Poxyaibamberus Andersen & Dantas, gen. nov. (Diptera, Chironomidae, Orthocladiinae) from Brazil.

Poxyaibamberus Andersen & Dantas, gen. nov. is erected based on the males of two species, P.jamanximensis Andersen & Dantas, sp. nov. from Jamanxim National Park, Pará State, Brazil, and P.ubajarensis Andersen & Dantas, sp. nov. from Ubajara National Park, Ceará State, Brazil. Both species have a comparatively short and wide head, with large eyes and short, five-segmented palps; a strong subapical seta on the ultimate flagellomere; scalpellate acrostichals; no setae on the wing veins except for one seta on the brachiolum; a long costal extension; and a large triangular anal point and a very long heel on the gonostylus. The systematic position of the new genus is briefly discussed.

Optimizing quantum gates towards the scale of logical qubits.

A foundational assumption of quantum error correction theory is that quantum gates can be scaled to large processors without exceeding the error-threshold for fault tolerance. Two major challenges that could become fundamental roadblocks are manufacturing high-performance quantum hardware and engineering a control system that can reach its performance limits. The control challenge of scaling quantum gates from small to large processors without degrading performance often maps to non-convex, high-constraint, and time-dynamic control optimization over an exponentially expanding configuration space. Here we report on a control optimization strategy that can scalably overcome the complexity of such problems. We demonstrate it by choreographing the frequency trajectories of 68 frequency-tunable superconducting qubits to execute single- and two-qubit gates while mitigating computational errors. When combined with a comprehensive model of physical errors across our processor, the strategy suppresses physical error rates by ~3.7× compared with the case of no optimization. Furthermore, it is projected to achieve a similar performance advantage on a distance-23 surface code logical qubit with 1057 physical qubits. Our control optimization strategy solves a generic scaling challenge in a way that can be adapted to a variety of quantum operations, algorithms, and computing architectures.

A revised, annotated checklist of Mexican non-biting midges (Diptera, Chironomidae).

An updated checklist of Mexican non-biting midges (Chironomidae) is presented. A total of 110 species of Chironomidae are known for Mexico: 52 species in 25 genera belong to the subfamily Chironominae, 30 species in 13 genera to Orthocladiinae, 21 species in nine genera to Tanypodinae, five species in two genera to Telmatogetoninae, and two species in one genus to Diamesinae. In addition, 41 genera without identified species are listed. The highest number of species (29) is recorded from the state of Campeche, while 19 species have been found in Veracruz and 15 in Nuevo León. Few or no records exist for states in Central and Northern Mexico, or those on the Pacific coast. The type localities for 34 species are in Mexico; of these, 27 species (25% of the total number of species recorded in the country) are endemic. Twenty-nine species recorded in Mexico have a Neotropical distribution, 15 a Nearctic distribution, and 39 species are distributed in both the Neotropical and Nearctic regions or more widely. It has been suggested that as many as 1000 species might occur in Mexico; so only a little more than 10% of the expected diversity has so far been recorded.

Mimes of the past: Eocene midges of the tribe Pseudochironomini (Chironomidae, Diptera) reveal their peculiarities.

This is the first study focused on Eocene dipterans of the tribe Pseudochironomini (subfamily Chironominae, family Chironomidae), based on unique materials from Baltic amber. Two new genera and three new species: Eomicromimus gen. nov. with Eomicromimus polliciformis sp. nov. and Eomicromimus serpens sp. nov., and Eoriethia gen. nov. with Eoriethia ursipes sp. nov. are presented. The systematic position of the new taxa is discussed, and an amended key to the identification of adult males of extinct and extant Pseudochironomini genera is provided. The presented analysis of the morphology of the tribe's fossil members allowed us to verify the concepts regarding the origin/homology of male diagnostic structures crucial in defining new taxa, their phylogeny, and to consolidate the terminology used in chironomid research. A new habitual name for Chironomidae, "mime midges", is also proposed.

New species and records of Pseudochironomini Sæther, 1977 (Diptera, Chironomidae) from the Dominican Republic.

Background: Pseudochironomini is a relatively small and poorly-studied tribe of subfamily Chironominae (Diptera, Chironomidae). New information: Pseudochironomusruthae Andersen & Baranov sp. nov. is described and figured, based on a single male collected in a light trap at Matadero, Dominican Republic. The species can be separated from its congeners by the combination of the following characters: wing without dark bands, dorsocentrals in partly double row and apex of superior volsella rounded. The species is the first Pseudochironomus species to be formally recorded and described from the Caribbean. In addition, a new record of Manoapahayokeensis Jacobsen & Perry, 2002 from the Dominican Republic is given. One specimen was DNA-barcoded and the barcode is given.

