Speaker
Prof.
Angelo Vulpiani
(Dipartimento di Fisica, Università di Roma "La Sapienza")
Description
We study how the Einstein relation between spontaneous
fluctuations and the response to an external perturbation
holds in the absence of currents, for the comb model and the
elastic single-file, which are examples of systems with
subdiffusive transport properties. The relevance of
non-equilibrium conditions is investigated: when a
stationary current (in the form of a drift or an energy
flux) is present, the Einstein relation breaks down, as is
known to happen in systems with standard diffusion. In the
case of the comb model, a general relation, which has
appeared in the recent literature, between the response
function and an unperturbed suitable correlation function,
allows us to explain the observed results. This suggests
that a relevant ingredient in breaking the Einstein formula,
for stationary regimes, is not the anomalous diffusion but
the presence of currents driving the system out of equilibrium.
Primary author
Prof.
Angelo Vulpiani
(Dipartimento di Fisica, Università di Roma "La Sapienza")
