Explosive condensation in nonequilibrium systems
Martin EVANS, School of Physics and Astronomy, Univ. of Edinburgh
In this talk I will discuss condensation in the zero range process (ZRP) and related models. The ZRP is a simple model of interacting classical particles hopping between sites of a one-dimensional lattice, but with rates that do not obey detailed balance and thus generate a nonequilibrium state. Real-space condensation is the phenomenon whereby a finite fraction of the particles are typically found at a single site in the limit of a large system size. I’ll show how and why condensation arises and how it is related to large deviations of sums of random variables. I’ll also discuss a variation of the model exhibiting `explosive condensation’ – the condensate moves rapidly through the system and the relaxation time to the stationary state decreases to zero for large system size. This provides a first example of instantaneous gelation in a spatially extended system. If time permits I will also discuss how condensation generally arises when there are two constraints – say the sum and the variance – on a collection of random variables.