Quantum Computing and Quantum Simulation with Group-II Atoms

Recent experimental progress in controlling neutral group-II atoms for optical clocks, and in the production of degenerate gases with group-II atoms has given rise to novel opportunities to address challenges in quantum computing and quantum simulation. In these systems, it is possible to encode qubits in nuclear spin states, which are decoupled from the electronic state in the $^1$S$_0$ ground state and the long-lived $^3$P$_0$ metastable state on the clock transition. This leads to quantum computing scenarios where qubits are stored in long lived nuclear spin states, while electronic states can be accessed independently, for cooling of the atoms, as well as manipulation and readout of the qubits. The high nuclear spin in some fermionic isotopes also offers opportunities for the encoding of multiple qubits on a single atom, as well as providing an opportunity for studying many-body physics in systems with a high spin symmetry. Here we review recent experimental and theoretical progress in these areas, and summarise the advantages and challenges for quantum computing and quantum simulation with group-II atoms.Comment: 11 pages, 7 figures, review for special issue of "Quantum Information Processing" on "Quantum Information with Neutral Particles

Paleotectonics of a complex Miocene half graben formed above a detachment fault: The Diligencia basin, Orocopia Mountains, southern California

The Diligencia basin in the Orocopia Mountains of southeastern California has been one of the primary areas used to test the hypothesis of more than 300 km of dextral slip along the combined San Andreas/San Gabriel fault system. The Orocopia Mountains have also been the focus of research on deposition, deformation, metamorphism, uplift and exposure of the Orocopia Schist, which resulted from fl at-slab subduction during the latest Cretaceous/Paleogene Laramide orogeny. The uppermost Oligocene/Lower Miocene Diligencia Formation consists of more than 1500 m of nonmarine strata, including basalt fl ows and intrusions dated at 24-21 Ma. The base of the Diligencia Formation sits nonconformably on Proterozoic augen gneiss and related units along the southern basin boundary, where low-gradient alluvial fans extended into playa-lacustrine environments to the northeast. The northern basal conglomerate of the Diligencia Formation, which was derived from granitic rocks in the Hayfield Mountains to the north, sits unconformably on the Eocene Maniobra Formation. The northern basal conglomerate is overlain by more than 300 m of mostly red sandstone, conglomerate, mudrock and tuff. The basal conglomerate thins and fines westward; paleocurrent measurements suggest deposition on alluvial fans derived from the northeast, an interpretation consistent with a NW-SE-trending normal fault (present orientation) as the controlling structure of the half graben formed during early Diligencia deposition. This fault is hereby named the Diligencia fault, and is interpreted as a SW-dipping normal fault, antithetic to the Orocopia Mountains detachment and related faults. Deposition of the upper Diligencia Formation was infl uenced by a NE-dipping normal fault, synthetic with, and closer to, the exposed detachment faults. The Diligencia Formation is nonconformable on Mesozoic granitoids in the northwest part of the basin. Palinspastic restoration of the Orocopia Mountain area includes the following phases, each of which corresponds with microplate-capture events along the southern California continental margin: (1) Reversal of 240 km of dextral slip on the San Andreas fault (including the Punchbowl and other fault strands) in order to align the San Francisquito-Fenner-Orocopia Mountains detachment-fault system at 6 Ma. (2) Reversal of N-S shortening and 90° of clockwise rotation of the Diligencia basin and Orocopia Mountains, and 40 km of dextral slip on the San Gabriel fault between 12 and 6 Ma. (3) Reversal of 40° of clockwise rotation of the San Gabriel block (including Soledad basin and Sierra Pelona) and 30 km of dextral slip on the Canton fault between 18 and 12 Ma. These palinspastic restorations result in a coherent set of SW-NE-trending normal faults, basins (including Diligenica basin) and antiformal structures consistent with NW-SE-directed crustal extension from 24 to 18 Ma, likely resulting from the unstable configuration of the Mendocino triple junction

Deactivation processes in isolated aromatic heterocycles and pyrenes

In der vorliegenden Arbeit wurde erfolgreich eine neue Gasphasen-Apparatur für Photoelektronen-Imaging-Experimente simuliert, aufgebaut und in Verbindung mit einem ps-Lasersystem in Betrieb genommen. Neben dem Aufbau der Apparatur stand die Aufklärung der Dynamik angeregter Zustände von aromatischen Heterocyclen und Pyrenen im Fokus dieser Arbeit. Die untersuchten Moleküle wurden durch Resonanzverstärkte Mehrphotonenionisation in einem Molekularstrahlexperiment sowohl zeit-, als auch frequenzaufgelöst untersucht.In the presented work a new gas phase apparatus for photoelectron imaging experiments was succesfully simulated, constructed and together with a ps laser system put into operation. Besides the building of the new apparatus, the focus of this work was set to elucidate the excited state dynamics of selected aromatic heterocycles and pyrenes. The examined molecules were investigated by frequency- and time-resolved resonance enhanced multi photon ionisation spectroscopy using a molecular beam experiment