The immature stages and female imago of Rheocricotopus (Psilocricotopus) sirventorum Andersen & Mendes, 2012, a Neotropical member of the chalybeatus species group (Diptera, Chironomidae, Orthocladiinae).

The female, larva and pupa of Rheocricotopus (Psilocricotopus) sirventorum Andersen & Mendes, 2012, are described based on specimens collected in southern Brazil. The species is the sole described species of Rheocricotopus Brundin, 1956 from the Neotropical region. The subgeneric placement is confirmed, based on the morphology of the female, larva and pupa. The species belongs in the chalybeatus species group, and a key to the pupae of the group is presented.

Beam steering at the nanosecond time scale with an atomically thin reflector.

Techniques to mold the flow of light on subwavelength scales enable fundamentally new optical systems and device applications. The realization of programmable, active optical systems with fast, tunable components is among the outstanding challenges in the field. Here, we experimentally demonstrate a few-pixel beam steering device based on electrostatic gate control of excitons in an atomically thin semiconductor with strong light-matter interactions. By combining the high reflectivity of a MoSe2 monolayer with a graphene split-gate geometry, we shape the wavefront phase profile to achieve continuously tunable beam deflection with a range of 10°, two-dimensional beam steering, and switching times down to 1.6 nanoseconds. Our approach opens the door for a new class of atomically thin optical systems, such as rapidly switchable beam arrays and quantum metasurfaces operating at their fundamental thickness limit.

A new species of Goeldichironomus Fittkau, 1965 from Argentina (Chironomidae, Chironominae).

Goeldichironomus pampeanus n. sp. is described and figured as male, pupa and larva based on reared specimens from Buenos Aires province in Argentina. The species can be separated from its congeners on the combination of the following characters: male without dark markings on thorax and an evenly curved superior volsella projecting mesad; pupa with extensive shagreen on tergites IIVI, sternites with fine shagreen only without transverse bands of points, dorsal setae on tergite IX extending beyond anal lobe and basal ring of thoracic horn kidney-shaped; larva with bifid premandible, mentum with 6 pairs of lateral teeth, anterior pair of ventral tubules simple, labral sclerite 1 intact and labral sclerite 2 consolidated on the inner side.

New species of the genus Chimarra Stephens from Africa (Trichoptera, Philopotamidae) and characterization of the African groups and subgroups of the genus.

This paper is primarily based on collections in Tanzania and Ghana in 1990-1991 and 1991-1994, respectively. In all, 46 species of Chimarra were collected, 31 of them new species. All these species are illustrated or re-illustrated and described in the paper. Additionally, five species from Africa from collections in Illinois and Minnesota, four of them new, are included. This provided the incentive to review the species of Chimarra from the African subregion and assign the majority of them to species groups and subgroups. In the process, several species were synonymized. In all 147 valid species are recognized, of which 51 are treated in this paper. Two major species groups are recognized for Africa, the marginata Group and the georgensis Group. The former is based on the type species for the genus; this is the first formal characterization of this group, as distinct from other species groups in the subgenus. Mainland African species in the marginata Group mostly fall into four large species-diverse subgroups, but a number of smaller subgroups are also recognized. Membership in these subgroups is specified for the majority of African species and characters defining the subgroups informally discussed. The georgensis Group includes a single Asian species and nine previously described African species. They are assigned to two subgroups, one newly recognized in this paper. Several additional species were considered unassigned to subgroup within the georgensis Group. The majority of the new species described in this paper belong to the georgensis Group.

Twenty years of Dipterology through the pages of Zootaxa.

We present a summary and analysis of the Diptera-related information published in Zootaxa from 2001 to 2020, with a focus on taxonomic papers. Altogether, 2,527 papers on Diptera were published, including 2,032 taxonomic papers and 1,931 papers containing new nomenclatural acts, equivalent to 22% of all publications with new nomenclatural acts for Diptera. The new nomenclatural acts include 7,431 new species, 277 new genera, 2,003 new synonymies, and 1,617 new combinations. A breakdown by family of new taxa and new replacement names proposed in the journal during the last two decades is provided, together with a comparison of Zootaxa's output to that of all other taxonomic publications on Diptera. Our results show that the journal has contributed to 20% of all biodiversity discovery in this megadiverse insect order over the last 20 years, and to about 31% in the last decade.

