Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: "Light-cone" dynamics after quantum quenches in spin chains   Signal propagation in the non equilibirum evolution after quantum quenches
has recently attracted much experimental and theoretical interest. A key
question arising in this context is what principles, and which of the
properties of the quench, determine the characteristic propagation velocity.
Here we investigate such issues for a class of quench protocols in one of the
central paradigms of interacting many-particle quantum systems, the spin-1/2
Heisenberg XXZ chain. We consider quenches from a variety of initial thermal
density matrices to the same final Hamiltonian using matrix product state
methods. The spreading velocities are observed to vary substantially with the
initial density matrix. However, we achieve a striking data collapse when the
spreading velocity is considered to be a function of the excess energy. Using
the fact that the XXZ chain is integrable, we present an explanation of the
observed velocities in terms of "excitations" in an appropriately defined
generalized Gibbs ensemble.

16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
22
The categories of this paper are: chao-dyn
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
3
The categories of this paper are: physics