Four-photon orbital angular momentum entanglement

Quantum entanglement shared between more than two particles is essential to foundational questions in quantum mechanics, and upcoming quantum information technologies. So far, up to 14 two-dimensional qubits have been entangled, and an open question remains if one can also demonstrate entanglement of higher-dimensional discrete properties of more than two particles. A promising route is the use of the photon orbital angular momentum (OAM), which enables implementation of novel quantum information protocols, and the study of fundamentally new quantum states. To date, only two of such multidimensional particles have been entangled albeit with ever increasing dimensionality. Here we use pulsed spontaneous parametric downconversion (SPDC) to produce photon quadruplets that are entangled in their OAM, or transverse-mode degrees of freedom; and witness genuine multipartite Dicke-type entanglement. Apart from addressing foundational questions, this could find applications in quantum metrology, imaging, and secret sharing.Comment: 5 pages, 4 figure

Ultrafast Optical Response of a High Reflectivity GaAs/AlAs Bragg Mirror

Quantum Matter and Optic

High finesse opto-mechanical cavity with a movable thirty-micron-size mirror

Quantum Matter and Optic

Angular redistribution of near-infrared emission from quantum dots in 3D photonic crystals

We study the angle-resolved spontaneous emission of near-infrared light sources in 3D photonic crystals over a wavelength range from 1200 to 1550 nm. To this end PbSe quantum dots are used as light sources inside titania inverse opal photonic crystals. Strong deviations from the Lambertian emission profile are observed. An attenuation of 60 % is observed in the angle dependent radiant flux emitted from the samples due to photonic stop bands. At angles that correspond to the edges of the stop band the emitted flux is increased by up to 34 %. This increase is explained by the redistribution of Bragg-diffracted light over the available escape angles. The results are quantitatively explained by an expanded escape-function model. This model is based on diffusion theory and adapted to photonic crystals using band structure calculations. Our results are the first angular redistributions and escape functions measured at near-infrared, including telecom, wavelengths. In addition, this is the first time for this model to be applied to describe emission from samples that are optically thick for the excitation light and relatively thin for the photoluminesence light.Comment: 24 pages, 8 figures (current format = single column, double spaced

Schistosoma mansoni infection alters the host pre-vaccination environment resulting in blunted Hepatitis B vaccination immune responses

Schistosomiasis is a disease caused by parasitic flatworms of the Schistosoma spp., and is increasingly recognized to alter the immune system, and the potential to respond to vaccines. The impact of endemic infections on protective immunity is critical to inform vaccination strategies globally. We assessed the influence of Schistosoma mansoni worm burden on multiple host vaccine-related immune parameters in a Ugandan fishing cohort (n = 75) given three doses of a Hepatitis B (HepB) vaccine at baseline and multiple timepoints post-vaccination. We observed distinct differences in immune responses in instances of higher worm burden, compared to low worm burden or non-infected. Concentrations of pre-vaccination serum schistosome-specific circulating anodic antigen (CAA), linked to worm burden, showed a significant bimodal distribution associated with HepB titers, which was lower in individuals with higher CAA values at month 7 post-vaccination (M7). Comparative chemokine/cytokine responses revealed significant upregulation of CCL19, CXCL9 and CCL17 known to be involved in T cell activation and recruitment, in higher CAA individuals, and CCL17 correlated negatively with HepB titers at month 12 post-vaccination. We show that HepB-specific CD4(+) T cell memory responses correlated positively with HepB titers at M7. We further established that those participants with high CAA had significantly lower frequencies of circulating T follicular helper (cTfh) subpopulations pre- and post-vaccination, but higher regulatory T cells (Tregs) post-vaccination, suggesting changes in the immune microenvironment in high CAA could favor Treg recruitment and activation. Additionally, we found that changes in the levels of innate-related cytokines/chemokines CXCL10, IL-1 & beta;, and CCL26, involved in driving T helper responses, were associated with increasing CAA concentration. This study provides further insight on pre-vaccination host responses to Schistosoma worm burden which will support our understanding of vaccine responses altered by pathogenic host immune mechanisms and memory function and explain abrogated vaccine responses in communities with endemic infections.Author summarySchistosomiasis drives host immune responses for optimal pathogen survival, potentially altering host responses to vaccine-related antigen. Chronic schistosomiasis and co-infection with hepatotropic viruses are common in countries where schistosomiasis is endemic. We explored the impact of Schistosoma mansoni (S. mansoni) worm burden on Hepatitis B (HepB) vaccination of individuals from a fishing community in Uganda. We demonstrate that higher schistosome-specific antigen (circulating anodic antigen, CAA) concentration pre-vaccination, is associated with lower HepB antibody titers post-vaccination at month 7. We show higher pre-vaccination levels of CCL17 in instances of high CAA that negatively associate with HepB antibody titers month 12 post-vaccination and coincided with lower frequencies of circulating T follicular helper cell populations (cTfh), proliferating antibody secreting cells (ASCs), and higher frequencies of regulatory T cells (Tregs). We also show that monocyte function is important in HepB vaccine responses, and high CAA is associated with alterations in the early innate cytokine/chemokine microenvironment. Our findings suggest that in individuals with high CAA and likely high worm burden, schistosomiasis can create an environment that is polarized against optimal host immune responses to the vaccine, which puts many endemic communities at risk for infection against HepB and other diseases that are preventable by vaccines.Cancer Signaling networks and Molecular Therapeutic

