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__Ion crystals for quantum computing, simulation and non-equilibrium physics?__

Prof. Ferdinand Schmidt-Kaler, University of Mainz, Germany

Sunday, March 30th 2014, Danciger B seminar room, 12:00-14:30 o'clockI

on crystals are among the most controlled quantum systems. The crystal structure is controlled with high precision using the dynamic and the static Paul potentials. As an alternative to quantum computation which small linear crystals, shuttled in micro trap arrays, as pioneered by Wineland [Science 325, 1227 (2009), PRL109, 080501 (2012)] we aim for planar crystal structures, and investigate this structural transition [PRL 109, 263003 (2012)] also under non-equilibrium conditions [Nat. Comm. 4, 2290 (2013)]. Interactions for quantum magnetic simulations are mediated using laser interactions. State-dependent forces are generated with non-resonant Raman beams [NJP 14, 093042 (2012), PRL 107, 207209 (2011), PRL 108, 235701 (2012)]. A novel approach is the use of specific properties of Rydberg excitations for trapped ion crystals, we prepare a cold 40-Ca+ ion crystal, excite the S1/2 - D5/2 transition near 729nm and apply radiation near 123nm for Rydberg excitation. We report the investigation of mixed crystals of single and doubly ionized Ca, for mode design and structural configuration [arxiv 1306.1109] along the proposals [PRL 108, 023003 (2012), PRA 87, 052304 (2013)].

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__What has Bell's theorem to do with the absence of antimatter in our universe?__

Prof. Beatrix Heismayer, University of Vienna, Austria

John Stewart Bell was known and hired as a "particle physicist" when he came up with his work on hidden parameters exactly 50 years ago. The aim of this talk is to discuss whether his theorem can be brought back to those systems that do not build up ordinary matter and light, i.e. to the domain of Particle Physics. Indeed, massive K-meson pairs are copiously produced at accelerator facilities that are entangled in their strangeness quantum number, i.e. being in the particle or antiparticle state. Entanglement and its manifestations reveal differently than in quantum systems of low energy [1]. In particular, it turned out that there exists a connection between the violation of Bell's inequality and the tiny violation of the CP symmetry (C...charge conjugation, P...parity). The broken CP symmetry, verified in various accelerator facility experiments, shows a small difference between a world of matter and a world of antimatter. This relates two different powerful toolboxes in physics, entanglement and symmetries in Particle Physics. Moreover, the discovery of CP violation, also exactly 50 years old, can be attributed to the unsolved problem why we live in a universe dominated by matter, i.e. why has antimatter disappeared? In the last part of the talk I show that these meson-antimeson systems are a unique laboratory to study foundations of quantum mechanics, e.g., for testing different kinds of quantum eraser schemes or decoherence models or collapse models [2].

[1] Hiesmayr et al., "/Revealing Bell's Nonlocality for Unstable Systems in High Energy Physics/", EPJ C, Vol. 72, 1856 (2012).

[2] Brahami et al., "/Are collapse models testable with quantum oscillating systems? The case of neutrinos, mesons, chiral molecules/", Nature: Scientific Reports 3, 1952 (2013).

###
__Ion crystals for quantum computing, simulation and non-equilibrium physics?__

Prof. Ferdinand Schmidt-Kaler, University of Mainz, Germany

Sunday, March 30th 2014, Danciger B seminar room, 12:00-14:30 o'clock

Ion crystals are among the most controlled quantum systems. The crystal structure is controlled with high precision using the dynamic and the static Paul potentials. As an alternative to quantum computation which small linear crystals, shuttled in micro trap arrays, as pioneered by Wineland [Science 325, 1227 (2009), PRL109, 080501 (2012)] we aim for planar crystal structures, and investigate this structural transition [PRL 109, 263003 (2012)] also under non-equilibrium conditions [Nat. Comm. 4, 2290 (2013)]. Interactions for quantum magnetic simulations are mediated using laser interactions. State-dependent forces are generated with non-resonant Raman beams [NJP 14, 093042 (2012), PRL 107, 207209 (2011), PRL 108, 235701 (2012)]. A novel approach is the use of specific properties of Rydberg excitations for trapped ion crystals, we prepare a cold 40-Ca+ ion crystal, excite the S1/2 - D5/2 transition near 729nm and apply radiation near 123nm for Rydberg excitation. We report the investigation of mixed crystals of single and doubly ionized Ca, for mode design and structural configuration [arxiv 1306.1109] along the proposals [PRL 108, 023003 (2012), PRA 87, 052304 (2013)].

###
__What has Bell's theorem to do with the absence of antimatter in our universe?__

### Prof. Beatrix Heismayer, University of Vienna, Austria

John Stewart Bell was known and hired as a "particle physicist" when he came up with his work on hidden parameters exactly 50 years ago. The aim of this talk is to discuss whether his theorem can be brought back to those systems that do not build up ordinary matter and light, i.e. to the domain of Particle Physics. Indeed, massive K-meson pairs are copiously produced at accelerator facilities that are entangled in their strangeness quantum number, i.e. being in the particle or antiparticle state. Entanglement and its manifestations reveal differently than in quantum systems of low energy [1]. In particular, it turned out that there exists a connection between the violation of Bell's inequality and the tiny violation of the CP symmetry (C...charge conjugation, P...parity). The broken CP symmetry, verified in various accelerator facility experiments, shows a small difference between a world of matter and a world of antimatter. This relates two different powerful toolboxes in physics, entanglement and symmetries in Particle Physics. Moreover, the discovery of CP violation, also exactly 50 years old, can be attributed to the unsolved problem why we live in a universe dominated by matter, i.e. why has antimatter disappeared? In the last part of the talk I show that these meson-antimeson systems are a unique laboratory to study foundations of quantum mechanics, e.g., for testing different kinds of quantum eraser schemes or decoherence models or collapse models [2].

[1] Hiesmayr et al., "/Revealing Bell's Nonlocality for Unstable Systems in High Energy Physics/", EPJ C, Vol. 72, 1856 (2012).

[2] Brahami et al., "/Are collapse models testable with quantum oscillating systems? The case of neutrinos, mesons, chiral molecules/", Nature: Scientific Reports 3, 1952 (2013).