paper

Return probability after a quench from a domain wall initial state in the spin-1/2 XXZ chain

arXiv:1707.06625 · doi:10.1088/1742-5468/aa8c19

Abstract

We study the return probability and its imaginary () time continuation after a quench from a domain wall initial state in the XXZ spin chain, focusing mainly on the region with anisotropy . We establish exact Fredholm determinant formulas for those, by exploiting a connection to the six vertex model with domain wall boundary conditions. In imaginary time, we find the expected scaling for a partition function of a statistical mechanical model of area proportional to , which reflects the fact that the model exhibits the limit shape phenomenon. In real time, we observe that in the region the decay for large times is nowhere continuous as a function of anisotropy: it is either gaussian at root of unity or exponential otherwise. As an aside, we also determine that the front moves as , by analytic continuation of known arctic curves in the six vertex model. Exactly at , we find the return probability decays as . It is argued that this result provides an upper bound on spin transport. In particular, it suggests that transport should be diffusive at the isotropic point for this quench.

33 pages, 8 figures. v2: typos fixed, references added. v3: minor changes

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