Autonomous Calibration of Single Spin Qubit Operations

Fully autonomous precise control of qubits is crucial for quantum information processing, quantum communication, and quantum sensing applications. It requires minimal human intervention on the ability to model, to predict and to anticipate the quantum dynamics [1,2], as well as to precisely control and calibrate single qubit operations. Here, we demonstrate single qubit autonomous calibrations via closed-loop optimisations of electron spin quantum operations in diamond. The operations are examined by quantum state and process tomographic measurements at room temperature, and their performances against systematic errors are iteratively rectified by an optimal pulse engineering algorithm. We achieve an autonomous calibrated fidelity up to 1.00 on a time scale of minutes for a spin population inversion and up to 0.98 on a time scale of hours for a Hadamard gate within the experimental error of 2%. These results manifest a full potential for versatile quantum nanotechnologies.Comment: 9 pages, 5 figure

Quantum Speed Limit and Optimal Control of Many-Boson Dynamics

We extend the concept of quantum speed limit -- the minimal time needed to perform a driven evolution -- to complex interacting many-body systems. We investigate a prototypical many-body system, a bosonic Josephson junction, at increasing levels of complexity: (a) within the two-mode approximation {corresponding to} a nonlinear two-level system, (b) at the mean-field level by solving the nonlinear Gross-Pitaevskii equation in a double well potential, and (c) at an exact many-body level by solving the time-dependent many-body Schr\"odinger equation. We propose a control protocol to transfer atoms from the ground state of a well to the ground state of the neighbouring well. Furthermore, we show that the detrimental effects of the inter-particle repulsion can be eliminated by means of a compensating control pulse, yielding, quite surprisingly, an enhancement of the transfer speed because of the particle interaction -- in contrast to the self-trapping scenario. Finally, we perform numerical optimisations of both the nonlinear and the (exact) many-body quantum dynamics in order to further enhance the transfer efficiency close to the quantum speed limit.Comment: 5 pages, 3 figures, and supplemental material (4 pages 1 figure

Precise ultra fast single qubit control using optimal control pulses

Ultra fast and accurate quantum operations are required in many modern scientific areas - for instance quantum information, quantum metrology and magnetometry. However the accuracy is limited if the Rabi frequency is comparable with the transition frequency due to the breakdown of the rotating wave approximation (RWA). Here we report the experimental implementation of a method based on optimal control theory, which does not suffer these restrictions. We realised the most commonly used quantum gates - the Hadamard (\pi/2 pulse) and NOT (\pi pulse) gates with fidelities ($F^{\mathrm{exp}}_{\pi/2}=0.9472\pm0.01$ and $F^{\mathrm{exp}}_{\pi}=0.993\pm0.016$), in an excellent agreement with the theoretical predictions ($F^{\mathrm{theory}}_{\pi/2}=0.9545$ and $F^{\mathrm{theory}}_{\pi}=0.9986$). Moreover, we demonstrate magnetic resonance experiments both in the rotating and lab frames and we can deliberately "switch" between these two frames. Since our technique is general, it could find a wide application in magnetic resonance, quantum computing, quantum optics and broadband magnetometry.Comment: New, updated version of the manuscript with supplementary informatio

Дослідження впливу фосфатів на біопродуктивність Chlorella vulgaris

Підвищений вміст фосфору у водоймах є основною причиною їхньої евтрофікації. Евтрофікація – процес зростання водної рослинності, який відбувається внаслідок перевищення балансу поживних речовин. Він супроводжується надмірним розвитком водоростей, особливо зелених, синьо-зелених і діатомових, переважанням небажаних видів планктону, порушенням життєдіяльності риб. Продукти метаболізму водоростей дають воді неприємний запах, можуть викликати шкірні алергічні реакції і шлунково-кишкові захворювання у людей і тварин. Після відмирання водорості виділяють у воду поліпептиди, аміак і проміжні продукти білкового розпаду. Це може призводити до підвищення вмісту фенолів, які мають канцерогенні властивості

