A subradiant optical mirror formed by a single structured atomic layer

Efficient and versatile interfaces for the interaction of light with matter are an essential cornerstone for quantum science. A fundamentally new avenue of controlling light-matter interactions has been recently proposed based on the rich interplay of photon-mediated dipole-dipole interactions in structured subwavelength arrays of quantum emitters. Here we report on the direct observation of the cooperative subradiant response of a two-dimensional (2d) square array of atoms in an optical lattice. We observe a spectral narrowing of the collective atomic response well below the quantum-limited decay of individual atoms into free space. Through spatially resolved spectroscopic measurements, we show that the array acts as an efficient mirror formed by only a single monolayer of a few hundred atoms. By tuning the atom density in the array and by changing the ordering of the particles, we are able to control the cooperative response of the array and elucidate the interplay of spatial order and dipolar interactions for the collective properties of the ensemble. Bloch oscillations of the atoms out of the array enable us to dynamically control the reflectivity of the atomic mirror. Our work demonstrates efficient optical metamaterial engineering based on structured ensembles of atoms and paves the way towards the controlled many-body physics with light and novel light-matter interfaces at the single quantum level.Comment: 8 pages, 5 figures + 12 pages Supplementary Infomatio

Alltägliche Lebensführung: ein Ansatz bei Handlungsentscheidungen

Der Beitrag stellt die theoretische Grundlage eines Projekts zur Erforschung der Lebensführung zehnjähriger Kinder vor. Ausgangspunkt sind die Defizite einer Psychologie, die zwar ein Konzept der Persönlichkeit anbieten kann, aber keine Psychologie der praktisch handelnden Person, und deshalb nicht in der Lage ist, das Zustandekommen von Handlungsentscheidungen im Alltag zu erklären. Anhand empirischer Untersuchungen, bei denen zehnjährige Kinder an sieben Tagen ein lückenloses Protokoll über ihre Tätigkeiten abgegeben haben, sowie zusätzlicher Elterninterviews über die Alltagsgeschichte der Kinder seit ihrer Geburt wird das Spannungsfeld zwischen Intentionen und Beschränkungen, innerhalb dessen tagtäglich Entscheidungen getroffen werden müssen, aufgezeigt. Der Autor sucht nach generativen Prozessroutinen, die der Einzelne zur Führung seines alltäglichen Lebens herausbildet. Diese überdauernden Routinen entwickeln sich für ihn seit der frühen Kindheit und liegen den Entscheidungen zugrunde, die der Einzelne im Rahmen seiner alltäglichen Lebensführung trifft. (ICH

Profoundly reduced neovascularization capacity of bone marrow mononuclear cells derived from patients with chronic ischemic heart disease

Background— Cell therapy with bone marrow–derived stem/progenitor cells is a novel option for improving neovascularization and cardiac function in ischemic heart disease. Circulating endothelial progenitor cells in patients with coronary heart disease are impaired with respect to number and functional activity. However, whether this impairment also extends to bone marrow–derived mononuclear cells (BM-MNCs) in patients with chronic ischemic cardiomyopathy (ICMP) is unclea

Vitamin C inhibits endothelial cell apoptosis in congestive heart failure

Background - Proinflammatory cytokines like tumor necrosis factor- and oxidative stress induce apoptotic cell death in endothelial cells (ECs). Systemic inflammation and increased oxidative stress in congestive heart failure (CHF) coincide with enhanced EC apoptosis and the development of endothelial dysfunction. Therefore, we investigated the effects of antioxidative vitamin C therapy on EC apoptosis in CHF patients. Methods and Results - Vitamin C dose dependently suppressed the induction of EC apoptosis by tumor necrosis factor- and angiotensin II in vitro as assessed by DNA fragmentation, DAPI nuclear staining, and MTT viability assay. The antiapoptotic effect of vitamin C was associated with reduced cytochrome C release from mitochondria and the inhibition of caspase-9 activity. To assess EC protection by vitamin C in CHF patients, we prospectively randomized CHF patients in a double-blind trial to vitamin C treatment versus placebo. Vitamin C administration to CHF patients markedly reduced plasma levels of circulating apoptotic microparticles to 32±8% of baseline levels, whereas placebo had no effect (87±14%, P<0.005). In addition, vitamin C administration suppressed the proapoptotic activity on EC of the serum of CHF patients (P<0.001). Conclusions - Administration of vitamin C to CHF patients suppresses EC apoptosis in vivo, which might contribute to the established functional benefit of vitamin C supplementation on endothelial function

Quantum simulation of the universal features of the Polyakov loop

Lattice gauge theories are fundamental to our understanding of high-energy physics. Nevertheless, the search for suitable platforms for their quantum simulation has proven difficult. We show that the Abelian Higgs model in 1+1 dimensions is a prime candidate for an experimental quantum simulation of a lattice gauge theory. To this end, we use a discrete tensor reformulation to smoothly connect the space-time isotropic version used in most numerical lattice simulations to the continuous-time limit corresponding to the Hamiltonian formulation. The eigenstates of the Hamiltonian are neutral for periodic boundary conditions, but we probe the nonzero charge sectors by either introducing a Polyakov loop or an external electric field. In both cases we obtain universal functions relating the mass gap, the gauge coupling, and the spatial size which are invariant under the deformation of the temporal lattice spacing. We propose to use a physical multi-leg ladder of atoms trapped in optical lattices and interacting with Rydberg-dressed interactions to quantum simulate the model and check the universal features. Our results provide a path to the analog quantum simulation of lattice gauge theories with atoms in optical lattices.Comment: 9 pages, 6 figures, experimental content, supplementary material and coauthor (JZ) adde