Second-Order Self-Consistent-Field Density-Matrix Renormalization Group

We present a matrix-product state (MPS)-based quadratically convergent density-matrix renormalization group self-consistent-field (DMRG-SCF) approach. Following a proposal by Werner and Knowles (JCP 82, 5053, (1985)), our DMRG-SCF algorithm is based on a direct minimization of an energy expression which is correct to second-order with respect to changes in the molecular orbital basis. We exploit a simultaneous optimization of the MPS wave function and molecular orbitals in order to achieve quadratic convergence. In contrast to previously reported (augmented Hessian) Newton-Raphson and super-configuration-interaction algorithms for DMRG-SCF, energy convergence beyond a quadratic scaling is possible in our ansatz. Discarding the set of redundant active-active orbital rotations, the DMRG-SCF energy converges typically within two to four cycles of the self-consistent procedureComment: 40 pages, 5 figures, 3 table

Measuring entanglement entropy through the interference of quantum many-body twins

Entanglement is one of the most intriguing features of quantum mechanics. It describes non-local correlations between quantum objects, and is at the heart of quantum information sciences. Entanglement is rapidly gaining prominence in diverse fields ranging from condensed matter to quantum gravity. Despite this generality, measuring entanglement remains challenging. This is especially true in systems of interacting delocalized particles, for which a direct experimental measurement of spatial entanglement has been elusive. Here, we measure entanglement in such a system of itinerant particles using quantum interference of many-body twins. Leveraging our single-site resolved control of ultra-cold bosonic atoms in optical lattices, we prepare and interfere two identical copies of a many-body state. This enables us to directly measure quantum purity, Renyi entanglement entropy, and mutual information. These experiments pave the way for using entanglement to characterize quantum phases and dynamics of strongly-correlated many-body systems.Comment: 14 pages, 12 figures (6 in the main text, 6 in supplementary material

Next-generation Process Management with ADEPT2

Short time-to-market, easy adaptation to changes in business environment, and robustness of processes are key requirements in today’s business world. In the IT area of Business Process Management (BPM), solutions claim to satisfy these new demands, but are still not sufficient.\ud In this paper we present a short overview on how these challenges are tackled by the ADEPT and AristaFlow projects and demonstrate a prototypical implementation

New Approaches for ab initio Calculations of Molecules with Strong Electron Correlation

Reliable quantum chemical methods for the description of molecules with dense-lying frontier orbitals are needed in the context of many chemical compounds and reactions. Here, we review developments that led to our newcomputational toolbo x which implements the quantum chemical density matrix renormalization group in a second-generation algorithm. We present an overview of the different components of this toolbox.Comment: 19 pages, 1 tabl

Probing the Superfluid to Mott Insulator Transition at the Single Atom Level

Quantum gases in optical lattices offer an opportunity to experimentally realize and explore condensed matter models in a clean, tunable system. We investigate the Bose-Hubbard model on a microscopic level using single atom-single lattice site imaging; our technique enables space- and time-resolved characterization of the number statistics across the superfluid-Mott insulator quantum phase transition. Site-resolved probing of fluctuations provides us with a sensitive local thermometer, allows us to identify microscopic heterostructures of low entropy Mott domains, and enables us to measure local quantum dynamics, revealing surprisingly fast transition timescales. Our results may serve as a benchmark for theoretical studies of quantum dynamics, and may guide the engineering of low entropy phases in a lattice

Efficacy of albendazole against the whipworm Trichuris trichiura - a randomised, controlled trial

Objectives and design. To test the efficacy of albendazole against the whipworm Trichuris trichiura for  school-based deworming in the south-western Cape, South Africa. Children infected with Trichuris were  randomised to 3 doses of albendazole (400; 800 or 1 200 mg), each repeated 4 times. The boy I girl ratio was 1. A group not infected With worms was treated with placebo, creating a negative control. Subjects and setting. Pupils at a primary school serving a wineproducing area approximately 90 km east of Cape Town.Outcome measures. Trichuris cure rates and reduction in the number of eggs/gin faeces, as well as the  infection dynamics of Trichuris and Ascaris during treatment with placebo.Results. Albendazole treatment was associated with Trichuris cure rates of 23% (400 mg), 56% (800  mg) and 67% (1 200 mg) after the final treatment. The corresponding reductions in the number of eggs/g of faeces were 96.8%, 99.3% and 99.7%. Environmental pollution by human faeces was confirmed because worm egg-negative children in the placebo group became egg-positive while the study was in progress.Conclusion. The 400 mg stat dose had a low Trichuris cure rate. To repeat the dose on 2 or 3 days would  increase cost, reduce compliance and complicate management. Albendazole cannot be used in deworming programmes in South Africa because it is a Schedule 4 prescription medicine. De-scheduling is needed urgently, particularly because of high efficacy against hookworm in KwaZulu-Natal and  neighbouring countries