1,553 research outputs found
Entanglement Spectra of the quantum hard-square model: Holographic minimal models
We study the entanglement properties of a quantum lattice-gas model for which
we can find the exact ground state (of the Rokhsar-Kivelson type). The ground
state can be expressed as a superposition of states, each of which is
characterized by a particle configuration with nearest-neighbor exclusion. We
show that the reduced density matrix of the model on a ladder is intimately
related to the transfer matrix of the classical hard-square model. The
entanglement spectra of the model on square and triangular ladders are critical
when parameters are chosen so that the corresponding classical hard-square
models are critical. A detailed analysis reveals that the critical theories for
the entanglement Hamiltonians are minimal conformal field theories. We
further show that the entanglement Hamiltonian for the triangular ladder is
integrable despite the fact that the original quantum lattice-gas model is
non-integrable.Comment: 10 pages, 8 figure
Ensuring access to essential services : demand-side housing subsidies
This paper examines the strengths and weaknesses of demand-side subsidy approaches for improving poor households'access to housing services. It begins with a discussion of the rationale for stand-alone housing assistance programs, and a description of the ongoing transition away from traditional supply-side housing assistance to demand-side subsidies. The paper presents model demand-side approaches, but also draws on real world examples to highlight various aspects of program design related to targeting, transparency, price distortion, institutional capacity, administrative complexity, and funding. It also describes how variations in the design of housing-related subsidy programs can appear in response to philosophical, political, and resource considerations. The paperconcludes with a discussion of the appropriateness of different subsidy approaches for various situations.Banks&Banking Reform,Housing&Human Habitats,Public Sector Economics,Municipal Financial Management,Public&Municipal Finance
Exact Analysis of Entanglement in Gapped Quantum Spin Chains
We investigate the entanglement properties of the valence-bond-solid states
with generic integer-spin . Using the Schwinger boson representation of the
valence-bond-solid states, the entanglement entropy, the von Neumann entropy of
a subsystem, is obtained exactly and its relationship with the usual
correlation function is clarified. The saturation value of the entanglement
entropy, , is derived explicitly and is interpreted in terms of
the edge-state picture. The validity of our analytical results and the
edge-state picture is numerically confirmed. We also propose a novel
application of the edge state as a qubit for quantum computation.Comment: 4 pages, 2 figure
Topological Invariants for Polyacetylene, Kagome and Pyrochlore lattices
Adiabatic invariants by quantized Berry phases are defined for gapped
electronic systems in -dimensions (). This series includes
Polyacetylene, Kagome and Pyrochlore lattice respectively for and 3.
The invariants are quantum -multimer order parameters to characterize the
topological phase transitions by the multimerization. This fractional
quantization is protected by the global equivalence. As for the chiral
symmetric case, a topological form of the -invariant is explicitly given
as well.Comment: 4 pgages, 4 figure
Exact supersymmetry in the relativistic hydrogen atom in general dimensions -- supercharge and the generalized Johnson-Lippmann operator
A Dirac particle in general dimensions moving in a 1/r potential is shown to
have an exact N = 2 supersymmetry, for which the two supercharge operators are
obtained in terms of (a D-dimensional generalization of) the Johnson-Lippmann
operator, an extension of the Runge-Lenz-Pauli vector that relativistically
incorporates spin degrees of freedom. So the extra symmetry (S(2))in the
quantum Kepler problem, which determines the degeneracy of the levels, is so
robust as to accommodate the relativistic case in arbitrary dimensions.Comment: 4 pages, 1 figur
On the magic square C*-algebra of size 4
In this paper, we investigate the structure of the magic square C*-algebra (4) of size 4. We show that a certain twisted crossed product of (4) is isomorphic to the homogeneous C*-algebra 4 ( ()). Using this result, we show that (4) is isomorphic to the fixed point algebra of 4 ( ()) by a certain action. From this concrete realization of (4), we compute the K-groups of (4) and their generators
Topological Classification of Gapped Spin Chains :Quantized Berry Phase as a Local Order Parameter
We characterize several phases of gapped spin systems by local order
parameters defined by quantized Berry phases. This characterization is
topologically stable against any small perturbation as long as the energy gap
remains finite. The models we pick up are dimerized Heisenberg chains
and S=2 Heisenberg chains with uniaxial single-ion-type anisotropy.
Analytically we also evaluate the topological local order parameters for the
generalized Affleck-Kennedy-Lieb-Tasaki (AKLT) model. The relation between the
present Berry phases and the fractionalization in the integer spin chains are
discussed as well.Comment: 6 pages, 4 figures, accepted for publication in Phys. Rev.
Internal magnetic field effect on magnetoelectricity in orthorhombic crystals
We have investigated the role of the 4 moment on the magnetoelectric (ME)
effect of orthorhombic MnO (=rare earth ions). In order to clarify
the role of the 4 moment, we prepared three samples: (Eu,Y)MnO without
the 4 moment, TbMnO with the anisotropic 4 moment, and
(Gd,Y)MnO with the isotropic 4 moment. The ferroelectric behaviors of
these samples are different from each other in a zero magnetic field.
(Eu,Y)MnO and (Gd,Y)MnO show the ferroelectric polarization along
the a axis in the ground state, while TbMnO shows it along the c axis.
Such difference may arise from the influence of the anisotropic Tb 4
moment. The direction of the ferroelectric polarization of MnO is
determined by the internal magnetic field arising from the 4 moment.Comment: 2 pages, 1 figure, the proceeding of International Conference of
Magnetism, to be published in the Journal of Magnetism and Magnetic Material
Thermal performance analysis of a new structured-core translucent vacuuminsulation panel in comparison to vacuum glazing: Experimental and theoretically validated analyses
The notion at which, nowadays, building sector is being recognized to be nearly zero-energy buildings (NZEBs) relies partly on the thermal performance of its fabric insulation. Vacuum glazing (VG) technology attracted the research interest as an option to reduce heat loss through windows. However, the total glazing thermal transmittance (U-value) for VG increases with the use of smaller glazing area due to the edge-seal effects, due to the thermal short-circuit around the edges and the overall construction cost of VG leading to an unaffordable option to deal with energy conservation of buildings. Therefore, this study aims to propose a new structured core transparent vacuum insulation panel (TVIP) to accomplish insulation for the windows without edge sealing effect, with lower cost and can be easily retrofitted to the conventional windows of the existing buildings. To do this, VG and TVIP were constructed and their thermal conductivity were measured using heat flow meter apparatus.
In addition, a 3D finite volume model considering the effect of surface to surface radiation, gas conduction, and thermal bridges through the spacer material and sealing material is developed. The model is validated
with the experiments in this work and with the data for VG in the literature. The effect of vacuum pressure increase is simulated to mimic the vacuum deterioration problem and the effect of glazing size on the
insulation performance of both VG and TVIP were investigated. The results indicate that for a smaller glazing area of less than 30 cm × 30 cm, the TVIP accomplished lower U-value compared with the VG at vacuum
pressure of 0.1 Pa and 1 Pa. While, at a vacuum pressure of 10 Pa, the TVIP attained a lower U-value over the entire range of the investigated glazing sizes. Further, the edge-seal effect in the VG is diminished with the use of TVIP. Furthermore, the material cost per unit area of the TVIP is three times less than the cost of VG at laboratory scale. The results of the current study can guide vacuum window designers and researchers to further enhance the performance of TVIP based window to compete for the VG in the markets
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