Diagnosis of obstructive coronary artery disease using computed tomography angiography in patients with stable chest pain depending on clinical probability and in clinically important subgroups: meta-analysis of individual patient data

OBJECTIVE: To determine whether coronary computed tomography angiography (CTA) should be performed in patients with any clinical probability of coronary artery disease (CAD), and whether the diagnostic performance differs between subgroups of patients. DESIGN: Prospectively designed meta-analysis of individual patient data from prospective diagnostic accuracy studies. DATA SOURCES: Medline, Embase, and Web of Science for published studies. Unpublished studies were identified via direct contact with participating investigators. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Prospective diagnostic accuracy studies that compared coronary CTA with coronary angiography as the reference standard, using at least a 50% diameter reduction as a cutoff value for obstructive CAD. All patients needed to have a clinical indication for coronary angiography due to suspected CAD, and both tests had to be performed in all patients. Results had to be provided using 2×2 or 3×2 cross tabulations for the comparison of CTA with coronary angiography. Primary outcomes were the positive and negative predictive values of CTA as a function of clinical pretest probability of obstructive CAD, analysed by a generalised linear mixed model; calculations were performed including and excluding non-diagnostic CTA results. The no-treat/treat threshold model was used to determine the range of appropriate pretest probabilities for CTA. The threshold model was based on obtained post-test probabilities of less than 15% in case of negative CTA and above 50% in case of positive CTA. Sex, angina pectoris type, age, and number of computed tomography detector rows were used as clinical variables to analyse the diagnostic performance in relevant subgroups. RESULTS: Individual patient data from 5332 patients from 65 prospective diagnostic accuracy studies were retrieved. For a pretest probability range of 7-67%, the treat threshold of more than 50% and the no-treat threshold of less than 15% post-test probability were obtained using CTA. At a pretest probability of 7%, the positive predictive value of CTA was 50.9% (95% confidence interval 43.3% to 57.7%) and the negative predictive value of CTA was 97.8% (96.4% to 98.7%); corresponding values at a pretest probability of 67% were 82.7% (78.3% to 86.2%) and 85.0% (80.2% to 88.9%), respectively. The overall sensitivity of CTA was 95.2% (92.6% to 96.9%) and the specificity was 79.2% (74.9% to 82.9%). CTA using more than 64 detector rows was associated with a higher empirical sensitivity than CTA using up to 64 rows (93.4% v 86.5%, P=0.002) and specificity (84.4% v 72.6%, P<0.001). The area under the receiver-operating-characteristic curve for CTA was 0.897 (0.889 to 0.906), and the diagnostic performance of CTA was slightly lower in women than in with men (area under the curve 0.874 (0.858 to 0.890) v 0.907 (0.897 to 0.916), P<0.001). The diagnostic performance of CTA was slightly lower in patients older than 75 (0.864 (0.834 to 0.894), P=0.018 v all other age groups) and was not significantly influenced by angina pectoris type (typical angina 0.895 (0.873 to 0.917), atypical angina 0.898 (0.884 to 0.913), non-anginal chest pain 0.884 (0.870 to 0.899), other chest discomfort 0.915 (0.897 to 0.934)). CONCLUSIONS: In a no-treat/treat threshold model, the diagnosis of obstructive CAD using coronary CTA in patients with stable chest pain was most accurate when the clinical pretest probability was between 7% and 67%. Performance of CTA was not influenced by the angina pectoris type and was slightly higher in men and lower in older patients. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42012002780

Urbanizing refuge: interrogating spaces of displacement

Refugee spaces are emerging as quintessential geographies of the modern, yet their intimate and everyday spatialities remain under-explored. Rendered largely through geopolitical discourses, they are seen as biopolitical spaces where the sovereign can reduce the subject to bare life. In conceptualizing refugee spaces some scholars have argued that, although many camps grow and develop over time, they evolve their own unique form of urbanism that is still un-urban. This article challenges this idea of the camp as space of pure biopolitics and explores the politics of space in the refugee camp using urban debates. Using case studies from the Middle East and South Asia, it looks at how the refugee spaces developed and became informalized, and how people recovered their agency through ‘producing spaces’ both physically and politically. In doing so, it draws connections between refugee camps and other spaces of urban marginality, and suggests that refugee spaces can be seen as important sites for articulating new politics

