1D rocking ratchet, both in the periodic and in the quasiperiodic case. We then went beyond 1D rocking ratchets, demonstrating 1D gating ratchets. We also realized 2D rocking ratchets and demonstrated a rectification mechanism unique to these high-dimensional ratchets.