14 research outputs found
Entanglement Mean Field Theory and the Curie-Weiss Law
The mean field theory, in its different hues, form one of the most useful
tools for calculating the single-body physical properties of a many-body
system. It provides important information, like critical exponents, of the
systems that do not yield to an exact analytical treatment. Here we propose an
entanglement mean field theory (EMFT) to obtain the behavior of the two-body
physical properties of such systems. We apply this theory to predict the phases
in paradigmatic strongly correlated systems, viz. the transverse anisotropic
XY, the transverse XX, and the Heisenberg models. We find the critical
exponents of different physical quantities in the EMFT limit, and in the case
of the Heisenberg model, we obtain the Curie-Weiss law for correlations. While
the exemplary models have all been chosen to be quantum ones, classical
many-body models also render themselves to such a treatment, at the level of
correlations.Comment: 5 pages, 4 figure
SU(N) Quantum Hall Skyrmions
We have investigated skyrmions in N-component quantum Hall systems. We find
that SU(N) skyrmions are the lowest energy charged excitations for filling
factors \nu = 1,2,...,N-1 for small enough symmetry breaking terms. N>2
skyrmions can be realized in Si QH systems based on the (110) or (111)
interfaces of Si, or perhaps in Si (100) systems, where the spin and valley
isospin together provide an SU(4)-symmetry, or in multilayer QH systems. We
also present Hartree-Fock results for a phenomenological easy-axis
SU(2)-breaking model appropriate to valley degeneracy.Comment: 5 pages, 2 figure
Diblock copolymers at a homopolymer-homopolymer-interface: a Monte Carlo simulation
The properties of diluted symmetric A-B diblock copolymers at the interface
between A and B homopolymer phases are studied by means of Monte Carlo (MC)
simulations of the bond fluctuation model. We calculate segment density
profiles as well as orientational properties of segments, of A and B blocks,
and of the whole chain. Our data support the picture of oriented ``dumbbells'',
which consist of mildly perturbed A and B Gaussian coils. The results are
compared to a self consistent field theory (SCFT) for single copolymer chains
at a homopolymer interface. We also discuss the number of interaction contacts
between monomers, which provide a measure for the ``active surface'' of
copolymers or homopolymers close to the interface