SciPost Phys. 8, 037 (2020) ·
published 6 March 2020
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We study the time evolution of magnetization and entanglement for initial
states with local excitations, created upon the ferromagnetic ground state of
the XY chain. For excitations corresponding to a single or two well separated
domain walls, the magnetization profile has a simple hydrodynamic limit, which
has a standard interpretation in terms of quasiparticles. In contrast, for a
spin-flip we obtain an interference term, which has to do with the nonlocality
of the excitation in the fermionic basis. Surprisingly, for the single domain
wall the hydrodynamic limit of the entropy and magnetization profiles are found
to be directly related. Furthermore, the entropy profile is additive for the
double domain wall, whereas in case of the spin-flip excitation one has a
nontrivial behaviour.
Viktor Eisler, Florian Maislinger, Hans Gerd Evertz
SciPost Phys. 1, 014 (2016) ·
published 30 December 2016
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We study the melting of domain walls in the ferromagnetic phase of the
transverse Ising chain, created by flipping the order-parameter spins along
one-half of the chain. If the initial state is excited by a local operator in
terms of Jordan-Wigner fermions, the resulting longitudinal magnetization
profiles have a universal character. Namely, after proper rescalings, the
profiles in the noncritical Ising chain become identical to those obtained for
a critical free-fermion chain starting from a step-like initial state. The
relation holds exactly in the entire ferromagnetic phase of the Ising chain and
can even be extended to the zero-field XY model by a duality argument. In
contrast, for domain-wall excitations that are highly non-local in the
fermionic variables, the universality of the magnetization profiles is lost.
Nevertheless, for both cases we observe that the entanglement entropy
asymptotically saturates at the ground-state value, suggesting a simple form of
the steady state.
Dr Eisler: "We thank the referee for the c..."
in Report on Front dynamics in the XY chain after local excitations