Mapping coherence in measurement via full quantum tomography of a hybrid optical detector

Quantum states and measurements exhibit wave-like --- continuous, or particle-like --- discrete, character. Hybrid discrete-continuous photonic systems are key to investigating fundamental quantum phenomena, generating superpositions of macroscopic states, and form essential resources for quantum-enhanced applications, e.g. entanglement distillation and quantum computation, as well as highly efficient optical telecommunications. Realizing the full potential of these hybrid systems requires quantum-optical measurements sensitive to complementary observables such as field quadrature amplitude and photon number. However, a thorough understanding of the practical performance of an optical detector interpolating between these two regions is absent. Here, we report the implementation of full quantum detector tomography, enabling the characterization of the simultaneous wave and photon-number sensitivities of quantum-optical detectors. This yields the largest parametrization to-date in quantum tomography experiments, requiring the development of novel theoretical tools. Our results reveal the role of coherence in quantum measurements and demonstrate the tunability of hybrid quantum-optical detectors.Comment: 7 pages, 3 figure

Avalanche Photo-Detection for High Data Rate Applications

Avalanche photo detection is commonly used in applications which require single photon sensitivity. We examine the limits of using avalanche photo diodes (APD) for characterising photon statistics at high data rates. To identify the regime of linear APD operation we employ a ps-pulsed diode laser with variable repetition rates between 0.5MHz and 80MHz. We modify the mean optical power of the coherent pulses by applying different levels of well-calibrated attenuation. The linearity at high repetition rates is limited by the APD dead time and a non-linear response arises at higher photon-numbers due to multiphoton events. Assuming Poissonian input light statistics we ascertain the effective mean photon-number of the incident light with high accuracy. Time multiplexed detectors (TMD) allow to accomplish photon- number resolution by photon chopping. This detection setup extends the linear response function to higher photon-numbers and statistical methods may be used to compensate for non-linearity. We investigated this effect, compare it to the single APD case and show the validity of the convolution treatment in the TMD data analysis.Comment: 16 pages, 5 figure

Antiphased dust deposition and productivity in the Antarctic Zone over 1.5 million years

The Southern Ocean paleoceanography provides key insights into how iron fertilization and oceanic productivity developed through Pleistocene ice-ages and their role in influencing the carbon cycle. We report a high-resolution record of dust deposition and ocean productivity for the Antarctic Zone, close to the main dust source, Patagonia. Our deep-ocean records cover the last 1.5 Ma, thus doubling that from Antarctic ice-cores. We find a 5 to 15-fold increase in dust deposition during glacials and a 2 to 5-fold increase in biogenic silica deposition, reflecting higher ocean productivity during interglacials. This antiphasing persisted throughout the last 25 glacial cycles. Dust deposition became more pronounced across the Mid-Pleistocene Transition (MPT) in the Southern Hemisphere, with an abrupt shift suggesting more severe glaciations since ~0.9 Ma. Productivity was intermediate pre-MPT, lowest during the MPT and highest since 0.4 Ma. Generally, glacials experienced extended sea-ice cover, reduced bottom-water export and Weddell Gyre dynamics, which helped lower atmospheric CO2 levels.Postprin

Detector decoy quantum key distribution

Photon number resolving detectors can enhance the performance of many practical quantum cryptographic setups. In this paper, we employ a simple method to estimate the statistics provided by such a photon number resolving detector using only a threshold detector together with a variable attenuator. This idea is similar in spirit to that of the decoy state technique, and is specially suited for those scenarios where only a few parameters of the photon number statistics of the incoming signals have to be estimated. As an illustration of the potential applicability of the method in quantum communication protocols, we use it to prove security of an entanglement based quantum key distribution scheme with an untrusted source without the need of a squash model and by solely using this extra idea. In this sense, this detector decoy method can be seen as a different conceptual approach to adapt a single photon security proof to its physical, full optical implementation. We show that in this scenario the legitimate users can now even discard the double click events from the raw key data without compromising the security of the scheme, and we present simulations on the performance of the BB84 and the 6-state quantum key distribution protocols.Comment: 27 pages, 7 figure

Connecting consumers with local produce: Insights for a local food provisioning app.

