Nonlocality of Majorana modes in hybrid nanowires

Spatial separation of Majorana zero modes distinguishes trivial from topological midgap states and is key to topological protection in quantum computing applications. Although signatures of Majorana zero modes in tunneling spectroscopy have been reported in numerous studies, a quantitative measure of the degree of separation, or nonlocality, of the emergent zero modes has not been reported. Here, we present results of an experimental study of nonlocality of emergent zero modes in superconductor-semiconductor hybrid nanowire devices. The approach takes advantage of recent theory showing that nonlocality can be measured from splitting due to hybridization of the zero mode in resonance with a quantum dot state at one end of the nanowire. From these splittings as well as anticrossing of the dot states, measured for even and odd occupied quantum dot states, we extract both the degree of nonlocality of the emergent zero mode, as well as the spin canting angles of the nonlocal zero mode. Depending on the device measured, we obtain either a moderate degree of nonlocality, suggesting a partially separated Andreev subgap state, or a highly nonlocal state consistent with a well-developed Majorana modeThis research was supported by Microsoft, the Danish National Research Foundation, the European Commission, and the Spanish Ministry of Economy and Competitiveness through Grants No. FIS2015-65706-P, No. FIS2015-64654-P, and No. FIS2016-80434-P (AEI/FEDER, EU), the Ramón y Cajal programme Grant No. RYC-2011-09345, and the María de Maeztu Programme for Units of Excellence in R&D (Grant No. MDM-2014-0377). C.M.M. acknowledges support from the Villum Foundation. M.-T.D. acknowledges support from State Key Laboratory of High Performance Computing, Chin

Theory of Caroli-de Gennes-Matricon analogs in full-shell nanowires

Full-shell nanowires are hybrid nanostructures consisting of a semiconducting core encapsulated in an epitaxial superconducting shell. When subject to an external magnetic flux, they exhibit the Little-Parks (LP) phenomenon of flux-modulated superconductivity, an effect connected to the physics of Abrikosov vortex lines in type-II superconductors. We show that full-shell nanowires can host subgap states that are a variant of the Caroli-de Gennes-Matricon (CdGM) states in vortices. These CdGM analogs are in fact shell-induced Van Hove singularities in propagating core subbands. We elucidate their structure, parameter dependence and behavior in tunneling spectroscopy through a series of models of growing complexity. We show through microscopic numerical simulations that they exhibit a characteristic skewness towards high magnetic fields inside non-zero LP lobes resulting from the interplay of three ingredients. First, core subbands exhibit a diamagnetic response, so that they disperse with flux depending on their generalized angular momentum. Second, the band bending at the core/shell interface induces a ring-like profile on the CdGM analog state wavefunctions with average radius smaller than the core radius. And last, degeneracy points emerge where all the CdGM Van Hove singularities coalesce. This happens when the flux threading each wavefunction is equal to an integer multiple of the flux quantum, a condition that shifts the degeneracy points away from the center of the LP lobes, skewing the CdGM analogs. Our analysis unlocks a transparent analytical description that allows to extract precise microscopic information about the nanowire by measuring the energy and skewness of CdGM analogs.Comment: 15 pages, 9 figure

Pensamiento crítico para el Pensamiento gráfico

PASSMORE (1967) define el Pensamiento Crítico como un proceso que es a la vez reflexivo e imaginativo, cualidades imprescindibles en todo proceso de diseño. En este artículo nos centramos en la utilización del Pensamiento Crítico para mejorar lo que se ha dado en llamar Pensamiento Gráfico. El trabajo se divide en dos partes complementarias. En la primera, se formula un marco teórico en torno a los conceptos de Pensamiento Crítico y Pensamiento Gráfico, para proponer una metodología de enseñanza de la ingeniería que relacione ambos conceptos. En la segunda, se aplican dichos aspectos al estudio de una herramienta esencial dentro del proceso de diseño, el diagrama, y a la manera de proyectar en la contemporaneidad. - Critical thinking is defined by PASSMORE (1967) as a process that is both reflexive and imaginative, essencial aspects of the design process. This paper focuses on the use of Critical Thinking to improve what we call Graphic Thinking. The content is two fold. The first part establishes a theoretical framework around the concepts of Critical Thinking and Graphic Thinking, in order to propose a methodology for engineering education through the combination of both concepts. The second one deals with those concepts, which are applied to one of the basic tools within the design process, the diagram, analysing through it the contemporary way of designing

Effect of the MC1R gene on sexual dimorphism in melanin-based colorations.

