The Ratchet effect in an ageing glass

We study the dynamics of an asymmetric intruder in a glass-former model. At equilibrium, the intruder diffuses with average zero velocity. After an abrupt quench to $T$ deeply under the mode-coupling temperature, a net average drift is observed, steady on a logarithmic time-scale. The phenomenon is well reproduced in an asymmetric version of the Sinai model. The subvelocity of the intruder grows with $T_{eff}\mathrm{/}T$, where $T_{eff}$ is defined by the response-correlation ratio, corresponding to a general behavior of thermal ratchets when in contact with two thermal reservoirs.