Dynamical decoupling of spin ensembles with strong anisotropic interactions

Ensembles of dopants have widespread applications in quantum technology. The miniaturization of corresponding devices is however hampered by dipolar interactions that reduce the coherence at increased dopant density. We theoretically and experimentally investigate this limitation. We find that dynamical decoupling can alleviate, but not fully eliminate, the decoherence in crystals with strong anisotropic spin-spin interactions. Our findings can be generalized to all quantum systems with anisotropic g-factor used for quantum sensing, microwave-to-optical conversion, and quantum memory.Comment: Second version of the manuscript contains additional measurements, in which dynamical decoupling in the absence of strong spin-spin interactions is demonstrate

The world's northern most harbour seal population - How many are there?

This study presents the first abundance estimate for the world's northernmost harbour seal (Phoca vitulina) population, which resides in Svalbard, Norway, based on three digital stereoscopic photographic surveys conducted in 2009 and 2010. The counts from these high resolution 3D images were combined with a novel method for estimating correction factors for animals that were in the water at the time of the surveys, in which extensive behavioural data from radio-tagged harbour seals were used together with a modelled stationary age structure to estimate the proportion of seals of various age and sex classes hauled out at the times of the surveys. To detect possible seasonal shifts in age distribution between surveys, lengths of hauled out seals were measured from the stereoscopic images. No such length differences were detected; but, this may be due to a high degree of sexual dimorphism exhibited in this population. Applying the modelled correction factors, a total of 1888 (95 % CI: 1660-3023), 1742 (1381-3549) and 1812 (1656-4418) harbour seals were estimated for the surveys flown on 01 August 2009, 01 August 2010 and 19 August 2010, respectively.The similarity between the three survey estimates (despite significant differences in the number of animals actually counted on the photos from each survey effort) suggests that the variation in numbers of hauled out seals is reasonably accurately adjusted for by the correction factor model. The low population size, the limited spatial distribution of the population and its reduced genetic diversity make it vulnerable to stochastic mortality events. However, barring disease events, climate change—a major threat to many arctic marine mammals—is likely to have a positive impact on this population as more suitable habitat becomes available and competition from endemic arctic pinnipeds is reduced

Erbium dopants in silicon nanophotonic waveguides

The combination of established nanofabrication with attractive material properties makes silicon a promising material for quantum technologies, where implanted dopants serve as qubits with high density and excellent coherence even at elevated temperatures. In order to connect and control these qubits, interfacing them with light in nanophotonic waveguides offers unique promise. Here, we present resonant spectroscopy of implanted erbium dopants in such waveguides. We overcome the requirement of high doping and above-bandgap excitation that limited earlier studies. We thus observe erbium incorporation at well-defined lattice sites with a thousandfold reduced inhomogeneous broadening of about 1 GHz and a spectral diffusion linewidth down to 45 MHz. Our study thus introduces a novel materials platform for the implementation of on-chip quantum memories, microwave-to-optical conversion, and distributed quantum information processing, with the unique feature of operation in the main wavelength band of fiber-optic communication.Comment: 7 pages, 4 figure

Laser stabilization to a cryogenic fiber ring resonator

The frequency stability of lasers is limited by thermal noise in state-of-the-art frequency references. Further improvement requires operation at cryogenic temperature. In this context, we investigate a fiber-based ring resonator. Our system exhibits a first-order temperature-insensitive point around $3.55$ K, much lower than that of crystalline silicon. The observed low sensitivity with respect to vibrations ($<5\cdot{10^{-11}}\,\text{m}^{-1} \text{s}^{2}$), temperature ($-22(1)\cdot{10^{-9}}\,\text{K}^{-2}$) and pressure changes ($4.2(2)\cdot{10^{-11}}\,\text{mbar}^{-2}$) makes our approach promising for future precision experiments

The relationship between pressure drop and liquid saturation in oil-mist filters - Predicting filter saturation using a capillary based model

This work details the results of a study into the relationship between pressure drop and liquid saturation in mist (or coalescing) filters. Liquid saturation (clogging) in mist filters is of critical importance as it is directly related to filter efficiency and flow resistance. Experiments were conducted to determine steady-state saturation and pressure drop values in commonly used oleophillic fibrous filter media, using a range of different combinations of face velocity and number of layers of media within the filter element. Several empirical relationships for saturation and pressure drop were derived based on the relationships found. In addition, a capillary-based saturation model has been described and fitted to the experimental data. A good agreement between the model and data was obtained when an empirically fitted term was added. Equations were developed which allow such variables to be determined from known parameters

