We propose a transport mechanism for overdamped diffusing particles. The mechanism is based on a position-dependent mobility and on breaking detailed balance. Using a two-state model, we show that the transport direction is given by the phase shift between mobility and potential or mobility and transition rate. No symmetry breaking potential as employed in ratchet-type transport models is needed.

• Received 28 April 1999

DOI:https://doi.org/10.1103/PhysRevE.62.272