Simulating photon counting from dynamic quantum emitters by exploiting zero-photon measurements

Many applications of quantum optics demand delicate quantum properties of light carefully tailored to accomplish a specific task. To this end, numerical simulations of quantum light sources are vital for designing, characterizing, and optimizing quantum photonic technology. Here, I show that exploiting information hidden in zero-photon measurement outcomes provides an exponential speedup for time-integrated photon counting simulations, realizing eight orders of magnitude reduction in the time to compute six-photon detection probabilities while achieving ten orders of magnitude higher precision compared to the state of the art. This enables simulations of large photonic experiments with an unprecedented level of physical detail. It can accelerate the design of sources to generate photonic resource states for quantum sensing and measurement-based quantum computing while capturing realistic imperfections. It also establishes a general theoretical framework to study dynamic interactions between stationary qubits mediated by measurements of flying qubits, which can be used to model distributed quantum computing and quantum communication.Comment: 9 pages, 3 figure

Quantum repeaters with individual rare-earth ions at telecommunication wavelengths

We present a quantum repeater scheme that is based on individual erbium and europium ions. Erbium ions are attractive because they emit photons at telecommunication wavelength, while europium ions offer exceptional spin coherence for long-term storage. Entanglement between distant erbium ions is created by photon detection. The photon emission rate of each erbium ion is enhanced by a microcavity with high Purcell factor, as has recently been demonstrated. Entanglement is then transferred to nearby europium ions for storage. Gate operations between nearby ions are performed using dynamically controlled electric-dipole coupling. These gate operations allow entanglement swapping to be employed in order to extend the distance over which entanglement is distributed. The deterministic character of the gate operations allows improved entanglement distribution rates in comparison to atomic ensemble-based protocols. We also propose an approach that utilizes multiplexing in order to enhance the entanglement distribution rate.Comment: 13 pages, 4 figure

Preparation of (Pb,Ba)TiO3 powders and highly oriented thin films by a sol-gel process

Solid solution Pb1-xBaxTiO3, with particular emphasis on Pb0.5Ba0.5TiO3, was prepared using a sol-gel process incorporating lead acetate trihydrate, barium acetate, and titanium isopropoxide as precursors, acetylacetone (2,4 pentanedione) as a chelating agent, and ethylene glycol as a solvent. The synthesis procedure was optimized by systematically varying acetylacetone: Ti and H2O:Ti molar ratios and calcination temperature. The resulting effects on sol and powder properties were studied using thermogravimetric analysis/differential scanning calorimetry, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller analysis, and x-ray diffraction (XRD). Crystallization of the perovskite structure occurred at a temperature as low as 450 °C. Thin films were prepared by spin coating on (100) MgO. Pyrolysis temperature and heating rate were varied, and the resultant film properties investigated using field-emission scanning electron microscopy, atomic force microscopy, and XRD. Under optimized conditions, highly oriented films were obtained at a crystallization temperature of 600 °C

Use of and Preference for Traditional Foods among the Belcher Island Inuit

To document the extent of use of traditional foods (marine and land mammals, birds, fish, and plants) and degree of preference for these foods in contemporary diets and culture, 102 households (98% of Inuit households) in the community of Sanikiluaq, Northwest Territories, Canada, were studied. During personal interviews, individuals estimated their frequency of use of traditional foods, systematically by season. In addition, 100 adults (from 96% of households) and 64 young people (84% of those in Grades 6-11) rated 41 foods (32 traditional and 9 market foods) for preference on a 5-point hedonic scale. According to respondents' estimates, traditional foods were used by all households, on average 1171±852 times annually. Fish and shellfish were most frequently consumed (523±490 times annually), followed by birds (254±204), sea mammals (184±161), berries (166±115), and land mammals (45±70). Preference ratings showed that most traditional foods were well-liked by both adults and young people, although adults rated 25 traditional foods higher (p<0.01) and 2 market foods lower (p<0.01) than young people did. Traditional foods remain an important part of contemporary Sanikiluaq lifestyle.Afin de documenter l'importance de l'utilisation des aliments traditionnels (mammifères marins et terrestres, oiseaux, poissons et plantes) et le degré de préférence pour ces aliments dans les régimes alimentaires et la culture actuels, on a fait une étude auprès de 102 foyers (98 p. cent de foyers inuit) dans la collectivité de Sanikiluaq (Territoires du Nord-Ouest [Canada]). Au cours d'interviews individuelles, les personnes estimaient la fréquence de leur utilisation des aliments traditionnels, de façon systématique, sur une base saisonnière. En outre, 100 adultes (provenant de 96 p. cent des foyers) et 64 jeunes (dont 84 p. cent scolarisés de la 6e à la 11e année) ont classé 41 aliments (32 traditionnels et 9 commerciaux) selon leur préférence sur une échelle hédonique de 5 points. Selon l'évaluation des répondants, les aliments traditionnels étaient consommés par tous les foyers, sur une base annuelle moyenne de 1171 ± 852 fois. C'est le poisson et les fruits de mer qui étaient consommés le plus souvent (523 ± 490 fois par an), suivis des oiseaux (254 ± 204), des mammifères marins (184 ± 161), des baies (166 ± 115), et des mammifères terrestres (45 ± 70). Le classement par préférence révèle que les adultes comme les jeunes apprécient la majorité des aliments traditionnels, bien que les adultes donnent à 25 aliments traditionnels une cote supérieure (p < 0,01) et à 2 aliments commerciaux une cote inférieure (p < 0,01) à celles données par les jeunes. Les aliments traditionnels continuent à jouer un rôle important dans le mode de vie contemporain de Sanikiluaq

Comparability of Microarray Data between Amplified and Non Amplified RNA in Colorectal Carcinoma