Governance of Digital Health Data on Cooperatively Organized Platforms – a Design Thinking Approach

More and more stakeholders are collecting data for improving their services: from scientific research over public administration to commercial enterprises. Existing data management services offer few rights of co-determination for their users. Data cooperatives aim to provide a democratic alternative to this. Through such a platform cooperative members are supposed to be enabled to share their data in a self-determined way. In this paper, we present a design thinking-based user research with stakeholders of data cooperatives in a health-data context. We provide an overview of motivations, expectations, and interfaces between a cooperative and individuals as cooperative members, organizations, representatives from research, and policy makers. In an iterative process, 34 interviews were conducted with different stakeholder groups, from which 7 personas were subsequently derived. For these, 4 prototypes were developed and tested with potential users. Our results show that all interviewed groups were very interested in the concept of data cooperatives. At the same time, it proves challenging to reconcile the conflicting internal and external requirements and to implement attractive value propositions for all stakeholders

Sensitivity of process signals to deviations in material distribution and material properties of hybrid workpieces

Hybrid components, made of multiple materials, can meet the increasing demands for lightweight construction and functional integration in the automotive and aircraft industry. Hybrid semi-finished components are produced by applying a high-alloy cladding to a low-alloy base material before hot-forming and machining the workpiece. Throughout this process chain, workpiece deviations in the form of material distribution and material properties can occur that influence the component’s lifetime. This paper investigates whether such workpiece deviations can be detected within the process chain by analyzing process signals obtained from subsequent process steps. For this purpose, artificial workpiece deviations were introduced to hybrid semi-finished workpieces made of C22.8/X45CrSi9-3. Then, process signals during forming and machining were analyzed to determine their sensitivity to the artificial deviations. The results revealed that deviations in cladding size can be effectively monitored using signals from both forming and machining. Cladding position deviations can only be detected during machining, while forming signals are more responsive to detecting the introduced hardness deviations of approx. 100 HV0.1

Yaws Disease Caused by Treponema pallidum subspecies pertenue in Wild Chimpanzee, Guinea, 2019

Yaws-like lesions are widely reported in wild African great apes, yet the causative agent has not been confirmed in affected animals. We describe yaws-like lesions in a wild chimpanzee in Guinea for which we demonstrate infection with Treponema pallidum subsp. pertenue. Assessing the conservation implications of this pathogen requires further research

Encoding a magic state with beyond break-even fidelity

We distill magic states to complete a universal set of fault-tolerant logic gates that is needed for large-scale quantum computing. By encoding better quality input states for our distillation procedure, we can reduce the considerable resource cost of producing magic states. We demonstrate an error-suppressed encoding scheme for a two-qubit input magic state, that we call the CZ state, on an array of superconducting qubits. Using a complete set of projective logical Pauli measurements, that are also tolerant to a single circuit error, we propose a circuit that demonstrates a magic state prepared with infidelity $(1.87 \pm 0.16) \times 10^{-2}$. Additionally, the yield of our scheme increases with the use of adaptive circuit elements that are conditioned in real time on mid-circuit measurement outcomes. We find our results are consistent with variations of the experiment, including where we use only post-selection in place of adaptive circuits, and where we interrogate our output state using quantum state tomography on the data qubits of the code. Remarkably, the error-suppressed preparation experiment demonstrates a fidelity exceeding that of the preparation of the same unencoded magic-state on any single pair of physical qubits on the same device.Comment: 10 pages, 7 figures, comments welcom

Needle Knife-assisted Endoscopic Polypectomy for a Large Inflammatory Fibroid Colon Polyp by Making Its Stalk into an Omega Shape Using an Endoloop

Colonic inflammatory fibroid polyp (IFP) is an uncommon benign polypoid lesion, which is composed of fibroblasts, numerous small vessels and edematous connective tissue with marked eosinophilic inflammatory cell infiltration. This condition is frequently detected in the stomach and small intestine, but uncommon in the colon. Although IFP is a benign lesion, surgical resections are performed in most colonic cases because the polyps are usually too large to resect endoscopically. Only three patients underwent endoscopic polypectomy in our literature reviews. Here, we present a case of IFP in the descending colon successful endoscopically resected using a novel technique of trapping its stalk with an endoloop, forming the stalk into an omega shape, and then dissecting the stalk with a needle knife