Neotropical Nilothauma Kieffer, 1921 (Diptera, Chironomidae): Key, eleven new species, re-descriptions, new combination and new records.

Nine new species of Nilothauma Kieffer, N. hamadae sp. nov., N. jupau sp. nov., N. karitiana sp. nov., N. leccii sp. nov., N. marianoi sp. nov., N. mateusi sp. nov., N. txukuyana sp. nov., N. werekena sp. nov. and N. yekwana sp. nov. are described and figured, based on adult males collected in Brazil and N. maya sp. nov. on an adult male from Mexico; N. terena sp. nov. is described as male, pupa and larva based on a reared specimen from Brazil. Nilothauma aleta Roback, 1960 and N. duena Roback, 1960 are re-described and recorded from Brazil. Nilothauma longissimum Mendes & Andersen, 2009 is transferred to Beardius Reiss & Sublette, 1985 and the diagnosis of Nilothauma is emended. New records of thirteen Neotropical Nilothauma species are given and a key to the males of all known species of Nilothauma is provided.

Excitons in a reconstructed moiré potential in twisted WSe2/WSe2 homobilayers.

Moiré superlattices in twisted van der Waals materials have recently emerged as a promising platform for engineering electronic and optical properties. A major obstacle to fully understanding these systems and harnessing their potential is the limited ability to correlate direct imaging of the moiré structure with optical and electronic properties. Here we develop a secondary electron microscope technique to directly image stacking domains in fully functional van der Waals heterostructure devices. After demonstrating the imaging of AB/BA and ABA/ABC domains in multilayer graphene, we employ this technique to investigate reconstructed moiré patterns in twisted WSe2/WSe2 bilayers and directly correlate the increasing moiré periodicity with the emergence of two distinct exciton species in photoluminescence measurements. These states can be tuned individually through electrostatic gating and feature different valley coherence properties. We attribute our observations to the formation of an array of two intralayer exciton species that reside in alternating locations in the superlattice, and open up new avenues to realize tunable exciton arrays in twisted van der Waals heterostructures, with applications in quantum optoelectronics and explorations of novel many-body systems.

Broken mirror symmetry in excitonic response of reconstructed domains in twisted MoSe2/MoSe2 bilayers.

Van der Waals heterostructures obtained via stacking and twisting have been used to create moiré superlattices1, enabling new optical and electronic properties in solid-state systems. Moiré lattices in twisted bilayers of transition metal dichalcogenides (TMDs) result in exciton trapping2-5, host Mott insulating and superconducting states6 and act as unique Hubbard systems7-9 whose correlated electronic states can be detected and manipulated optically. Structurally, these twisted heterostructures feature atomic reconstruction and domain formation10-14. However, due to the nanoscale size of moiré domains, the effects of atomic reconstruction on the electronic and excitonic properties have not been systematically investigated. Here we use near-0°-twist-angle MoSe2/MoSe2 bilayers with large rhombohedral AB/BA domains15 to directly probe the excitonic properties of individual domains with far-field optics. We show that this system features broken mirror/inversion symmetry, with the AB and BA domains supporting interlayer excitons with out-of-plane electric dipole moments in opposite directions. The dipole orientation of ground-state Γ-K interlayer excitons can be flipped with electric fields, while higher-energy K-K interlayer excitons undergo field-asymmetric hybridization with intralayer K-K excitons. Our study reveals the impact of crystal symmetry on TMD excitons and points to new avenues for realizing topologically non-trivial systems16,17, exotic metasurfaces18, collective excitonic phases19 and quantum emitter arrays20,21 via domain-pattern engineering.

Electrically Tunable Valley Dynamics in Twisted WSe_{2}/WSe_{2} Bilayers.

The twist degree of freedom provides a powerful new tool for engineering the electrical and optical properties of van der Waals heterostructures. Here, we show that the twist angle can be used to control the spin-valley properties of transition metal dichalcogenide bilayers by changing the momentum alignment of the valleys in the two layers. Specifically, we observe that the interlayer excitons in twisted WSe_{2}/WSe_{2} bilayers exhibit a high (>60%) degree of circular polarization (DOCP) and long valley lifetimes (>40 ns) at zero electric and magnetic fields. The valley lifetime can be tuned by more than 3 orders of magnitude via electrostatic doping, enabling switching of the DOCP from ∼80% in the n-doped regime to <5% in the p-doped regime. These results open up new avenues for tunable chiral light-matter interactions, enabling novel device schemes that exploit the valley degree of freedom.

