Directed transport in equilibrium

Abstract

We investigate a symmetry broken dimer constrained to move in a particular direction when in contact with a heat-bath at a constant temperature. The dimer is not driven by any external force. The system gains kinetic energy from the heat-bath. The symmetry broken system can use this energy in directed transport. At the hard core collision limit between the particles of the dimer, we show by exact analytic calculations and complementary numerical results that the dimer undergoes steady directed transport. Our observation, being consistent with the {\it second law of thermodynamics}, {\it detailed balance} etc leads to new physical understanding to which much attention has not been paid.