Food supply chain resilience has been challenged in recent times due to climatic, political and health (pandemic) factors. Food transportation contributes 26% of carbon emissions globally.1 Within Europe food is transported an average of 171km from farm to fork2. EU citizens waste over 58 million tonnes of food annually3 at an estimated cost of €132bn4. To address such issues, greater resilience must be built into future supply systems to reduce food waste, support the next generation of food producers with a fair income, and ensure food security for all European citizens. Utilising short food supply chains (SFSC) where ‘local’ food is sold through a limited number of intermediaries, with independent price setting for producers, and full production information available for consumers, may address these challenges. Given perceived proximity can increase the positive perception of mobile apps5, such a development could enable a SFSC that allows for dynamic food supply in local areas. This study seeks to understand consumers’ drivers and barriers in local food provisioning, and more specifically the potential for digital provisioning solutions (e.g. apps). Five focus groups were conducted across five countries (Austria, Belgium, France, Spain, UK) with a total of 35 participants. Provisioning of local and/or non-local food, and the use/non-use of digital tools were explored. A semi-inductive, thematical approach was taken for the analysis, inspired by grounded theory.6 Findings covered three key areas: 1) definitions of local food, 2) drivers and barriers to local food provisioning, and 3) drivers and barriers in food provisioning with digital tools. Firstly, exploring consumers depictions of local food led to a heterogeneous and multifactorial definition of ‘local food’. Key criteria discussed were origin, distance, type of products, number of intermediaries, packaging, type of transport, seasonality, and the context of purchase. Secondly, drivers of local food provisioning were found to be better quality (taste, freshness, healthiness), less waste/food waste, seasonality, and a reduction in the associated carbon footprint (although this was mentioned less than other drivers). Barriers to local food provisioning came in the form of expense as local food was considered more highly priced than alternatives, (although some saw this as a sacrifice to be made), lack of information (at times causing distrust) in the origin and length of the supply chain meaning consumers could not be certain it was ‘local’, and a lack of diversity. Thirdly, drivers of utilising digital tools for food provisioning were established as convenience (gaining of time, a simplified daily/weekly schedule, physical ease), along with a reduction on one’s mental load (through easily finding recipes, etc.), and finally financial drivers with consumers stating they had more control over expenses with a digital tool. Barriers to food provisioning using digital tools, were stated as a lack of variety in both products and recipes, waste associated with packaging, the proximity of other offers (such as those found in stores), and a loss of benefits such as interaction and physical presence (touch/smell, sociability) found with in-person food provisioning. This research establishes that whilst consumers may perceive some barriers to using digital tools in food provisioning, there is still potential for their use in SFSC. Future research will look to explore these results further through a larger quantitative consumer study

Ancient marine sediment DNA reveals diatom transition in Antarctica

This is the final version. Available on open access from Nature Research via the DOI in this recordData availability: The following databases were used in this study: SILVA small (version 132Ref-nr) and large (version 132Ref) subunit ribosomal RNA database (https://www.arb-silva.de/), and psbO55 (https://www.ebi.ac.uk/biostudies/studies/S-BSST659?query=S-BSST659). Detailed Supplementary Information on methods and analysis is provided with this submission. The demultiplexed raw sequencing data generated and analysed during this study have been deposited in the NCBI Sequence Read Archive database (https://www.ncbi.nlm.nih.gov/sra) under Accession code/BioProject PRJNA861836 (BioSamples SAMN29928044 - SAMN29928123)59, and includes metadata for each sediment and control sample. For further requests please contact the corresponding author. Source data are provided with this paper.Code availability: The bioinformatic pipeline used in this study was previously published in ref. 8 and additional information is provided with the Supplementary Information Notes 1–3.Antarctica is one of the most vulnerable regions to climate change on Earth and studying the past and present responses of this polar marine ecosystem to environmental change is a matter of urgency. Sedimentary ancient DNA (sedaDNA) analysis can provide such insights into past ecosystem-wide changes. Here we present authenticated (through extensive contamination control and sedaDNA damage analysis) metagenomic marine eukaryote sedaDNA from the Scotia Sea region acquired during IODP Expedition 382. We also provide a marine eukaryote sedaDNA record of ~1 Mio. years and diatom and chlorophyte sedaDNA dating back to ~540 ka (using taxonomic marker genes SSU, LSU, psbO). We find evidence of warm phases being associated with high relative diatom abundance, and a marked transition from diatoms comprising <10% of all eukaryotes prior to ~14.5 ka, to ~50% after this time, i.e., following Meltwater Pulse 1A, alongside a composition change from sea-ice to open-ocean species. Our study demonstrates that sedaDNA tools can be expanded to hundreds of thousands of years, opening the pathway to the study of ecosystem-wide marine shifts and paleo-productivity phases throughout multiple glacial-interglacial cycles.Australian and New Zealand International Ocean Discovery Program Consortium (ANZIC)University of AdelaideAustralian Research Council (ARC)Deutsche Forschungsgemeinschaft (DFG)NASANational Science Foundation (NSF)Dutch Research Council (NWO)European Union Horizon 202