Variants of the melanocortin-1 receptor (MC1R) gene result in abrupt, naturally selected colour morphs. These genetic variants may differentially affect sexual dimorphism if one morph is naturally selected in the two sexes but another morph is naturally or sexually selected only in one of the two sexes (e.g. to confer camouflage in reproductive females or confer mating advantage in males). Therefore, the balance between natural and sexual selections can differ between MC1R variants, as suggest studies showing interspecific correlations between sexual dimorphism and the rate of nonsynonymous vs. synonymous amino acid substitutions at the MC1R. Surprisingly, how MC1R is related to within-species sexual dimorphism, and thereby to sex-specific selection, has not yet been investigated. We tackled this issue in the barn owl (Tyto alba), a species showing pronounced variation in the degree of reddish pheomelanin-based coloration and in the number and size of black feather spots. We found that a valine (V)-to-isoleucine (I) substitution at position 126 explains up to 30% of the variation in the three melanin-based colour traits and in feather melanin content. Interestingly, MC1R genotypes also differed in the degree of sexual colour dimorphism, with individuals homozygous for the II MC1R variant being 2 times redder and 2.5 times less sexually dimorphic than homozygous individuals for the VV MC1R variant. These findings support that MC1R interacts with the expression of sexual dimorphism and suggest that a gene with major phenotypic effects and weakly influenced by variation in body condition can participate in sex-specific selection processes

Mutational screening of splicing factor genes in cases with autosomal dominant retinitis pigmentosa.

PURPOSE: Mutations in genes encoding proteins from the tri-snRNP complex of the spliceosome account for more than 12% of cases of autosomal dominant retinitis pigmentosa (adRP). Although the exact mechanism by which splicing factor defects trigger photoreceptor death is not completely clear, their role in retinitis pigmentosa has been demonstrated by several genetic and functional studies. To test for possible novel associations between splicing factors and adRP, we screened four tri-snRNP splicing factor genes (EFTUD2, PRPF4, NHP2L1, and AAR2) as candidate disease genes. METHODS: We screened up to 303 patients with adRP from Europe and North America who did not carry known RP mutations. Exon-PCR and Sanger methods were used to sequence the NHP2L1 and AAR2 genes, while the sequences of EFTUD2 and PRPF4 were obtained by using long-range PCRs spanning coding and non-coding regions followed by next-generation sequencing. RESULTS: We detected novel missense changes in individual patients in the sequence of the genes PRPF4 and EFTUD2, but the role of these changes in relationship to disease could not be verified. In one other patient we identified a novel nucleotide substitution in the 5' untranslated region (UTR) of NHP2L1, which did not segregate with the disease in the family. CONCLUSIONS: The absence of clearly pathogenic mutations in the candidate genes screened in our cohort suggests that EFTUD2, PRPF4, NHP2L1, and AAR2 are either not involved in adRP or are associated with the disease in rare instances, at least as observed in this study in patients of European and North American origin

Molecular evolution of the proopiomelanocortin system in Barn owl species.

Examination of genetic polymorphisms in outbred wild-living species provides insights into the evolution of complex systems. In higher vertebrates, the proopiomelanocortin (POMC) precursor gives rise to α-, β-, and γ-melanocyte-stimulating hormones (MSH), which are involved in numerous physiological aspects. Genetic defects in POMC are linked to metabolic disorders in humans and animals. In the present study, we undertook an evolutionary genetic approach complemented with biochemistry to investigate the functional consequences of genetic polymorphisms in the POMC system of free-living outbred barn owl species (family Tytonidae) at the molecular level. Our phylogenetic studies revealed a striking correlation between a loss-of-function H9P mutation in the β-MSH receptor-binding motif and an extension of a poly-serine stretch in γ3-MSH to ≥7 residues that arose in the barn owl group 6-8 MYA ago. We found that extension of the poly-serine stretches in the γ-MSH locus affects POMC precursor processing, increasing γ3-MSH production at the expense of γ2-MSH and resulting in an overall reduction of γ-MSH signaling, which may be part of a negative feedback mechanism. Extension of the γ3-MSH poly-serine stretches ≥7 further markedly increases peptide hormone stability in plasma, which is conserved in humans, and is likely relevant to its endocrine function. In sum, our phylogenetic analysis of POMC in wild living owls uncovered a H9P β-MSH mutation subsequent to serine extension in γ3-MSH to 7 residues, which was then followed by further serine extension. The linked MSH mutations highlight the genetic plasticity enabled by the modular design of the POMC gene

