5,456 research outputs found
Particle number conservation in quantum many-body simulations with matrix product operators
Incorporating conservation laws explicitly into matrix product states (MPS)
has proven to make numerical simulations of quantum many-body systems much less
resources consuming. We will discuss here, to what extent this concept can be
used in simulation where the dynamically evolving entities are matrix product
operators (MPO). Quite counter-intuitively the expectation of gaining in speed
by sacrificing information about all but a single symmetry sector is not in all
cases fulfilled. It turns out that in this case often the entanglement imposed
by the global constraint of fixed particle number is the limiting factor.Comment: minor changes, 18 pages, 5 figure
Phase Diagram of the 1D Kondo Lattice Model
We determine the boundary of the fully polarized ferromagnetic ground state
in the one dimensional Kondo lattice model at partial conduction electron band
filling by using a newly developed infinite size DMRG method which conserves
the total spin quantum number. The obtained paramagnetic to ferromagnetic phase
boundary is below for the whole range of band filling. By this
we solve the controversy in the phase diagram over the extent of the
ferromagnetic region close to half filling.Comment: 6 pages, 4 EPS figures. Presented at MOS9
Neurophysiology
Contains a report on a research project.Bell Telephone Laboratories, IncorporatedTeagle FoundationNational Science Foundatio
Magnetism in the dilute Kondo lattice model
The one dimensional dilute Kondo lattice model is investigated by means of
bosonization for different dilution patterns of the array of impurity spins.
The physical picture is very different if a commensurate or incommensurate
doping of the impurity spins is considered. For the commensurate case, the
obtained phase diagram is verified using a non-Abelian density-matrix
renormalization-group algorithm. The paramagnetic phase widens at the expense
of the ferromagnetic phase as the -spins are diluted. For the incommensurate
case, antiferromagnetism is found at low doping, which distinguishes the dilute
Kondo lattice model from the standard Kondo lattice model.Comment: 11 pages, 2 figure
Quasiparticles in the Kondo lattice model at partial fillings of the conduction band
We study the spectral properties of the one-dimensional Kondo lattice model
as function of the exchange coupling, the band filling, and the quasimomentum
in the ferromagnetic and paramagnetic phase. Using the density-matrix
renormalization group method, we compute the dispersion relation of the
quasiparticles, their lifetimes, and the Z-factor. As a main result, we provide
evidence for the existence of the spinpolaron at partial band fillings. We find
that the quasiparticle lifetime differs by orders of magnitude between the
ferromagnetic and paramagnetic phase and depends strongly on the quasimomentum.Comment: 9 pages, 9 figure
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