Co@NH 2

We present a synthetic strategy for the efficient encapsulation of a deriv. of a well-​defined cobaloxime proton redn. catalyst within a photoresponsive metal-​org. framework (NH2- MIL-​125(Ti)​)​. The resulting hybrid system Co@MOF is demonstrated to be a robust heterogeneous composite material. Furthermore, Co@MOF is an efficient and fully recyclable noble metal-​free catalyst system for light-​driven hydrogen evolution from water under visible light illumination

Deep water inflow slowed offshore expansion of the West Antarctic Ice Sheet at the Eocene-Oligocene transition

The stability of the West Antarctic Ice Sheet is threatened by the incursion of warm Circumpolar Deepwater which flows southwards via cross-shelf troughs towards the coast there melting ice shelves. However, the onset of this oceanic forcing on the development and evolution of the West Antarctic Ice Sheet remains poorly understood. Here, we use single- and multichannel seismic reflection profiles to investigate the architecture of a sediment body on the shelf of the Amundsen Sea Embayment. We estimate the formation age of this sediment body to be around the Eocene-Oligocene Transition and find that it possesses the geometry and depositional pattern of a plastered sediment drift. We suggest this indicates a southward inflow of deep water which probably supplied heat and, thus, prevented West Antarctic Ice Sheet advance beyond the coast at this time. We conclude that the West Antarctic Ice Sheet has likely experienced a strong oceanic influence on its dynamics since its initial formation

Guidelines for diagnosis and management of the cobalamin-related remethylation disorders cblC, cblD, cblE, cblF, cblG, cblJ and MTHFR deficiency

BACKGROUND: Remethylation defects are rare inherited disorders in which impaired remethylation of homocysteine to methionine leads to accumulation of homocysteine and perturbation of numerous methylation reactions. OBJECTIVE: To summarise clinical and biochemical characteristics of these severe disorders and to provide guidelines on diagnosis and management. DATA SOURCES: Review, evaluation and discussion of the medical literature (Medline, Cochrane databases) by a panel of experts on these rare diseases following the GRADE approach. KEY RECOMMENDATIONS: We strongly recommend measuring plasma total homocysteine in any patient presenting with the combination of neurological and/or visual and/or haematological symptoms, subacute spinal cord degeneration, atypical haemolytic uraemic syndrome or unexplained vascular thrombosis. We strongly recommend to initiate treatment with parenteral hydroxocobalamin without delay in any suspected remethylation disorder; it significantly improves survival and incidence of severe complications. We strongly recommend betaine treatment in individuals with MTHFR deficiency; it improves the outcome and prevents disease when given early

Mammals [of the Sand Hills]

