3,807 research outputs found
Geometric classification of non-Hermitian topological systems through the singularity ring
This work unveils how geometric features of two-band non-Hermitian
Hamiltonians can completely classify the topology of their eigenstates and
energy manifolds. Our approach generalizes the Bloch sphere visualization of
Hermitian systems to a ``Bloch torus'' picture for non-Hermitian systems, where
a singularity ring (SR) captures the degeneracy structure of generic
exceptional points. The SR picture affords convenient visualization of various
symmetry constraints and reduces their topological characterization to the
classification of simple intersection or winding behavior, as detailed by our
explicit study of chiral, sublattice, particle-hole and conjugated
particle-hole symmetries. In 1D, the winding number about the SR corresponds to
the band vorticity measurable through the Berry phase. In 2D, more complicated
winding behavior leads to a variety of phases that illustrate the richness of
the interplay between SR topology and geometry beyond mere Chern number
classification. Through a normalization procedure that puts generic 2-band
non-Hermitian Hamiltonians on equal footing, our SR approach also allows for
vivid visualization of the non-Hermitian skin effect.Comment: 17 pages, 15 figures, Comments are welcom
Hybrid higher-order skin-topological modes in non-reciprocal systems
Higher-order phases are characterized by corner or hinge modes that arise due
to the interesting interplay of localization mechanisms along two or more
dimensions. In this work, we introduce and construct a novel class of "hybrid"
higher-order skin-topological boundary modes in non-reciprocal systems with two
or more open boundaries. Their existence crucially relies on non-reciprocal
pumping in addition to topological localization. Unlike usual non-Hermitian
"skin" modes, they can exist in lattices with \emph{vanishing} net reciprocity
due to the selective nature of non-reciprocal pumping: While the bulk modes
remain extended due to the cancellation of non-reciprocity within each unit
cell, boundary modes experience a curious \emph{spontaneous breaking} of
reciprocity in the presence of topological localization, thereby experiencing
the non-Hermitian skin effect. The number of possible hybridization channels
increases rapidly with dimensionality, leading to a proliferation of distinct
phases. In addition, skin modes or hybrid skin-topological modes can restore
unitarity and are hence stable, allowing for experimental observations and
manipulations in non-Hermitian photonic and electrical metamaterials.Comment: 13 pages, 12 figure
Mitochondrial Cardiomyopathy Presenting as Hypertrophic Cardiomyopathy With Advanced Chronic Kidney Disease
A transverse flux permanent magnet linear generator for hybrid electric vehicles
Article: TD-007358This paper presents a transverse flux permanent magnet (TFPM) linear generator for the free-piston generation application, which not only possessing the merits of the existing TFPM machine, but also providing a simple structure which is essential for power generation with maintenance-free operation. Also, the machine configuration is optimized such that the induced voltage is maximized while the cogging force is minimized. Hence, a 2-phase linear TFPM is resulted, which is well supported by performance analysis.published_or_final_versio
AN ISOFORM-SPECIFIC ROLE OF FYNT IN ALZHEIMER'S DISEASE AND ITS RELEVANCE IN NEUROINFLAMMATION
Ph.DDOCTOR OF PHILOSOPH
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