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

Further studies on the relationship between IRSL and BLSL at relatively high temperatures for potassium-feldspar from sediments

In optical dating of potassium-feldspar, the luminescence signals can be stimulated by both infrared (IR) light and blue light (BL). To develop reliable dating methods using different stimulation light sources for feldspars, it is important to understand the sources of the traps associated with the infrared stimulated luminescence (IRSL) and blue light stimulated luminescence (BLSL) and their relationship. In this study, we explored the luminescence characteristics of IRSL and BLSL at different stimulation temperatures (from 60 °C to 200 °C) and their relationship based on five sets of experiments, i.e. post-IR BLSL, post-BL IRSL experiments, pulse annealing test, dose-response test and laboratory fading rate test. Our results suggest that the luminescence characteristics of IRSL and BLSL and their relationship are dependent on stimulation temperature. For IR stimulation at a relatively high temperature of 200 °C, at least two components of IRSL signals are involved in the process. One component of IRSL signals can be easily bleached by BL stimulation at 60 °C, while the other is relatively hard to be bleached by BL stimulation at 60 °C. The two components have different luminescence properties, such as thermal stability, dose-response and laboratory fading rate

Effect of Salvia miltiorrhiza Bge extract on liver cirrhosis in rats

Purpose: To explore the effects of Salvia miltiorrhiza Bge.extract(SMBE) on diethylnitrosamine(DEN)- induced liver cirrhosis in rats.Methods: SMBE was obtained by extracting dried Salvia miltiorrhiza Bge. in water. Liver cirrhosis was induced in Wistar rats by injecting diethylnitrosamine in abdominal cavity once a week for 8 weeks. Concurrently, rats received either daily oral SMBE (SMBE group) or saline (control group). Clinical biochemical assessments, oxidative stress tests (malondialdehyde [MDA], superoxide dismutase [SOD]) were performed at 4 and 8 weeks after beginning DEN.Results: Compared to the control group, both plasma alanine transaminase (ALT, 245.6 ± 8.5 U/L) and aspartate aminotransferase (AST, 205.7 ± 5.1 U/L) were significantly lower in SMBE group after 8 weeks (p < 0.01 for both ALT and AST). SMBE group exhibited significantly lower MDA (0.41 ± 0.04 μmol/L) levels and higher SOD(0.53 ± 0.05 U/mg protein) activity than control at 8 weeks after commencing DEN (p < 0.01 for both MDA and SOD).Conclusion: SMBE has significant ameliorative effect on DEN-induced liver cirrhosis in rats. Antioxidant and anti-apoptotic effects of SMBE appear to be involved in these beneficial effects.Keywords: Salvia miltiorrhiza, Liver cirrhosis, Anti-oxidant, Anti-apoptotic, Diethylnitrosamine, Biochemical parameter