52,509 research outputs found
Accurate determination of tensor network state of quantum lattice models in two dimensions
We have proposed a novel numerical method to calculate accurately the
physical quantities of the ground state with the tensor-network wave function
in two dimensions. We determine the tensor network wavefunction by a projection
approach which applies iteratively the Trotter-Suzuki decomposition of the
projection operator and the singular value decomposition of matrix. The norm of
the wavefunction and the expectation value of a physical observable are
evaluated by a coarse grain renormalization group approach. Our method allows a
tensor-network wavefunction with a high bond degree of freedom (such as D=8) to
be handled accurately and efficiently in the thermodynamic limit. For the
Heisenberg model on a honeycomb lattice, our results for the ground state
energy and the staggered magnetization agree well with those obtained by the
quantum Monte Carlo and other approaches.Comment: 4 pages 5 figures 2 table
Superfluid-Mott-Insulator Transition in a One-Dimensional Optical Lattice with Double-Well Potentials
We study the superfluid-Mott-insulator transition of ultracold bosonic atoms
in a one-dimensional optical lattice with a double-well confining trap using
the density-matrix renormalization group. At low density, the system behaves
similarly as two separated ones inside harmonic traps. At high density,
however, interesting features appear as the consequence of the quantum
tunneling between the two wells and the competition between the "superfluid"
and Mott regions. They are characterized by a rich step-plateau structure in
the visibility and the satellite peaks in the momentum distribution function as
a function of the on-site repulsion. These novel properties shed light on the
understanding of the phase coherence between two coupled condensates and the
off-diagonal correlations between the two wells.Comment: 5 pages, 7 figure
The evolution-dominated hydrodynamic model and the pseudorapidity distributions in high energy physics
By taking into account the effects of leading particles, we discuss the
pseudorapidity distributions of the charged particles produced in high energy
heavy ion collisions in the context of evolution-dominated hydrodynamic model.
The leading particles are supposed to have a Gaussian rapidity distribution
normalized to the number of participants. A comparison is made between the
theoretical results and the experimental measurements performed by BRAHMS and
PHOBOS Collaboration at BNL-RHIC in Au-Au and Cu-Cu collisions at sqrt(s_NN)
=200 GeV and by ALICE Collaboration at CERN-LHC in Pb-Pb collisions at
sqrt(s_NN) =2.76 TeV.Comment: 17 pages,4 figures, 2 table
The Equation of State and Quark Number Susceptibility in Hard-Dense-Loop Approximation
Based on the method proposed in [ H. S. Zong, W. M. Sun, Phys. Rev. \textbf{D
78}, 054001 (2008)], we calculate the equation of state (EOS) of QCD at zero
temperature and finite quark chemical potential under the hard-dense-loop (HDL)
approximation. A comparison between the EOS under HDL approximation and the
cold, perturbative EOS of QCD proposed by Fraga, Pisarski and Schaffner-Bielich
is made. It is found that the pressure under HDL approximation is generally
smaller than the perturbative result. In addition, we also calculate the quark
number susceptibility (QNS) at finite temperature and finite chemical potential
under hard-thermal/dense-loop (HTL/HDL) approximation and compare our results
with the corresponding ones in the previous literature.Comment: 12 pages, 3 figure
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