Of approximately 81 species of mammals present in Nebraska today, 55 occur in the Sand Hills, with an additional three species that are associated only with the Niobrara River. Nebraska as a whole is truly a crossroads for mammals because two-thirds of the species reach their distributional limits in the state (Jones, 1964). Most of these mammals are widespread species or are specific to the grasslands as a whole and are not affected by this sandy zone. Jones (1964) wrote that “only a few mammals are restricted to this area. Mostly it serves to filter western species moving east and, in part, eastern species moving west, although some of the latter have passed through the area along the riparian [river] community bordering the Platte River.” On the other hand, the Sand Hills appear to be a barrier to the distribution of some mammals. The eastern woodrat is a southern species that during a warmer, wetter time moved north. Today an isolated population occurs only along the Niobrara River in central Nebraska. Another mammal, the olive-backed pocket mouse, is found north of the Niobrara River in Cherry County and in the Panhandle, but evidently it does not inhabit the Sand Hills. The Sand Hills, with their extraordinary variety of habitats from dune top to interdunal wetland and river bank, provide habitats for many different types of mammals. The drier upland Sand Hills have an abundance of plains pocket gophers, plains pocket mice, Ord’s kangaroo rats, prairie voles, and deer mice. Wet areas are characterized by the masked shrew, jumping mouse, meadow vole, and muskrat. The open areas, such as ridge tops and blowouts, tend to be the best microhabitat for kangaroo rats, which are bipedal and fast-moving; the dense grass microhabitat is favored by voles, which are quadrapedal and slow moving. Typically, kangaroo rats are from western, drier habitats, and voles are from eastern, moister habitats. In the Sand Hills, however, these two mammals occur together because of the mosaic of sand and grass (Lemen and Freeman, 1986). Marsupials: Opossum (Didelphis virginiana) Insectivores: Masked shrew (Sorex cinereus); Short-tailed shrew (Blarina brevicauda); Least shrew (Cryptotis parva); Eastern mole (Scalopus aquaticus) Bats: Keen\u27s bat (Myotis keeni); Small-footed bat (Myotis leibi); Silver-haired bat (Lasionycteris noctivagans); Big brown bat (Eptesicus fuscus); Red bat (Lasiurus borealis); Hoary bat (Lasiurus cinereus); *Brazilian free-tailed bat (Tadarida brasiliensis) Rabbits: Desert cottontail (Sylvilagus auduboni); Eastern cottontail (Sylvilagus floridanus); Black-tailed jackrabbit (Lepus californicus); White-tailed jackrabbit (Lepus townsendi) Rodents: Franklin\u27s ground squirrel (Spermophilus franklini); Spotted ground squirrel (Spermophilus spilosoma); Thirteen-lined ground squirrel (Spermophilus tridecemlineatus); Black-tailed prairie dog (Cynomys ludovicianus); Fox squirrel (Sciurus niger); Plains pocket gopher (Geomys bursarius); Plains pocket mouse (Perognathus flavescens); Silky pocket mouse (Perognathus flavus); Hispid pocket mouse (Perognathus hispidus); Ord\u27s kangaroo rat (Dipodomys ordi); Beaver (Castor canadensis); Western harvest mouse (Reithrodontomys megalotis); Plains harvest mouse (Reithrodontomys montanus); White-footed mouse (Peromyscus leucopus); Deer mouse (Peromyscus maniculatus); Northern grasshopper mouse (Onychomys leucogaster); Eastem woodrat (Neotoma floridana); Southem bog lemming (Synaptomys cooperi); Prairie vole (Microtus ochrogaster); Meadow vole (Microtus pennsylvanicus); Muskrat (Ondatra zibethicus); Meadow jumping mouse (Zapus hudsonius); Porcupine (Erethizon dorsatum); House mouse (Mus musculus); Norway rat (Rattus norvegicus) Carnivores: Coyote (Canis latrans); Swift fox (Vulpes velox); Red fox (Vulpes vulpes); Gray fox (Urocyon cinereoargenteus); Raccoon (Procyon lotor); Long-tailed weasel (Mustela frenata); Least weasel (Mustela nivalis); Mink (Mustela vison); Badger (Taxidea taxus); Spotted skunk (Spilogale putorius); Striped skunk (Mephitis mephitis); Bobcat (Lynx rufus) Artiodactyls: Elk (Cervus canadensis); Mule deer (Odocoileus hemionus); White-tailed deer (Odocoileus virginianus); Pronghom (Antilocapra americana); Bison (Bison bison