Current-voltage correlations in interferometers

We investigate correlations of current at contacts and voltage fluctuations at voltage probes coupled to interferometers. The results are compared with correlations of current and occupation number fluctuations at dephasing probes. We use a quantum Langevin approach for the average quantities and their fluctuations. For higher order correlations we develop a stochastic path integral approach and find the generating functions of voltage or occupation number fluctuations. We also derive a generating function for the joint distribution of voltage or occupation number at the probe and current fluctuations at a terminal of a conductor. For energy independent scattering we found earlier that the generating function of current cumulants in interferometers with a one-channel dephasing or voltage probe are identical. Nevertheless, the distribution function for voltage and the distribution function for occupation number fluctuations differ, the latter being broader than that of former in all examples considered here.Comment: 23 pages, 10 figures, minor changes, additional appendix, added reference

On the Effects of N-P-K Fertilizer to the Electricity Generated by Aloe barbadensis miller

Nowadays, electricity is a pressing conflict due to the increase in demand by the populace. Thus, energy prices have also increased, making it considerably inaccessible to several population members. Considering this, the researchers have studied the type of N-PK fertilizer that can improve the efficiency of producing electricity from a living plant. There were four experimental setups of Aloe barbadensis miller that were utilized in the experiment. Every variable and component of each setup was constant, except the type of fertilizer that was added to the soil. The first setup did not have any fertilizer, the second group had Nitrogen-based (N-P-K 21:0:0), the third group had Phosphorus-based (N-P-K 0:22:0), and the fourth group had Potassium-based (N-P-K 0:0:50). The researchers gathered data on electricity generated in the Aloe vera derived from a capacitor using a multimeter every 12 hours for 16 days. Descriptive statistics and repeated measures of ANOVA statistical tests were utilized to perform the data analysis. Results showed that the setup with potassium-based fertilizer had produced significantly greater electricity (p \u3c .05) among the four setups whose differences were insignificant (p \u3e .05). Time had a moderate but negligible effect on the electricity produced by the Aloe vera. It is advised to increase the time taken to observe the plant if further research will be done on the topic

Herschel-HIFI observations of high-J CO and isotopologues in star-forming regions:from low to high mass

Context. Our understanding of the star formation process has traditionally been confined to certain mass or luminosity boundaries because most studies focus only on low-, intermediate-, or high-mass star-forming regions. Therefore, the processes that regulate the formation of these different objects have not been effectively linked. As part of the "Water In Star-forming regions with Herschel" (WISH) key programme, water and other important molecules, such as CO and OH, have been observed in 51 embedded young stellar objects (YSOs). The studied sample covers a range of luminosities from 10(5) L-circle dot.Aims. We analyse the CO line emission towards a large sample of embedded protostars in terms of both line intensities and profiles. This analysis covers a wide luminosity range in order to achieve better understanding of star formation without imposing luminosity boundaries. In particular, this paper aims to constrain the dynamics of the environment in which YSOs form.Methods. Herschel-HIFI spectra of the (CO)-C-12 J = 10-9, (CO)-C-13 J = 10-9 and (CO)-O-18 J = 5-4, J = 9-8 and J = 10-9 lines were analysed for a sample of 51 embedded protostars. In addition, JCMT spectra of (CO)-C-12 J = 3-2 and (CO)-O-18 J = 3-2 extend this analysis to cooler gas components. We focussed on characterising the shape and intensity of the CO emission line profiles by fitting the lines with one or two Gaussian profiles. We compared the values and results of these fits across the entire luminosity range covered by WISH observations. The effects of different physical parameters as a function of luminosity and the dynamics of the envelope-outflow system were investigated.Results. All observed CO and isotopologue spectra show a strong linear correlation between the logarithms of the line and bolometric luminosities across six orders of magnitude on both axes. This suggests that the high-J CO lines primarily trace the amount of dense gas associated with YSOs and that this relation can be extended to larger (extragalactic) scales. The majority of the detected (CO)-C-12 line profiles can be decomposed into a broad and a narrow Gaussian component, while the (CO)-O-18 spectra are mainly fitted with a single Gaussian. For low-and intermediate-mass protostars, the width of the (CO)-O-18 J = 9-8 line is roughly twice that of the (CO)-O-18 J = 3-2 line, suggesting increased turbulence/infall in the warmer inner envelope. For high-mass protostars, the line widths are comparable for lower-and higher-J lines. A broadening of the line profile is also observed from pre-stellar cores to embedded protostars, which is due mostly to non-thermal motions (turbulence/infall). The widths of the broad (CO)-C-12 J = 3-2 and J = 10-9 velocity components correlate with those of the narrow (CO)-O-18 J = 9-8 profiles, suggesting that the entrained outflowing gas and envelope motions are related but independent of the mass of the protostar. These results indicate that physical processes in protostellar envelopes have similar characteristics across the studied luminosity range.</p