Hybrid solid state qubits: the powerful role of electron spins

We review progress on the use of electron spins to store and process quantum information, with particular focus on the ability of the electron spin to interact with multiple quantum degrees of freedom. We examine the benefits of hybrid quantum bits (qubits) in the solid state that are based on coupling electron spins to nuclear spin, electron charge, optical photons, and superconducting qubits. These benefits include the coherent storage of qubits for times exceeding seconds, fast qubit manipulation, single qubit measurement, and scalable methods for entangling spatially separated matter-based qubits. In this way, the key strengths of different physical qubit implementations are brought together, laying the foundation for practical solid-state quantum technologies.Comment: 54 pages, 7 figure

Robust automated servicing of passenger train fluids

To meet increased capacity demands of passengers in the rail industry, a robotic and autonomous system that services the fluids on passenger rail vehicles was proposed. A hierarchical task analysis of fluid servicing processes was conducted and human and system errors were highlighted. This information, along with opinions of technical managers and staff were inputted into a quality function deployment matrix to make a design specification; from this specification two concepts were proposed. Both concepts are viable but modification to rail vehicles is required. A proof of concept will next be developed to begin a path to a commercial product.Brunel University London would like to acknowledge RSSB and RRUKA for funding this project and providing contact with key rail stakeholders

Hysteresis of Natural Magnetite Ensembles: Micromagnetics of Silicate-Hosted Magnetite Inclusions Based on Focused-Ion-Beam Nanotomography

Three-dimensional geometries of silicate-hosted magnetic inclusions from the Harcus intrusion, South Australia have been determined using focused-ion-beam nanotomography (FIB-nt). By developing an effective workflow, the geometries were reconstructed for magnetic particles in a plagioclase (162) and a pyroxene (282), respectively. For each inclusion, micromagnetic modelling using MERRILL provided averaged hysteresis loops and backfield remanence curves of 20 equidistributed field directions together with average Ms, Mrs, Hc, and Hcr . The micromagnetic structures within each silicate are single-domain, single-vortex, multi-vortex and multi-domain states. They have been analyzed using domain-state diagnostic plots, such as the Day plot and the Néel plot. SD particles can be subdivided into groups with dominant uniaxial anisotropy (Mrs/Ms ∼ 0.5 and 10 < Hc < 100 mT) and mixed uniaxial/multiaxial anisotropy (Mrs/Ms ∼ 0.7 and 10 < Hc < 30 mT). Most single-vortex particles lie on a trend with 0 < Mrs/Ms < 0.1 and 0 < Hc < 10 mT, while others dis- play a broad range of intermediate Mrs/Ms and Hc values. Single-vortex and multi-vortex states do not plot on systematic grain-size trends. Instead, the multi-component mixture of domain states within each silicate spans the entire range of natural variability seen in bulk samples. This questions the interpretation of bulk average hysteresis parameters in terms of grain size alone. FIB-nt combined with large-scale micromagnetic simulations provides a more complete characterization of silicate-hosted carriers of stable magnetic remanence. This approach will improve the understanding of single-crystal paleomagnetism, and enable primary paleomagnetic data to be extracted from ancient rocks

Life as a guide to prebiotic nucleotide synthesis

Synthesis of activated nucleotides has been accomplished under ‘prebiotically plausible’ conditions, but bears little resemblance to the chemistry of life as we know it. Here we argue that life is an indispensable guide to its own origins

Do Soluble Phosphates Direct the Formose Reaction towards Pentose Sugars?

The formose reaction has been a leading hypothesis for the prebiotic synthesis of sugars such as ribose for many decades but tends to produce complex mixtures of sugars and often tars. Channeling the formose reaction towards the synthesis of biologically useful sugars such as ribose has been a holy grail of origins-of-life research. Here, we tested the hypothesis that a simple, prebiotically plausible phosphorylating agent, acetyl phosphate, could direct the formose reaction towards ribose through phosphorylation of intermediates in a manner resembling gluconeogenesis and the pentose phosphate pathway. We did indeed find that addition of acetyl phosphate to a developing formose reaction stabilized pentoses, including ribose, such that after 5 h of reaction about 10-fold more ribose remained compared with control runs. But mechanistic analyses using liquid chromatography-mass spectrometry showed that, far from being directed towards ribose by phosphorylation, the formose reaction was halted by the precipitation of Ca2+ ions as phosphate minerals such as apatite and hydroxyapatite. Adding orthophosphate had the same effect. Phosphorylated sugars were only detected below the limit of quantification when adding acetyl phosphate. Nonetheless, our findings are not strictly negative. The sensitivity of the formose reaction to geochemically reasonable conditions, combined with the apparent stability of ribose under these conditions, serves as a valuable constraint on possible pathways of sugar synthesis at the origin of life

