Detailseite
Projekt
Strong correlations in multi-component quantum gases
Antragsteller
Professor Dr. Klaus Sengstock
Fachliche Zuordnung
Optik, Quantenoptik und Physik der Atome, Moleküle und Plasmen
Förderung
Förderung von 2007 bis 2015
Projektkennung
Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 28567861
The investigation of intriguing physical effects provoked by strong correlations in ultracold quantum gases has matured into a very active field of research at the interlink between atomic and condensed matter physics. The Research Unit FOR801 precisely acts at this interface and contributes to the international development.The exceptional control available in systems of ultracold atoms allows for the realization of a whole wealth of model Hamiltonians often originally invoked in the context of solid state physics. The opportunity to prepare very clean, defect-free systems in hand with the tunability of particle interaction, lattice parameters and dimensionality opens up the possibility to accurately test predictions of underlying theoretical models which are at the heart of condensed matter physics, the Bose-Hubbard model being one of the most prominent examples.Within the first funding period of this Forschergruppe considerable progress in preparing and detecting thus far unexplored strongly correlated quantum gas systems has been obtained in the Hamburg group. The ability to enter the regime of strong correlations in triangular and hexagonal lattice geometries as well as the implementation of fully momentum-resolved Bragg spectroscopy to explore and identify novel phases and excitations are two of the fundamental achievements in this context.In the second funding period we intend to continuatively investigate strongly correlated Spinor systems as well as Fermi-Bose mixtures in different kinds of lattice geometries and dimensionalities. This work will greatly benefit from the experimental achievements obtained in the first period and the concise collaboration with the theory and experimental groups in the Research Unit FOR801. Mutually beneficial development of theoretical descriptions suiting our experimental preconditions and techniques constitute a promising basis to prepare, identify and explore more complex phases of the multi-flavour quantum gas systems under consideration.In particular we will focus on the physics of Spinor condensates confined in a hexagonal optical lattice. We have recently investigated for the very first time the interesting aspects of an mF-dependent thus “magnetic” hexagonal lattice structure. Spin-dependent localization together with coherent collisional spin dynamics might give rise to interesting new effects like state-dependent phase transitions, a blockade of tunnelling and spin entanglement and transport. The first results clearly motivate to further study these systems and to obtain an in-depth understanding of the underlying physics and opportunities concerning quantum simulations within the second funding period. Transport properties in triangular and hexagonal lattices which are expected to be conceptually different from hyper- cubic lattices will be investigated and as a long-term goal we plan to study the physics of higher orbital system in hexagonal lattices promising the existence of frustrated new phases.A second central point within this project will be the investigation of novel phases of Fermi-Bose mixtures in optical lattices as a direct continuation of the experimental and theoretical work performed by the Hamburg group in the first funding period. Interesting phenomena such as the formation of charge density waves or the existence of quasi-particles such as polarons are predicted to occur in these mixed systems and shall be realized and studied in detail in the framework of this project. Fully momentum-resolved Bragg spectroscopy incorporated in the first three years of this Research Unit will serve as a tool to unambiguously identify these correlated many-body states. Furthermore we plan to set up a new three beam lattice, similar to that used to study Spinor condensates, for the Fermi-Bose experiment to grant access to thus far unexplored physical phenomena in the context of strongly correlated systems, i.e. grapheme-like physics in a hexagonal optical lattice. These investigations will be in close analogy to topics vividly discussed in condensed matter physics where exotic superconducting states and the influence of orbital effects are of highest interest. As a long-term goals our profound experience in the field of Spinor BEC shall be extended to spin-changing dynamics and more generally spin-dependent phenomena of fermionic systems in optical lattices.
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