Microarray analysis reaches increasing popularity during the investigation of prognostic gene clusters in oncology. The standardisation of technical procedures will be essential to compare various datasets produced by different research groups. In several projects the amount of available tissue is limited. In such cases the preamplification of RNA might be necessary prior to microarray hybridisation. To evaluate the comparability of microarray results generated either by amplified or non amplified RNA we isolated RNA from colorectal cancer samples (stage UICC IV) following tumour tissue enrichment by macroscopic manual dissection (CMD). One part of the RNA was directly labelled and hybridised to GeneChips (HG-U133A, Affymetrix), the other part of the RNA was amplified according to the ?Eberwine? protocol and was then hybridised to the microarrays. During unsupervised hierarchical clustering the samples were divided in groups regarding the RNA pre-treatment and 5.726 differentially expressed genes were identified. Using independent microarray data of 31 amplified vs. 24 non amplified RNA samples from colon carcinomas (stage UICC III) in a set of 50 predictive genes we validated the amplification bias. In conclusion microarray data resulting from different pre-processing regarding RNA pre-amplification can not be compared within one analysis

Finding Cliques in Social Networks: A New Distribution-Free Model

We propose a new distribution-free model of social networks. Our definitions are motivated by one of the most universal signatures of social networks, triadic closure - the property that pairs of vertices with common neighbors tend to be adjacent. Our most basic definition is that of a c-closed graph, where for every pair of vertices u,v with at least c common neighbors, u and v are adjacent. We study the classic problem of enumerating all maximal cliques, an important task in social network analysis. We prove that this problem is fixed-parameter tractable with respect to c on c-closed graphs. Our results carry over to weakly c-closed graphs, which only require a vertex deletion ordering that avoids pairs of non-adjacent vertices with c common neighbors. Numerical experiments show that well-studied social networks tend to be weakly c-closed for modest values of c

Quantum repeaters based on individual electron spins and nuclear-spin-ensemble memories in quantum dots

Inspired by recent developments in the control and manipulation of quantum dot nuclear spins, which allow for the transfer of an electron spin state to the surrounding nuclear-spin ensemble for storage, we propose a quantum repeater scheme that combines individual quantum dot electron spins and nuclear-spin ensembles, which serve as spin-photon interfaces and quantum memories respectively. We consider the use of low-strain quantum dots embedded in high-cooperativity optical microcavities. Quantum dot nuclear-spin ensembles allow for the long-term storage of entangled states, and heralded entanglement swapping is performed using cavity-assisted gates. We highlight the advances in quantum dot technologies required to realize our quantum repeater scheme which promises the establishment of high-fidelity entanglement over long distances with a distribution rate exceeding that of the direct transmission of photons.Comment: 21 pages, 5 figure

Anticholinergic Drug Exposure and the Risk of Dementia: A Nested Case-Control Study

IMPORTANCE Anticholinergic medicines have short-term cognitive adverse effects, but itis uncertain whether long-term use of these drugs is associated with an increased risk of dementia.OBJECTIVE To assess associations between anticholinergic drug treatments and risk of dementia in persons 55 years or older.DESIGN, SETTING, AND PARTICIPANTS This nested case-control study took place in general practices in England that contributed to the QResearch primary care database. The study evaluated whether exposure to anticholinergic drugs was associated with dementia risk in 58 769 patients with a diagnosis of dementia and 225 574 controls 55 years or older matched by age, sex, general practice, and calendar time. Information on prescriptions for 56 drugs with strong anticholinergic properties was used to calculate measures of cumulative anticholinergic drug exposure. Data were analyzed from May 2016 to June 2018.EXPOSURES The primary exposure was the total standardized daily doses (TSDDs) of anticholinergic drugs prescribed in the 1 to 11 years prior to the date of diagnosis of dementia or equivalent date in matched controls (index date).MAIN OUTCOMES AND MEASURES Odds ratios (ORs) for dementia associated with cumulative exposure to anticholinergic drugs, adjusted for confounding variables.RESULTS Of the entire study population (284 343 case patients and matched controls), 179 365 (63.1%) were women, and the mean (SD) age of the entire population was 82.2 (6.8) years. The adjusted OR for dementia increased from 1.06 (95%CI, 1.03-1.09) in the lowest overall anticholinergic exposure category (total exposure of 1-90 TSDDs) to 1.49 (95%CI, 1.44-1.54) in the highest category (>1095 TSDDs), compared with no anticholinergic drug prescriptions in the 1 to 11 years before the index date. There were significant increases in dementia risk for the anticholinergic antidepressants (adjusted OR [AOR], 1.29; 95%CI, 1.24-1.34), antiparkinson drugs (AOR, 1.52; 95%CI, 1.16-2.00), antipsychotics (AOR, 1.70; 95% CI, 1.53-1.90), bladder antimuscarinic drugs (AOR, 1.65; 95%CI, 1.56-1.75), and antiepileptic drugs (AOR, 1.39; 95%CI, 1.22-1.57) all for more than 1095 TSDDs. Results were similar when exposures were restricted to exposure windows of 3 to 13 years (AOR, 1.46; 95%CI, 1.41-1.52) and 5 to 20 years (AOR, 1.44; 95%CI, 1.32-1.57) before the index date for more than 1095 TSDDs. Associations were stronger in cases diagnosed before the age of 80 years. The population-attributable fraction associated with total anticholinergic drug exposure during the 1 to 11 years before diagnosis was 10.3%.CONCLUSIONS AND RELEVANCE Exposure to several types of strong anticholinergic drugs is associated with an increased risk of dementia. These findings highlight the importance of reducing exposure to anticholinergic drugs in middle-aged and older people