Multiple quantum NMR dynamics in a gas of spin-carrying molecules in fluctuating nanopores

The effect of Gaussian fluctuations of nanopores filled with a gas of spin-carrying molecules ($s=1/2$) on the multiple quantum (MQ) NMR dynamics is investigated at different variances and correlation times of the fluctuations. We show that the fluctuations smooth out the evolution of MQ NMR coherence intensities which rapidly oscillate as functions of time in the absence of fluctuations. The growth and decay of the MQ coherence clusters in the fluctuating nanopore are also investigated.Comment: 10 pages, 3 figure

Indirect decoherence in optical lattices and cold gases

The interaction of two--level atoms with a common heat bath leads to an effective interaction between the atoms, such that with time the internal degrees of the atoms become correlated or even entangled. If part of the atoms remain unobserved this creates additional indirect decoherence for the selected atoms, on top of the direct decoherence due to the interaction with the heat bath. I show that indirect decoherence can drastically increase and even dominate the decoherence for sufficiently large times. I investigate indirect decoherence through thermal black body radiation quantitatively for atoms trapped at regular positions in an optical lattice as well as for atoms at random positions in a cold gas, and show how indirect coherence can be controlled or even suppressed through experimentally accessible parameters.Comment: 12 pages, 1 figur

Der Umgang mit Forschungsdaten an der Leibniz Universität Hannover : Auswertung einer Umfrage und ergänzender Interviews 2015/16

Im Kontext des Projekts „Entwicklung eines institutionellen Konzepts zum Forschungsdatenmanagement an der Leibniz Universität Hannover“ wurden 2015/16 eine universitätsinterne Online-Umfrage und ergänzende Interviews durchgeführt. Deren Ergebnisse ermöglichen einen Einblick in den derzeitigen Umgang mit Forschungsdaten und eine Abschätzung des Bedarfs an Beratung, Schulung und technischer Infrastruktur seitens des wissenschaftlichen Personals. In diesem Bericht werden die Daten präsentiert und ausgewertet

Multiple quantum NMR of spin-carrying molecules in nanopores: high order corrections to the two-spin/two-quantum Hamiltonian

This paper is devoted to the multiple-quantum (MQ) NMR spectroscopy in nanopores filled by a gas of spin-carrying molecules (s=1/2) in a strong external magnetic field. It turned out that the high symmetry of the spin system in nanopores yields a possibility to overcome the problem of the exponential growth of the Hilbert space dimension with an increase in the number of spins and to investigate MQ NMR dynamics in systems consisting of several hundred spins. We investigate the dependence of the MQ coherence intensities on their order (the profile of the MQ coherence intensities) for a spin system governed by the standard MQ NMR Hamiltonian (the nonsecular two-quantum/two-spin Hamiltonian) together with the second order correction of the average Hamiltonian theory. It is shown that the profile depends on the value of this correction and varies from the exponential to the logarithmic one.Comment: 7 pages, 3 figure

Der Umgang mit Forschungsdaten an der Leibniz Universität Hannover. Auswertung einer Umfrage und ergänzender Interviews 2015/16

Im Kontext des Projekts „Entwicklung eines institutionellen Konzepts zum Forschungsdatenmanagement an der Leibniz Universität Hannover“ wurden 2015/16 eine universitätsinterne Online-Umfrage und ergänzende Interviews durchgeführt. Deren Ergebnisse ermöglichen einen Einblick in den derzeitigen Umgang mit Forschungsdaten und eine Abschätzung des Bedarfs an Beratung, Schulung und technischer Infrastruktur seitens des wissenschaftlichen Personals. In diesem Bericht werden die Daten präsentiert und ausgewertet

Quantitative Treatment of Decoherence

We outline different approaches to define and quantify decoherence. We argue that a measure based on a properly defined norm of deviation of the density matrix is appropriate for quantifying decoherence in quantum registers. For a semiconductor double quantum dot qubit, evaluation of this measure is reviewed. For a general class of decoherence processes, including those occurring in semiconductor qubits, we argue that this measure is additive: It scales linearly with the number of qubits.Comment: Revised version, 26 pages, in LaTeX, 3 EPS figure