Experimentally exploring compressed sensing quantum tomography

In the light of the progress in quantum technologies, the task of verifying the correct functioning of processes and obtaining accurate tomographic information about quantum states becomes increasingly important. Compressed sensing, a machinery derived from the theory of signal processing, has emerged as a feasible tool to perform robust and significantly more resource-economical quantum state tomography for intermediate-sized quantum systems. In this work, we provide a comprehensive analysis of compressed sensing tomography in the regime in which tomographically complete data is available with reliable statistics from experimental observations of a multi-mode photonic architecture. Due to the fact that the data is known with high statistical significance, we are in a position to systematically explore the quality of reconstruction depending on the number of employed measurement settings, randomly selected from the complete set of data, and on different model assumptions. We present and test a complete prescription to perform efficient compressed sensing and are able to reliably use notions of model selection and cross-validation to account for experimental imperfections and finite counting statistics. Thus, we establish compressed sensing as an effective tool for quantum state tomography, specifically suited for photonic systems.Comment: 12 pages, 5 figure

Incommensurate antiferromagnetic fluctuations in single-crystalline LiFeAs studied by inelastic neutron scattering

We present an inelastic neutron scattering study on single-crystalline LiFeAs devoted to the characterization of the incommensurate antiferromagnetic fluctuations at $\mathbf{Q}=(0.5\pm\delta, 0.5\mp\delta, q_l)$. Time-of-flight measurements show the presence of these magnetic fluctuations up to an energy transfer of 60 meV, while polarized neutrons in combination with longitudinal polarization analysis on a triple-axis spectrometer prove the pure magnetic origin of this signal. The normalization of the magnetic scattering to an absolute scale yields that magnetic fluctuations in LiFeAs are by a factor eight weaker than the resonance signal in nearly optimally Co-doped BaFe$_2$As$_2$, although a factor two is recovered due to the split peaks owing to the incommensurability. The longitudinal polarization analysis indicates weak spin space anisotropy with slightly stronger out-of-plane component between 6 and 12 meV. Furthermore, our data suggest a fine structure of the magnetic signal most likely arising from superposing nesting vectors.Comment: 9 pages, 8 figure

Overfeeding, Autonomic Regulation and Metabolic Consequences

The autonomic nervous system plays an important role in the regulation of body processes in health and disease. Overfeeding and obesity (a disproportional increase of the fat mass of the body) are often accompanied by alterations in both sympathetic and parasympathetic autonomic functions. The overfeeding-induced changes in autonomic outflow occur with typical symptoms such as adiposity and hyperinsulinemia. There might be a causal relationship between autonomic disturbances and the consequences of overfeeding and obesity. Therefore studies were designed to investigate autonomic functioning in experimentally and genetically hyperphagic rats. Special emphasis was given to the processes that are involved in the regulation of peripheral energy substrate homeostasis. The data revealed that overfeeding is accompanied by increased parasympathetic outflow. Typical indices of vagal activity (such as the cephalic insulin release during food ingestion) were increased in all our rat models for hyperphagia. Overfeeding was also accompanied by increased sympathetic tone, reflected by enhanced baseline plasma norepinephrine (NE) levels in both VMH-lesioned animals and rats rendered obese by hyperalimentation. Plasma levels of NE during exercise were, however, reduced in these two groups of animals. This diminished increase in the exercise-induced NE outflow could be normalized by prior food deprivation. It was concluded from these experiments that overfeeding is associated with increased parasympathetic and sympathetic tone. In models for hyperphagia that display a continuously elevated nutrient intake such as the VMH-lesioned and the overfed rat, this increased sympathetic tone was accompanied by a diminished NE response to exercise. This attenuated outflow of NE was directly related to the size of the fat reserves, indicating that the feedback mechanism from the periphery to the central nervous system is altered in the overfed state.

