4,691 research outputs found
Generalized quantization condition in topological insulator
The topological magnetoelectric effect (TME) is the fundamental quantization
effect for topological insulators in units of the fine structure constant
. In [Phys. Rev. Lett. 105, 166803(2010)], a topological quantization
condition of the TME is given under orthogonal incidence of the optical beam,
in which the wave length of the light or the thickness of the TI film must be
tuned to some commensurate values. This fine tuning is difficult to realize
experimentally. In this article, we give manifestly
covariant expressions for Kerr and Faraday angles at oblique incidence at a
topological insulator thick film. We obtain a generalized quantization
condition independent of material details, and propose a more easily realizable
optical experiment, in which only the incidence angle is tuned, to directly
measure the topological quantization associated with the TME.Comment: 3 figure
Orbitronics: the Intrinsic Orbital Hall Effect in p-Doped Silicon
The spin Hall effect depends crucially on the intrinsic spin-orbit coupling
of the energy band. Because of the smaller spin-orbit coupling in silicon, the
spin Hall effect is expected to be much reduced. We show that the electric
field in p-doped silicon can induce a dissipationless orbital current in a
fashion reminiscent of the spin Hall effect. The vertex correction due to
impurity scattering vanishes and the effect is therefore robust against
disorder. The orbital Hall effect can lead to the accumulation of local orbital
momentum at the edge of the sample, and can be detected by the Kerr effect.Comment: 4 page
Secure Quantum Secret Sharing Based on Reusable GHZ States as Secure Carriers
We show a potential eavesdropper can eavesdrop whole secret information when
the legitimate users use secure carrier to encode and decode classical
information repeatedly in the protocol [proposed in Bagherinezhad S and
Karimipour V 2003 Phys. Rev. A \textbf{67} 044302]. Then we present a revised
quantum secret sharing protocol by using Greenberger-Horne-Zeilinger state as
secure carrier. Our protocol can resist Eve's attack
Interacting topological phases and modular invariance
We discuss a (2+1) dimensional topological superconductor with left-
and right-moving Majorana edge modes and a
symmetry. In the absence of interactions, these phases are distinguished by an
integral topological invariant . With interactions, the edge state in the
case is unstable against interactions, and a invariant mass gap can be generated dynamically. We show that
this phenomenon is closely related to the modular invariance of type II
superstring theory. More generally, we show that the global gravitational
anomaly of the non-chiral Majorana edge states is the physical manifestation of
the bulk topological superconductors classified by .Comment: 11 page
Mass Spectrometry-based Methods for Phosphorylation Site Mapping of Hyperphosphorylated Proteins Applied to Net1, a Regulator of Exit from Mitosis in Yeast
Prior to anaphase in Saccharomyces cerevisiae, Cdc14 protein phosphatase is sequestered within the nucleolus and inhibited by Net1, a component of the RENT complex in budding yeast. During anaphase the RENT complex disassembles, allowing Cdc14 to migrate to the nucleus and cytoplasm where it catalyzes exit from mitosis. The mechanism of Cdc14 release appears to involve the polo-like kinase Cdc5, which is capable of promoting the dissociation of a recombinant Net1·Cdc14 complex in vitro by phosphorylation of Net1. We report here the phosphorylation site mapping of recombinant Net1 (Net1N) and a mutant Net1N allele (Net1N-19m) with 19 serines or threonines mutated to alanine. A variety of chromatographic and mass spectrometric-based strategies were used, including immobilized metal-affinity chromatography, alkaline phosphatase treatment, matrix-assisted laser-desorption post-source decay, and a multidimensional electrospray mass spectrometry-based approach. No one approach was able to identify all phosphopeptides in the tryptic digests of these proteins. Most notably, the presence of a basic residue near the phosphorylated residue significantly hampered the ability of alkaline phosphatase to hydrolyze the phosphate moiety. A major goal of research in proteomics is to identify all proteins and their interactions and post-translational modification states. The failure of any single method to identify all sites in highly phosphorylated Net1N, however, raises significant concerns about how feasible it is to map phosphorylation sites throughout the proteome using existing technologies
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