9,794 research outputs found
Criticality in Translation-Invariant Parafermion Chains
In this work we numerically study critical phases in translation-invariant
parafermion chains with both nearest- and next-nearest-neighbor
hopping terms. The model can be mapped to a spin model with
nearest-neighbor couplings via a generalized Jordan-Wigner transformation and
translation invariance ensures that the spin model is always self-dual. We
first study the low-energy spectrum of chains with only nearest-neighbor
coupling, which are mapped onto standard self-dual clock models.
For we match the numerical results to the known conformal field
theory(CFT) identification. We then analyze in detail the phase diagram of a
chain with both nearest and next-nearest neighbor hopping and six
critical phases with central charges being , 1 or 2 are found. We find
continuous phase transitions between and phases, while the phase
transition between and is conjectured to be of
Kosterlitz-Thouless type.Comment: published versio
Topology and Criticality in Resonating Affleck-Kennedy-Lieb-Tasaki loop Spin Liquid States
We exploit a natural Projected Entangled-Pair State (PEPS) representation for
the resonating Affleck-Kennedy-Lieb-Tasaki loop (RAL) state. By taking
advantage of PEPS-based analytical and numerical methods, we characterize the
RAL states on various two-dimensional lattices. On square and honeycomb
lattices, these states are critical since the dimer-dimer correlations decay as
a power law. On kagome lattice, the RAL state has exponentially decaying
correlation functions, supporting the scenario of a gapped spin liquid. We
provide further evidence that the RAL state on the kagome lattice is a
spin liquid, by identifying the four topological sectors and
computing the topological entropy. Furthermore, we construct a one-parameter
family of PEPS states interpolating between the RAL state and a short-range
Resonating Valence Bond state and find a critical point, consistent with the
fact that the two states belong to two different phases. We also perform a
variational study of the spin-1 kagome Heisenberg model using this
one-parameter PEPS.Comment: 10 pages, 14 figures, published versio
Investigating operations of industrial parks in Beijing: efficiency at different stages
Industrial parks enjoy significant importance in many countries
and regions. This study presents a multi-stage operational process
to evaluate the efficiency of parks at each stage using an empirical
study of Beijing. The study finds that only three of 22 parks were
efficient overall during 2006–2008 and two of 22 were efficient during
2009–2012. The promotion of business, facilitation of production, and
rewards of economic returns are highly correlated stages for efficiency
performance. The results suggest that Beijing’s government should
expend more effort developing the potential to generate outputs
given current land and investment inputs. In addition, it provides a tool
to strengthen the organisational capacity development of industrial
parks by emphasising their multi-dimensions in inputs and outputs,
selecting the right competitors at the right organisational stage,
locating sources of efficiency and inefficiency, and understanding
progression and balance of internal stages during operation
Identifiability of Label Noise Transition Matrix
The noise transition matrix plays a central role in the problem of learning
with noisy labels. Among many other reasons, a large number of existing
solutions rely on access to it. Identifying and estimating the transition
matrix without ground truth labels is a critical and challenging task. When
label noise transition depends on each instance, the problem of identifying the
instance-dependent noise transition matrix becomes substantially more
challenging. Despite recent works proposing solutions for learning from
instance-dependent noisy labels, the field lacks a unified understanding of
when such a problem remains identifiable. The goal of this paper is to
characterize the identifiability of the label noise transition matrix. Building
on Kruskal's identifiability results, we are able to show the necessity of
multiple noisy labels in identifying the noise transition matrix for the
generic case at the instance level. We further instantiate the results to
explain the successes of the state-of-the-art solutions and how additional
assumptions alleviated the requirement of multiple noisy labels. Our result
also reveals that disentangled features are helpful in the above identification
task and we provide empirical evidence.Comment: Preprint. Under review. For questions please contact [email protected]
Commercial Janus Fabrics as Reusable Facemask Materials: A Balance of Water Repellency, Filtration Efficiency, Breathability, and Reusability
Facemasks as personal protective equipment play a significant role in helping prevent the spread of viruses during the COVID-19 pandemic. A desired reusable fabric facemask should strike a balance of water repellency, good filtration efficiency (FE), breathability, and mechanical robustness against washing cycles. Despite significant efforts in testing various commercial fabric materials for filtration efficiency, few have investigated fabric performance as a function of the fiber/yarn morphology and wettability of the fabric itself. In this study, we examine commercial fabrics with Janus-like behaviors to determine the best reusable fabric facemask materials by understanding the roles of morphology, porosity, and wettability of the fabric on its overall performance. We find that the outer layer of the diaper fabric consisted of laminated polyurethane, which is hydrophobic, has low porosity (∼5%) and tightly woven yarn structures, and shows the highest overall FE (up to 54%) in the submicron particle size range (0.03-0.6 μm) among the fabrics tested. Fabric layers with higher porosity lead to lower-pressure drops, indicating higher breathability but lower FE. Tightly woven waterproof rainwear fabrics perform the best after 10 washing cycles, remaining intact morphologically with only a 2-5% drop in the overall FE in the submicron particle size range, whereas other knitted fabric layers become loosened and the laminated polyurethane thin film on the diaper fabric is wrinkled. In comparison, the surgical masks and N95 respirators made from nonwoven polypropylene (PP) fibers see over a 30% decline in the overall FE after 10 washing cycles. Overall, we find that tightly woven Janus fabrics consisting of a low porosity, a hydrophobic outer layer, and a high porosity and hydrophilic inner layer offer the best performance among the fabrics tested as they can generate a high overall FE, achieve good breathability, and maintain fabric morphology and performance over multiple washing cycles
Real-space construction of crystalline topological superconductors and insulators in 2D interacting fermionic systems
The construction and classification of crystalline symmetry protected
topological (SPT) phases in interacting bosonic and fermionic systems have been
intensively studied in the past few years. Crystalline SPT phases are not only
of conceptual importance, but also provide great opportunities towards
experimental realization since space group symmetries naturally exist for any
realistic material. In this paper, we systematically classify the crystalline
topological superconductors (TSC) and topological insulators (TI) in 2D
interacting fermionic systems by using an explicit real-space construction. In
particular, we discover an intriguing fermionic crystalline topological
superconductor that can only be realized in interacting fermionic systems
(i.e., not in free-fermion or bosonic SPT systems). Moreover, we also verify
the recently conjectured crystalline equivalence principle for generic 2D
interacting fermionic systems.Comment: 39+37 pages, 10+13 figures, 3+1 tables, all comments and suggestions
are very welcom
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