133 research outputs found
Interaction Quenches of Fermi Gases
It is shown that the jump in the momentum distribution of Fermi gases evolves
smoothly for small and intermediate times once an interaction between the
fermions is suddenly switched on. The jump does not vanish abruptly. The loci
in momentum space where the jumps occur are those of the noninteracting Fermi
sea. No relaxation of the Fermi surface geometry takes place.Comment: 4 pages, 1 figur
Spectral Densities from Dynamic Density-Matrix Renormalization
Dynamic density-matrix renormalization provides valuable numerical
information on dynamic correlations by computing convolutions of the
corresponding spectral densities. Here we discuss and illustrate how and to
which extent such data can be deconvolved to retrieve the wanted spectral
densities. We advocate a nonlinear deconvolution scheme which minimizes the
bias in the ansatz for the spectral density. The procedure is illustrated for
the line shape and width of the Kondo peak (low energy feature) and for the
line shape of the Hubbard satellites (high energy feature) of the single
impurity Anderson model. It is found that the Hubbard satellites are strongly
asymmetric.Comment: RevTeX 4, 11 pages, 7 eps figures; published versio
Effective One-Dimensional Models from Matrix Product States
In this paper we present a method for deriving effective one-dimensional
models based on the matrix product state formalism. It exploits translational
invariance to work directly in the thermodynamic limit. We show, how a
representation of the creation operator of single quasi-particles in both real
and momentum space can be extracted from the dispersion calculation. The method
is tested for the analytically solvable Ising model in a transverse magnetic
field. Properties of the matrix product representation of the creation operator
are discussed and validated by calculating the one-particle contribution to the
spectral weight. Results are also given for the ground state energy and the
dispersion.Comment: 17 pages, 8 figure
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