Enhanced Photoenergy Harvesting and Extreme Thomson Effect in Hydrodynamic Electronic Systems.

The thermoelectric (TE) properties of a material are dramatically altered when electron-electron interactions become the dominant scattering mechanism. In the degenerate hydrodynamic regime, the thermal conductivity is reduced and becomes a decreasing function of the electronic temperature, due to a violation of the Wiedemann-Franz law. We here show how this peculiar temperature dependence gives rise to new striking TE phenomena. These include an 80-fold increase in TE efficiency compared to the Wiedemann-Franz regime, dramatic qualitative changes in the steady state temperature profile, and an anomalously large Thomson effect. In graphene, which we pay special attention to here, these effects are further amplified due to a doubling of the thermopower.

Electron-phonon instability in graphene revealed by global and local noise probes.

Understanding and controlling nonequilibrium electronic phenomena is an outstanding challenge in science and engineering. By electrically driving ultraclean graphene devices out of equilibrium, we observe an instability that is manifested as substantially enhanced current fluctuations and suppressed conductivity at microwave frequencies. Spatial mapping of the nonequilibrium current fluctuations using nanoscale magnetic field sensors reveals that the fluctuations grow exponentially along the direction of carrier flow. Our observations, including the dependence on density and temperature, are consistently explained by the emergence of an electron-phonon Cerenkov instability at supersonic drift velocities. These results offer the opportunity for tunable terahertz generation and active phononic devices based on two-dimensional materials.

Efficiency of Launching Highly Confined Polaritons by Infrared Light Incident on a Hyperbolic Material.

We investigated phonon-polaritons in hexagonal boron nitride-a naturally hyperbolic van der Waals material-by means of the scattering-type scanning near-field optical microscopy. Real-space nanoimages we have obtained detail how the polaritons are launched when the light incident on a thin hexagonal boron nitride slab is scattered by various intrinsic and extrinsic inhomogeneities, including sample edges, metallic nanodisks deposited on its top surface, random defects, and surface impurities. The scanned tip of the near-field microscope is itself a polariton launcher whose efficiency proves to be superior to all the other types of polariton launchers we studied. Our work may inform future development of polaritonic nanodevices as well as fundamental studies of collective modes in van der Waals materials.

A new species of Manoa Fittkau (Diptera: Chironomidae), with DNA barcodes from Xianju National Park, Oriental China.

The genus Manoa and the tribe Pseudochironomini are recorded from the Oriental region for the first time. Manoa xianjuensis Qi & Lin sp. n. from Xianju National Park, Zhejiang, China is described and illustrated as adult male and female, the latter associated with the male by standard DNA barcodes. A neighbor joining tree based on available Pseudochironomini DNA barcodes and keys to the adults in Manoa are given.

Blind Flight? A New Troglobiotic Orthoclad (Diptera, Chironomidae) from the Lukina Jama - Trojama Cave in Croatia.

The genus Troglocladius Andersen, Baranov et Hagenlund, gen. n. is erected based on T. hajdi Andersen, Baranov et Hagenlund, sp. n. collected at 980 m depth in the Lukina jama-Trojama cave system in Croatia. Morphological features such as pale color, strongly reduced eyes and very long legs make it a typical cave animal. Surprisingly, it has also retained large wings and appears to be capable of flight which would make T. hajdi the first flying troglobiont worldwide, disproving previous beliefs that bats are the only animals capable of flying in complete darkness. Morphologically the new species does not readily fit within any described genus, but shares characteristics with genera both in the tribes "Metriocnemini" and "Orthocladiini". Bayesian molecular phylogenetic analysis using the markers COI, 18S rDNAs, 28S rDNA, CADI, and CADIV groups it with the genera Tvetenia, Cardiocladius and Eukiefferiella in the tribe "Metriocnemini". Troglocladius hajdi may be parthenogenetic, as only females were collected. The discovery confirms the position of the Dinaric arch as a highly important hotspot of subterranean biodiversity.

A new invasive weed-feeding species of Polypedilum (Pentapedilum) Kieffer from South Africa (Diptera: Chironomidae, Chironominae).

Polypedilum (Pentapedilum) tuburcinatum Andersen et Bello González sp. n. is described and figured as male, female, pupa and larva based on material collected in the Eastern Cape Province in South Africa, imported into quarantine in Ireland and reared in the laboratory. The species feeds on the aquatic weed Lagarosiphon major (Ridl.) Moss ex Wager and is regarded as a promising candidate agent for biological control of this invasive weed.