42,904 research outputs found
Reply to the Comment on "Enhancement of the Tunneling Density of States in Tomonaga-Luttinger Liquids"
In their comment Fabrizio and Gogolin dispute our result of the enhancement
of the tunneling density of states in a Tomonaga-Luttinger liquid at the
location of a backward scattering defect [Phys. Rev. Lett. 76, 4230(1996);
cond-mat/9601020]. They state that the anticommutativity of the fermion
operators of the left and right moving electrons was not considered properly in
the Letter. We show in the Reply that the result of the Letter can be
reproduced following the Comment when its calculations are performed correctly.
This clearly indicates that the question about the anticommutation relations
was raised by Fabrizio and Gogolin without serious grounds.Comment: Published in PRL as a Reply to the Comment by Fabrizio and Gogolin
(cond-mat/9702080
The Out-of-Equilibrium Time-Dependent Gutzwiller Approximation
We review the recently proposed extension of the Gutzwiller approximation, M.
Schiro' and M. Fabrizio, Phys. Rev. Lett. 105, 076401 (2010), designed to
describe the out-of-equilibrium time-evolution of a Gutzwiller-type variational
wave function for correlated electrons. The method, which is strictly
variational in the limit of infinite lattice-coordination, is quite general and
flexible, and it is applicable to generic non-equilibrium conditions, even far
beyond the linear response regime. As an application, we discuss the quench
dynamics of a single-band Hubbard model at half-filling, where the method
predicts a dynamical phase transition above a critical quench that resembles
the sharp crossover observed by time-dependent dynamical mean field theory. We
next show that one can actually define in some cases a multi-configurational
wave function combination of a whole set of mutually orthogonal Gutzwiller wave
functions. The Hamiltonian projected in that subspace can be exactly evaluated
and is equivalent to a model of auxiliary spins coupled to non-interacting
electrons, closely related to the slave-spin theories for correlated electron
models. The Gutzwiller approximation turns out to be nothing but the mean-field
approximation applied to that spin-fermion model, which displays, for any
number of bands and integer fillings, a spontaneous symmetry breaking
that can be identified as the Mott insulator-to-metal transition.Comment: 25 pages. Proceedings of the Hvar 2011 Workshop on 'New materials for
thermoelectric applications: theory and experiment
Efficient implementation of the Gutzwiller variational method
We present a self-consistent numerical approach to solve the Gutzwiller
variational problem for general multi-band models with arbitrary on-site
interaction. The proposed method generalizes and improves the procedure derived
by Deng et al., Phys. Rev. B. 79 075114 (2009), overcoming the restriction to
density-density interaction without increasing the complexity of the
computational algorithm. Our approach drastically reduces the problem of the
high-dimensional Gutzwiller minimization by mapping it to a minimization only
in the variational density matrix, in the spirit of the Levy and Lieb
formulation of DFT. For fixed density the Gutzwiller renormalization matrix is
determined as a fixpoint of a proper functional, whose evaluation only requires
ground-state calculations of matrices defined in the Gutzwiller variational
space. Furthermore, the proposed method is able to account for the symmetries
of the variational function in a controlled way, reducing the number of
variational parameters. After a detailed description of the method we present
calculations for multi-band Hubbard models with full (rotationally invariant)
Hund's rule on-site interaction. Our analysis shows that the numerical
algorithm is very efficient, stable and easy to implement. For these reasons
this method is particularly suitable for first principle studies -- e.g., in
combination with DFT -- of many complex real materials, where the full
intra-atomic interaction is important to obtain correct results.Comment: 19 pages, 7 figure
Superconductivity in the doped bilayer Hubbard model
We study by the Gutzwiller approximation the melting of the valence bond
crystal phase of a bilayer Hubbard model at sufficiently large inter-layer
hopping. We find that a superconducting domain, with order parameter
, being the inter-layer direction and the intra-layer one,
is stabilized variationally close to the half-filled non-magnetic Mott
insulator. Superconductivity exists at half-filling just at the border of the
Mott transition and extends away from half-filling into a whole region till a
critical doping, beyond which it gives way to a normal metal phase. This result
suggests that superconductivity should be unavoidably met by liquefying a
valence bond crystal, at least when each layer is an infinite coordination
lattice and the Gutzwiller approximation becomes exact. Remarkably, this same
behavior is well established in the other extreme of two-leg Hubbard ladders,
showing it might be of quite general validity.Comment: 9 pages, 5 figure
Electronic correlations stabilize the antiferromagnetic Mott state in CsC
CsC in the A15 structure is an antiferromagnet at ambient pressure
in contrast with other superconducting trivalent fullerides. Superconductivity
is recovered under pressure and reaches the highest critical temperature of the
family. Comparing density-functional calculations with generalized gradient
approximation to the hybrid functional HSE, which includes a suitable component
of exchange, we establish that the antiferromagnetic state of CsC is
not due to a Slater mechanism, and it is stabilized by electron correlation.
HSE also reproduces the pressure-driven metalization. Our findings corroborate
previous analyses suggesting that the properties of this compound can be
understood as the result of the interplay between electron correlations and
Jahn-Teller electron-phonon interaction.Comment: 4 pages, 3 figure
Electron interference and entanglement in coupled 1D systems with noise
We estimate the role of noise in the formation of entanglement and in the
appearance of single- and two-electron interference in systems of coupled
one-dimensional channels semiconductors. Two cases are considered: a
single-particle interferometer and a two-particle interferometer exploiting
Coulomb interaction. In both of them, environmental noise yields a
randomization of the carrier phases. Our results assess how that the
complementarity relation linking single-particle behavior to nonlocal
quantities, such as entanglement and environment-induced decoherence, acts in
electron interferometry. We show that, in a experimental implementation of the
setups examined, one- and two-electron detection probability at the output
drains can be used to evaluate the decoherence phenomena and the degree of
entanglement.Comment: 12 pages, 6 figures. v2: added some references and corrected tex
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