Rethinking how external pressure can suppress dendrites in lithium metal batteries

We offer an explanation for how dendrite growth can be inhibited when Li metal pouch cells are subjected to external loads, even for cells using soft, thin separators. We develop a contact mechanics model for tracking Li surface and sub-surface stresses where electrodes have realistically (micron-scale) rough surfaces. Existing models examine a single, micron-scale Li metal protrusion under a fixed local current density that presses more or less conformally against a separator or stiff electrolyte. At the larger, sub-mm scales studied here, contact between the Li metal and the separator is heterogeneous and far from conformal for surfaces with realistic roughness: the load is carried at just the tallest asperities, where stresses reach tens of MPa, while most of the Li surface feels no force at all. Yet, dendrite growth is suppressed over the entire Li surface. To explain this dendrite suppression, our electrochemical/mechanics model suggests that Li avoids plating at the tips of growing Li dendrites if there is sufficient local stress; that local contact stresses there may be high enough to close separator pores so that incremental Li+ ions plate elsewhere; and that creep ensures that Li protrusions are gradually flattened. These mechanisms cannot be captured by single-dendrite-scale analyses

Orangutans venture out of the rainforest and into the Anthropocene

Conservation benefits from understanding how adaptability and threat interact to determine a taxon’s vulnerability. Recognizing how interactions with humans have shaped taxa such as the critically endangered orangutan (Pongo spp.) offers insights into this relationship. Orangutans are viewed as icons of wild nature, and most efforts to prevent their extinction have focused on protecting minimally disturbed habitat, with limited success. We synthesize fossil, archeological, genetic, and behavioral evidence to demonstrate that at least 70,000 years of human influence have shaped orangutan distribution, abundance, and ecology and will likely continue to do so in the future. Our findings indicate that orangutans are vulnerable to hunting but appear flexible in response to some other human activities. This highlights the need for a multifaceted, landscape-level approach to orangutan conservation that leverages sound policy and cooperation among government, private sector, and community stakeholders to prevent hunting, mitigate human-orangutan conflict, and preserve and reconnect remaining natural forests. Broad cooperation can be encouraged through incentives and strategies that focus on the common interests and concerns of different stakeholders. Orangutans provide an illustrative example of how acknowledging the long and pervasive influence of humans can improve strategies to preserve biodiversity in the Anthropocene

Thermal-Drones as a Safe and Reliable Method for Detecting Subterranean Peat Fires

Underground peat fires are a major hazard to health and livelihoods in Indonesia, and are a major contributor to carbon emissions globally. Being subterranean, these fires can be difficult to detect and track, especially during periods of thick haze and in areas with limited accessibility. Thermal infrared detectors mounted on drones present a potential solution to detecting and managing underground fires, as they allow large areas to be surveyed quickly from above and can detect the heat transferred to the surface above a fire. We present a pilot study in which we show that underground peat fires can indeed be detected in this way. We also show that a simple temperature thresholding algorithm can be used to automatically detect them. We investigate how different thermal cameras and drone flying strategies may be used to reliably detect underground fires and survey fire-prone areas. We conclude that thermal equipped drones are potentially a very powerful tool for surveying for fires and firefighting. However, more investigation is still needed into their use in real-life fire detection and firefighting scenarios

Wider Access to Genotypic Space Facilitates Loss of Cooperation in a Bacterial Mutator

Understanding the ecological, evolutionary and genetic factors that affect the expression of cooperative behaviours is a topic of wide biological significance. On a practical level, this field of research is useful because many pathogenic microbes rely on the cooperative production of public goods (such as nutrient scavenging molecules, toxins and biofilm matrix components) in order to exploit their hosts. Understanding the evolutionary dynamics of cooperation is particularly relevant when considering long-term, chronic infections where there is significant potential for intra-host evolution. The impact of responses to non-social selection pressures on social evolution is arguably an under-examined area. In this paper, we consider how the evolution of a non-social trait – hypermutability – affects the cooperative production of iron-scavenging siderophores by the opportunistic human pathogen Pseudomonas aeruginosa. We confirm an earlier prediction that hypermutability accelerates the breakdown of cooperation due to increased sampling of genotypic space, allowing mutator lineages to generate non-cooperative genotypes with the ability to persist at high frequency and dominate populations. This may represent a novel cost of hypermutability