Bloch theory of entangled photon generation in non-linear photonic crystals

We present a quantum mechanical description of parametric down-conversion and phase-matching of Bloch-waves in non-linear photonic crystals. We discuss the theory in one-dimensional Bragg structures giving a recipe for calculating the down-converted emission strength and direction. We exemplify the discussion by making explicit analytical predictions for the emission amplitude and direction from a one-dimensional structure that consists of alternating layers of Al0.4Ga0.6As and Air. We show that the emission is suitable for the extraction of polarization-entangled photons

EXPERIMENTS TO TEST « PARAMAGNON THEORIES » : ELECTRICAL RESISTIVITY, LOW TEMPERATURE SPECIFIC HEAT AND MAGNETIZATION MEASUREMENTS ON Ni3Al AND Ni3Ga REVIEWED

On passe en revue les expériences qui appuient les théories du paramagnon. La résistivité électrique à basse température présente des effets de paramagnon prononcés tandis que les mesures de chaleur spécifique ne sont pas en accord avec la théorie. On s'attend à ce que les effets sur l'aimantation à basse température soient trop petits pour être observables dans les systèmes Ni3Al et Ni3Ga.A review of some experiments which can support paramagnon theories is given. The electrical resistivity at low temperatures shows pronounced paramagnon effects, whereas the specific heat measurements are not unambiguously supporting the theory. The effects in low temperature magnetization measurements are expected to be too small to be observable in the Ni3Al and Ni3Ga systems

Latent class analysis to evaluate performance of point-of-care CCA for low-intensity Schistosoma mansoni infections in Burundi

Background: Kato-Katz examination of stool smears is the field-standard method for detecting Schistosoma mansoni infection. However, Kato-Katz misses many active infections, especially of light intensity. Point-of-care circulating cathodic antigen (CCA) is an alternative field diagnostic that is more sensitive than Kato-Katz when intensity is low, but interpretation of CCA-trace results is unclear. To evaluate trace results, we tested urine and stool specimens from 398 pupils from eight schools in Burundi using four approaches: two in Burundi and two in a laboratory in Leiden, the Netherlands. In Burundi, we used Kato-Katz and point-of-care CCA (CCAB). In Leiden, we repeated the CCA (CCAL) and also used Up-Converting Phosphor Circulating Anodic Antigen (CAA). Methods: We applied Bayesian latent class analyses (LCA), first considering CCA traces as negative and then as positive. We used the LCA output to estimate validity of the prevalence estimates of each test in comparison to the population-level infection prevalence and estimated the proportion of trace results that were likely true positives. Results: Kato-Katz yielded the lowest prevalence (6.8%), and CCAB with trace considered positive yielded the highest (53.5%). There were many more trace results recorded by CCA in Burundi (32.4%) than in Leiden (2.3%). Estimated prevalence with CAA was 46.5%. LCA indicated that Kato-Katz had the lowest sensitivity: 15.9% [Bayesian Credible Interval (BCI): 9.2–23.5%] with CCA-trace considered negative and 15.0% with trace as positive (BCI: 9.6–21.4%), implying that Kato-Katz missed approximately 85% of infections. CCAB underestimated disease prevalence when trace was considered negative and overestimated disease prevalence when trace was considered positive, by approximately 12 percentage points each way, and CAA overestimated prevalence in both models. Our results suggest that approximately 52.2% (BCI: 37.8–5.8%) of the CCAB trace readings were true infections. Conclusions: Whether measured in the laboratory or the field, CCA outperformed Kato-Katz at the low infection intensities in Burundi. CCA with trace as negative likely missed many infections, whereas CCA with trace as positive overestimated prevalence. In the absence of a field-friendly gold standard diagnostic, the use of a variety of diagnostics with differing properties will become increasingly important as programs move towards elimination of schistosomiasis. It is clear that CCA is a valuable tool for the detection and mapping of S. mansoni infection in the field and CAA may be a valuable field tool in the future

Association of Schistosomiasis and HIV infection in Tanzania.

Animal and human studies suggest that Schistosoma mansoni infection may increase risk of human immunodeficiency virus (HIV) acquisition. Therefore, we tested 345 reproductive age women in rural Tanzanian villages near Lake Victoria, where S. mansoni is hyperendemic, for sexually transmitted infections (STIs) and schistosomiasis by circulating anodic antigen (CAA) serum assay. Over one-half (54%) had an active schistosome infection; 6% were HIV-seropositive. By univariate analysis, only schistosome infection predicted HIV infection (odds ratio [OR] = 3.9, 95% confidence interval = [1.3-12.0], P = 0.015) and remained significant using multivariate analysis to control for age, STIs, and distance from the lake (OR = 6.2 [1.7-22.9], P = 0.006). HIV prevalence was higher among women with more intense schistosome infections (P = 0.005), and the median schistosome intensity was higher in HIV-infected than -uninfected women (400 versus 15 pg CAA/mL, P = 0.01). This finding suggests that S. mansoni infection may be a modifiable HIV risk factor that places millions of people worldwide at increased risk of HIV acquisition