75 research outputs found
Universal properties of hard-core bosons confined on one-dimensional lattices
Based on an exact treatment of hard-core bosons confined on one-dimensional
lattices, we obtain the large distance behavior of the one-particle density
matrix, and show how it determines the occupation of the lowest natural orbital
in the thermodynamic limit. We also study the occupation of
the natural orbitals for large- at low densities. Both quantities show
universal behavior independently of the confining potential. Finite-size
corrections and the momentum distribution function for finite systems are also
analyzed.Comment: Revtex file, 5 pages, 5 figures. Content and references added.
Published versio
Fermionization in an expanding 1D gas of hard-core bosons
We show by means of an exact numerical approach that the momentum
distribution of a free expanding gas of hard-core bosons on a one-dimensional
lattice approaches to the one of noninteracting fermions, acquiring a Fermi
edge. Yet there is a power-law decay of the one-particle density matrix
, as usual for hard-core bosons in the ground state,
which accounts for a large occupation of the lowest natural orbitals for all
expansion times. The fermionization of the momentum distribution function,
which is not observed in equilibrium, is analyzed in detail.Comment: Revtex file, 4 pages, 6 figures, published versio
Confinement control by optical lattices
It is shown that the interplay of a confining potential with a periodic
potential leads for free particles to states spatially confined on a fraction
of the total extension of the system. A more complex `slicing' of the system
can be achieved by increasing the period of the lattice potential. These
results are especially relevant for fermionic systems, where interaction
effects are in general strongly reduced for a single species at low
temperatures.Comment: Revtex file, 13 pages, 18 figures. References added. Published
versio
Single hole dynamics in the one dimensional t-J model
We present a new finite-temperature quantum Monte Carlo algorithm to compute
imaginary-time Green functions for a single hole in the t-J model on
non-frustrated lattices. Spectral functions are then obtained with the Maximum
Entropy method. Simulations of the one-dimensional case show that a simple
charge-spin separation Ansatz is able to describe the overall features of the
spectral function over the whole energy range for values of J/t from 1/3 to 4.
This includes the bandwidth W \sim 4t + J and the compact support of the
spectral function. The quasiparticle weight Z_k is computed on lattices up to
L=96 sites, and scales as Z_k\propto L^{-1/2}.Comment: 8 pages, 5 figure
Time evolution of one-dimensional Quantum Many Body Systems
The level of current understanding of the physics of time-dependent strongly
correlated quantum systems is far from complete, principally due to the lack of
effective controlled approaches. Recently, there has been progress in the
development of approaches for one-dimensional systems. We describe recent
developments in the construction of numerical schemes for general
(one-dimensional) Hamiltonians: in particular, schemes based on exact
diagonalization techniques and on the density matrix renormalization group
method (DMRG). We present preliminary results for spinless fermions with
nearest-neighbor-interaction and investigate their accuracy by comparing with
exact results.Comment: Contribution for the conference proceedings of the "IX. Training
Course in the Physics of Correlated Electron Systems and High-Tc
Superconductors" held in Vietri sul Mare (Salerno, Italy) in October 200
Ground-state properties of hard-core bosons confined on one-dimensional optical lattices
We study the ground-state properties of hard-core bosons trapped by arbitrary
confining potentials on one-dimensional optical lattices. A recently developed
exact approach based on the Jordan-Wigner transformation is used. We analyze
the large distance behavior of the one-particle density matrix, the momentum
distribution function, and the lowest natural orbitals. In addition, the
low-density limit in the lattice is studied systematically, and the results
obtained compared with the ones known for the hard-core boson gas without the
lattice.Comment: RevTex file, 14 pages, 22 figures, published versio
Quantum Monte Carlo study of confined fermions in one-dimensional optical lattices
Using quantum Monte Carlo (QMC) simulations we study the ground-state
properties of the one-dimensional fermionic Hubbard model in traps with an
underlying lattice. Since due to the confining potential the density is space
dependent, Mott-insulating domains always coexist with metallic regions, such
that global quantities are not appropriate to describe the system. We define a
local compressibility that characterizes the Mott-insulating regions and
analyze other local quantities. It is shown that the momentum distribution
function, a quantity that is commonly considered in experiments, fails in
giving a clear signal of the Mott-insulator transition. Furthermore, we analyze
a mean-field approach to these systems and compare it with the numerically
exact QMC results. Finally, we determine a generic form for the phase diagram
that allows us to predict the phases to be observed in the experiments.Comment: RevTex file, 13 pages, 19 figures, published versio
Time evolution of correlations in strongly interacting fermions after a quantum quench
Using the adaptive time-dependent density matrix renormalization group, we
study the time evolution of density correlations of interacting spinless
fermions on a one-dimensional lattice after a sudden change in the interaction
strength. Over a broad range of model parameters, the correlation function
exhibits a characteristic light-cone-like time evolution representative of a
ballistic transport of information. Such behavior is observed both when
quenching an insulator into the metallic region and also when quenching within
the insulating region. However, when a metallic state beyond the quantum
critical point is quenched deep into the insulating regime, no indication for
ballistic transport is observed. Instead, stable domain walls in the density
correlations emerge during the time evolution, consistent with the predictions
of the Kibble-Zurek mechanism.Comment: Published version; minor changes, references adde
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