205,067 research outputs found
Stripes, topological order, and deconfinement in a planar t-Jz model
We determine the quantum phase diagram of a two-dimensional bosonic t-Jz
model as a function of the lattice anisotropy gamma, using a quantum Monte
Carlo loop algorithm. We show analytically that the low-energy sectors of the
bosonic and the fermionic t-Jz models become equivalent in the limit of small
gamma. In this limit, the ground state represents a static stripe phase
characterized by a non-zero value of a topological order parameter. This phase
remains up to intermediate values of gamma, where there is a quantum phase
transition to a phase-segregated state or a homogeneous superfluid with dynamic
stripe fluctuations depending on the ratio Jz/t.Comment: 4 pages, 5 figures (2 in color). Final versio
Angular Momentum and Mutually Unbiased Bases
The Lie algebra of the group SU(2) is constructed from two deformed
oscillator algebras for which the deformation parameter is a root of unity.
This leads to an unusual quantization scheme, the {J2,Ur} scheme, an
alternative to the familiar {J2,Jz} quantization scheme corresponding to common
eigenvectors of the Casimir operator J2 and the Cartan operator Jz. A
connection is established between the eigenvectors of the complete set of
commuting operators {J2,Ur} and mutually unbiased bases in spaces of constant
angular momentum.Comment: To be published in International Journal of Modern Physics
Limitations of Absolute Current Densities Derived from the Semel & Skumanich Method
Semel and Skumanich proposed a method to obtain the absolute electric current
density, |Jz|, without disambiguation of 180 degree in the transverse field
directions. The advantage of the method is that the uncertainty in the
determination of the ambiguity in the magnetic azimuth is removed. Here, we
investigate the limits of the calculation when applied to a numerical MHD
model. We found that the combination of changes in the magnetic azimuth with
vanishing horizontal field component leads to errors, where electric current
densities are often strong. Where errors occur, the calculation gives |Jz| too
small by factors typically 1.2 ~ 2.0.Comment: 10 pages, 4 figures. To appear on Science in China Series G: Physics,
Mechanics & Astronomy, October 200
The uterine junctional zone: A 3-dimensional ultrasound study of patients with endometriosis
The uterine junctional zone (JZ) alterations are correlated with adenomyosis. An accurate evaluation of the JZ may be obtained by 3-dimensional transvaginal sonography (TVS). The aim of the present prospective study was to assess the value of detectable alterations by 3-dimensional TVS of the JZ in patients with pelvic endometriosis (diagnosed by laparoscopy and histologic condition) and to compare these findings with those of women without pelvic endometriosis
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