Representations of British Chinese identities and British television drama: mapping the field

While important scholarship exists on the television representations of Asian American identities, research in the UK has been focused on African Caribbean and South Asian identities. Very little scholarly attention has been paid to televisual representations of British Chinese identities, despite the British Chinese constituting one of the larger and fastest growing ethnic minority groups within contemporary Britain. Informed by an understanding of the complexity of the term ‘British Chinese’, this article explores the representation of British Chinese identities in British television drama. Despite the long-standing absence and invisibility of such identities in British television, as perceived within the popular imagination in Britain and British Chinese discourses, the article finds that a larger number of British Chinese actors have found notable employment in British television than is commonly acknowledged or remembered within the popular imagination. The article draws on a database that deploys a range of research, including archive research at the BFI Reuben Library, to map the presence of British Chinese actors in British television drama since 1945. Through this historiographic focus, the article identifies some of the most significant trends in representations of British Chinese identities in British television drama. It then illustrates and provides more specific texture to these broader patterns through the close textual analysis of a case study, the BBC1 flagship series Sherlock (2010-present). It concludes by reflecting on the contemporary period, which has seen an influx of British Chinese actors in British television drama as well as high-profile diversity campaigning within Britain

Assessing PCR-Positive Acanthamoeba Keratitis-A Retrospective Chart Review

Ophthalmologists' diagnostic and treatment competence in Acanthamoeba keratitis varies widely. This investigator-initiated, retrospective, single-center chart review examined the electronic patient files regarding PCR-positive Acanthamoeba keratitis. We included corneal and contact lens assessments. We further reviewed the patient's medical history, corneal scraping results regarding viral or fungal co-infections, and the duration from symptom onset to final diagnosis. We identified 59 eyes of 52 patients from February 2010 to February 2023, with 31 of 52 (59.6%) being female patients. The median (IQR, range) patient age was 33 (25.3 to 45.5 [13 to 90]) years, and the mean (SD, range) time to diagnosis after symptom onset was 18 (10.5 to 35 [3 to 70]) days. Overall, 7 of 52 (7.7%) patients displayed a bilateral Acanthamoeba infection, and 48 (92.3%) used contact lenses at symptom onset. Regarding other microbiological co-infections, we found virologic PCR testing in 45 of 52 (86.5%) patients, with 3 (6.7%) positive corneal scrapings. Fungal cultures were performed in 49 of 52 (94.2%) patients, with 5 (10.2%) positive corneal scrapings. The medical treatment success rate was 45/46 (97.8%). This study raises awareness of patient education in contact lens handling and screens for further microbial co-infections in suspected Acanthamoeba cases

Two decades of seagrass monitoring data show drivers include ENSO, climate warming and local stressors

