Characterization of four-qubit states via Bell inequalities

A set of Bell inequalities classifying the quantum entanglement of four-qubit states is presented. These inequalities involve only two measurement settings per observer and can characterize fully separable, bi-separable and tri-separable quantum states. In addition, a quadratic inequality of the Bell operators for four-qubit systems is derived

Dislocation Majorana Bound States in Iron-based Superconductors

We show that lattice dislocations of topological iron-based superconductors such as FeTe$_{1-x}$Se$_x$ will intrinsically trap non-Abelian Majorana quasiparticles, in the absence of any external magnetic field. Our theory is motivated by the recent experimental observations of normal-state topology and surface magnetism that coexist with superconductivity in FeTe$_{1-x}$Se$_x$, the combination of which naturally evokes an emergent second-order topological superconductivity in a two-dimensional subsystem spanned by screw or edge dislocations. This exemplifies a new embedded higher-order topological phase in class D, where Majorana zero modes appear around the "corners" of a low-dimensional embedded subsystem, instead of those of the full crystal. A nested domain wall theory is developed to understand the origin of these defect Majorana zero modes. When the surface magnetism is absent, we further find that $s_{\pm}$ pairing symmetry itself is capable of inducing a different type of class-DIII embedded higher-order topology with defect-bound Majorana Kramers pairs. We also provide detailed discussions on the real-world material candidates for our proposals, including FeTe$_{1-x}$Se$_x$, LiFeAs, $\beta$-PdBi$_2$, and heterostructures of bismuth, etc. Our work establishes lattice defects as a new venue to achieve high-temperature topological quantum information processing.Comment: 12 pages, 5 figure

Triptolide induces cell apoptosis in human stomach cancer cell via caspase 3-dependent cascade pathway

Purpose: To evaluate the effect of triptolide on the induction of cell apoptosis in human gastric cancer BGC-823 cells.Methods: The cytotoxicity of triptolide was evaluated by 3-(4, 5-dimethylthiazol-2-yl)-2, 5- diphenyltetrazolium bromide (MTT) assay. The effect of triptolide on cell proliferation was measured using lactate dehydrogenase (LDH) assay. Cell apoptosis was determined by Annexin V/propidium iodide (PI) double-staining assay.Results: MTT results indicate that triptolide significantly decreased cancer cell numbers in dose- and time-dependent manners in MTT assay. Data from LDH assay showed that triptolide markedly induced cytotoxicity in gastric cancer cells. Triptolide also remarkably induced both early and late apoptotic process in BGC-823 cells. In addition, the compound down-regulated the expression of anti-apoptotic Bcell lymphoma-2 (bcl-2) and up-regulated the expression of pro-apoptotic BCL-2-associated X (bax) in a dose-dependent manner. Furthermore, the pro-apoptotic activity of triptolide was involved in the activation of caspase-3 pathway in BGC-823 cells.Conclusion: Taken together, the findings strongly indicates that the pro-apoptotic activity of triptolide is regulated by caspase 3-dependent cascade pathway, and thus needs to be further developed for cancer therapy.Keywords: Triptolide, Gastric cancer therapy, Apoptosis, Cytotoxicity, Caspas