178 research outputs found
Coexistence of Anomalous and Normal Diffusion in Integrable Mott Insulators
We study the finite-momentum spin dynamics in the one-dimensional XXZ spin
chain within the Ising-type regime at high temperatures using density
autocorrelations within linear response theory and real-time propagation of
nonequilibrium densities. While for the nonintegrable model results are well
consistent with normal diffusion, the finite-size integrable model unveils the
coexistence of anomalous and normal diffusion in different regimes of time. In
particular, numerical results show a Gaussian relaxation at smallest nonzero
momenta which we relate to nonzero stiffness in a grand canonical ensemble. For
larger but still small momenta normal-like diffusion is recovered. Similar
results for the model of impenetrable particles also help to resolve rather
conflicting conclusions on transport in integrable Mott insulators.Comment: 5 pages, 4 figure
The Friedel oscillations in the presence of transport currents
We investigate the Friedel oscillations in a nanowire coupled to two
macroscopic electrodes of different potentials. We show that the wave-length of
the density oscillations monotonically increases with the bias voltage, whereas
the amplitude and the spatial decay exponent of the oscillations remain intact.
Using the nonequilibrium Keldysh Green functions, we derive an explicit formula
that describes voltage dependence of the wave-length of the Friedel
oscillations.Comment: 5 pages, 3 figures, RevTe
Nonequilibrium propagation and decay of a bound pair in driven t-J models
We perform an accurate time-dependent numerical study of out-of-equilibrium
response of a bound state within t-J systems on a two-leg ladder and a square
lattice. We show that the bound hole pair decays with the onset of finite
steady current if both mechanisms for binding and the dissipation share
matching degrees of freedom. Moreover, by investigating the mechanism of decay
on the square lattice we find that the dynamics is governed by the decay in the
direction perpendicular to the electric field, leading to much shorter decay
times in comparison to the ladder where such dynamics is topologically
restricted
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