The drivers contributing to the trajectories of seagrass ecosystems is a key knowledge gap which limits our effectiveness in preventing their decline. Here, we present the key findings from the regional assessment of seagrass condition (shoot density) over time, which was undertaken to inform environmental impact assessment and monitoring as well as mitigation for the Westport program. To assess regional trends and drivers of these trends, data was collated from five regional seagrass monitoring programs, including the Cockburn Sound State Environmental Policy Seagrass Monitoring Program and marine park monitoring programs conducted by the Department of Biodiversity, Conservation and Attractions. These monitoring programs are located in the temperate waters of Western Australia (WA) along a latitudinal gradient (30-33°S, covering ~365 kms) and focus on the dominant habitat forming species, Posidonia sinuosa. WA has been designated as a hotspot for climate pressures, influenced by ocean warming and extreme climatic events and there are localised anthropogenic pressures that seagrasses are susceptible to. Hence, this regional approach enables an assessment of the relative importance of global (e.g. warming) and local (e.g. coastal development) pressures for seagrasses. The five regions assessed included the highly industrialised marine embayment of Cockburn Sound and four non-industrialised marine parks: Jurien Bay, Marmion, Shoalwater Islands and Geographe Bay within Ngari Capes (hereafter, Ngari Capes). Environmental predictors were selected based on an understanding of the major factors that affect seagrass condition, which included: depth, turbidity, sea surface temperature anomaly, mean sea surface summer temperature and habitat type. Hierarchical Generalised Additive Models (HGAMs) were run to examine the spatiotemporal trends in seagrass condition and to identify significant drivers as identified above, with the addition of region, site and geographic position. The key findings were: Across regions Posidonia sinuosa condition varied over time with a downward trend until 2017, after which there was a reversal in abundance. The variations aligned partly with El Niño Southern Oscillation. Spatial and temporal shifts in Posidonia sinuosa shoot density were reasonably explained by region, year, water depth, turbidity, mean sea surface temperature in summer (mean_summer) and maximum sea surface temperature anomaly (max_over). In some cases, there were differences in the effects of predictor variables on seagrass condition within each region (i.e. localised marginal effects). For example, mean_summer led to seagrass declines in Cockburn Sound but had very little effect in Jurien Bay. Seagrass condition differed among regions, with shoot densities in Ngari Capes significantly higher than Cockburn Sound. Increased mean_summer temperatures were a strong driver of the observed declines in Posidonia sinuosa condition, especially in Cockburn Sound and Marmion. Cooler sea surface temperature regime associated with higher latitude (Ngari Capes) appears to be ‘buffering’ Posidonia sinuosa condition from climate change effects. Oscillations in Posidonia sinuosa abundance were most strongly linked to the El Niño Southern Oscillation cycle in Jurien Bay and to a lesser extent, Cockburn Sound. Our results suggest that condition of Posidonia sinuosa across WA has declined in response to ocean warming and this was most pronounced in mid-latitude regions (31-32°S). Overall, it appears that in response to future climate change there will be variation in Posidonia sinuosa condition within regions and safeguarding healthy meadows as potential climate refuge sites is important to consider. Dredging and other coastal development activities that increase turbidity levels are likely to worsen Posidonia sinuosa condition given that low light impact seagrasses, and Cockburn Sound is quite susceptible to this. The variation in relationships between predictors and seagrass condition within regions highlights the importance of tailoring management actions to specific stressors and locations. Importantly, this work emphasises the value of long-term seagrass monitoring programs to evaluate ecosystem status in an era of rapid global change

Sediment burial negatively impacts the growth of seagrass Posidonia sinuosa

Burial disturbances affect foundation plant species in marine ecosystems. Deposition of dredge spoil can bury seagrass meadows yet we have limited threshold information to predict the trajectory of impact from burial or possible recovery. To investigate the response to burial by dredge spoil, established seagrass ramets of Posidonia sinuosa were collected from a population in Western Australia and exposed to cutter suction dredge spoil sediment. Plant responses were measured during a burial phase after 2, 4 and 8 weeks to assess the influence of duration to burial depths (0, 1, 4, 8 and 16 cm). Sediments were then removed, and recovery was monitored after 5 and 8 weeks. P. sinuosa was unaffected by burial of 1 and 4 cm whereas greater depths of burial led to negative impacts on ramet photophysiology and growth. In the 8 and 16 cm treatments, declines in seagrass growth were significant and sediment redox damaged seagrass health, reflecting conditions consistent with impaired plant physiology and anoxic sediment in the root zone. After burial was removed, seagrass growth rates in 8 and 16 cm treatments showed no recovery after 8 weeks. Although shoots were not lost, reduced growth and no shoot recovery in the short-term, 8 cm or more of dredge-deposition sediment could be used as a threshold for dredging management. Plant response under 16 cm of sediment suggests that the greater the seagrass burial depth the greater the adverse effect on the seagrass community including an impeded ability to recover and reduced population resilience