"Smoking gun" signatures of topological milestones in trivial materials by measurement fine-tuning and data postselection

Exploring the topology of electronic bands is a way to realize new states of matter with possible implications for information technology. Because bands cannot always be observed directly, a central question is how to tell that a topological regime has been achieved. Experiments are often guided by a prediction of a unique signal or a pattern, called "the smoking gun". Examples include peaks in conductivity, microwave resonances, and shifts in interference fringes. However, many condensed matter experiments are performed on relatively small, micron or nanometer-scale, specimens. These structures are in the so-called mesoscopic regime, between atomic and macroscopic physics, where phenomenology is particularly rich. In this paper, we demonstrate that the trivial effects of quantum confinement, quantum interference and charge dynamics in nanostructures can reproduce accepted smoking gun signatures of triplet supercurrents, Majorana modes, topological Josephson junctions and fractionalized particles. The examples we use correspond to milestones of topological quantum computing: qubit spectroscopy, fusion and braiding. None of the samples we use are in the topological regime. The smoking gun patterns are achieved by fine-tuning during data acquisition and by subsequent data selection to pick non-representative examples out of a fluid multitude of similar patterns that do not generally fit the "smoking gun" designation. Building on this insight, we discuss ways that experimentalists can rigorously delineate between topological and non-topological effects, and the effects of fine-tuning by deeper analysis of larger volumes of data.Comment: Data are available through Zenodo at DOI: 10.5281/zenodo.834930

Differences Found in the Macroinvertebrate Community Composition in the Presence or Absence of the Invasive Alien Crayfish, Orconectes hylas.

Introductions of alien species into aquatic ecosystems have been well documented, including invasions of crayfish species; however, little is known about the effects of these introductions on macroinvertebrate communities. The woodland crayfish (Orconectes hylas (Faxon)) has been introduced into the St. Francis River watershed in southeast Missouri and has displaced populations of native crayfish. The effects of O. hylas on macroinvertebrate community composition were investigated in a fourth-order Ozark stream at two locations, one with the presence of O. hylas and one without. Significant differences between sites and across four sampling periods and two habitats were found in five categories of benthic macroinvertebrate metrics: species richness, percent/composition, dominance/diversity, functional feeding groups, and biotic indices. In most seasons and habitat combinations, the invaded site had significantly higher relative abundance of riffle beetles (Coleoptera: Elmidae), and significantly lower Missouri biotic index values, total taxa richness, and both richness and relative abundance of midges (Diptera: Chironomidae). Overall study results indicate that some macroinvertebrate community differences due to the O. hylas invasion were not consistent between seasons and habitats, suggesting that further research on spatial and temporal habitat use and feeding ecology of Ozark crayfish species is needed to improve our understanding of the effects of these invasions on aquatic communities

List of macroinvertebrate metrics, references, abbreviations, metric categories and predicted responses to increasing perturbation at biological sampling sites in 2011 at Crane Pond Creek, Iron County, Missouri, USA.

<p>List of macroinvertebrate metrics, references, abbreviations, metric categories and predicted responses to increasing perturbation at biological sampling sites in 2011 at Crane Pond Creek, Iron County, Missouri, USA.</p

Statistical significance (Pr > F values) for interaction terms from analysis of site differences in metric values (non-parametric nested ANOVA, α = 0.05) for Crane Pond Creek, Iron County, Missouri, USA.

<p>Macroinvertebrates sampled in two habitats during four time periods in 2011. Metric abbreviations are given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150199#pone.0150199.t001" target="_blank">Table 1</a>. NS = not significant, P = Sampling Period (season), H = Habitat, S = Site.</p

Missouri Biotic Index of macroinvertebrate communities sampled during four periods in two habitats at Crane Pond Creek, Iron County, Missouri, USA in 2011.

<p>Bars represent mean and range of n = 3 samples, with ± 1 S.E. Habitats: CS = coarse substrate, NF = non-flow, HP = both habitats pooled. * = significant differences detected between sites.</p

Statistical significance (Pr> │+│from ANOVA, α = 0.05) in macroinvertebrate metrics between Site 1 (invaded) and Site 2 (control) in two habitats sampled from Crane Pond Creek, Iron County, Missouri, USA in Late Summer 2011.

<p>Metric abbreviations are defined in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150199#pone.0150199.t001" target="_blank">Table 1</a>. NS = Not Significant.</p

Percent (%) Chironomidae of macroinvertebrate communities sampled during four periods in two habitats at Crane Pond Creek, Iron County, Missouri, USA in 2011.

<p>Bars represent mean and range of n = 3 samples, with ± 1 S.E. Habitats: CS = coarse substrate, NF = non-flow, HP = both habitats pooled. * = significant differences detected between sites.</p

Sampling locations on Crane Pond Creek, Iron County, Missouri, USA in 2011.

<p>Sampling locations on Crane Pond Creek, Iron County, Missouri, USA in 2011.</p