Real-World Effectiveness of Mepolizumab in Patients with Allergic and Non-Allergic Asthma

Jared Silver,1 Andrea Steffens,2 Benjamin Chastek,2 Arijita Deb3 1Medical Affairs, GSK, Durham, NC, USA; 2Optum, Eden Prairie, MN, USA; 3Value, Evidence and Outcomes, GSK, Upper Providence, PA, USACorrespondence: Arijita Deb, Value, Evidence and Outcomes, GSK, 1250 S Collegeville Road, Upper Providence, PA, 19426, USA, Tel +1 267 377-5717, Email [email protected]: Real-world data on mepolizumab in patients with severe asthma and allergic and non-allergic phenotypes are limited. This study investigated the effectiveness of mepolizumab treatment in patients with severe asthma with allergic and non-allergic phenotypes.Patients and Methods: This retrospective cohort study (GSK ID: 214148) used administrative claims data from the Optum Research Database. Eligible patients were ≥ 6 years of age with asthma and had ≥ 2 mepolizumab claims post-index. Index date was the first mepolizumab claim/administration (January 2016–December 2018). Patients were divided into two cohorts: allergic and non-allergic asthma, based on diagnosis codes, medication use and lab test results. Outcomes included the rate of asthma-related exacerbations and oral corticosteroid (OCS) use during the 12 months before (baseline period) and 12 months after (follow-up period) mepolizumab initiation. Study ended in December 2019.Results: Overall, 240 (44.6%) and 298 (55.4%) patients were included in the allergic and non-allergic asthma cohorts, respectively. Mean (standard deviation [SD]) counts of asthma-related exacerbations were significantly reduced from baseline to follow-up in both the allergic and non-allergic asthma cohorts (3.2 [2.5] to 2.1 [2.1], p < 0.001 and 2.5 [2.2] to 1.7 [1.9], p < 0.001, respectively). The mean number of OCS pharmacy claims was significantly decreased by 33.3% and 41.4% from baseline to follow-up in the allergic and non-allergic cohorts, respectively (p < 0.001); mean daily OCS dose significantly decreased by 30.6% and 45.4%, respectively (p < 0.001) as well as the mean number of OCS bursts, which decreased by 44.9% and 41.8%, respectively (p < 0.001). No significant differences were observed between cohorts in reductions in asthma exacerbations, counts of OCS pharmacy claims or OCS bursts (baseline to follow-up).Conclusion: Mepolizumab significantly reduced asthma exacerbations and OCS use in patients with allergic and non-allergic asthma, suggesting that mepolizumab provides real-world benefit in severe asthma irrespective of whether a patient has an allergic phenotype.Keywords: severe asthma, phenotype, exacerbation, oral corticosteroi

A Method to Polarize Stored Antiprotons to a High Degree

Polarized antiprotons can be produced in a storage ring by spin--dependent interaction in a purely electron--polarized hydrogen gas target. The polarizing process is based on spin transfer from the polarized electrons of the target atoms to the orbiting antiprotons. After spin filtering for about two beam lifetimes at energies $T\approx 40-170$ MeV using a dedicated large acceptance ring, the antiproton beam polarization would reach $P=0.2-0.4$. Polarized antiprotons would open new and unique research opportunities for spin--physics experiments in $\bar{p}p$ interactions

Quantum-dot lithium in zero magnetic field: Electronic properties, thermodynamics, and a liquid-solid transition in the ground state

Energy spectra, electron densities, pair correlation functions and heat capacity of a quantum-dot lithium in zero external magnetic field (a system of three interacting two-dimensional electrons in a parabolic confinement potential) are studied using the exact diagonalization approach. A particular attention is given to a Fermi-liquid -- Wigner-solid transition in the ground state of the dot, induced by the intra-dot Coulomb interaction.Comment: 12 pages, incl. 16 figure

Scheme Independence of g1p(x,Q2)g_1^p (x, Q^2)

We work with two general factorization schemes in order to explore the consequences of imposing scheme independence on $g_1^p (x, Q^2)$. We see that although the light quark sector is indifferent to the choice of a particular scheme, the extension of the calculations to the heavy quark sector indicates that a scheme like the $\bar{MS}$ is preferable.Comment: 11 pages, 2 figures. To appear in the Brief Reports of Phys. Rev.