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Drittmittel

International Collaborative Research Centre TRR 160:
Coherent manipulation of interacting spin excitations in tailored semiconductors

[Link to TRR160 website]

  • A4 Coherent control of the electronic and nuclear spins in quantum dot ensembles
    with

    The project is focused on the quantitative theoretical description of coherent control and dynamic spin polarization in ensembles of quantum dots induced by ultrafast pumping by optical laser pulses. We describe the radiative decay of the intermediate trion states simultaneously considering the hyperfine coupling to baths of various nuclear spins due to the presence of different isotopes, the dipole-dipole interaction among the nuclear spins, and the nuclear quadrupolar interaction induced by strain fields. Quantum mechanical and semi-classical techniques combined with stochastic approaches will be employed to assess the effect of trains of pulses and to suggest protocols for spin manipulation. Novel foci are interactions between the spins of different quantum dots and spin inertia as measured by the laser pulses with modulated circular polarization. We will study both conventional quantum dots from III-V semiconductors as well as novel types of nanosystems such as organic/inorganic perovskites.

  • A7 Theory of spin-noise in semiconductor quantum dots
    with

    Spin-noise spectroscopy is an important technique for revealing the microscopic nature of spin decoherence in quantum dots. For its theoretical descriptions, isotropic and anisotropic variants of the central spin model will be investigated. Issues to be addressed are quantum mechanical effects in large spin baths, the computation of higher order correlators such as four-point correlators, and the description of nuclear spin noise and the correlations of the nuclear spins of different sub-ensembles. Furthermore, we want to address diluted baths, i.e., baths of small numbers of nuclear spins, and how they can be manipulated and how specific states of them can be prepared. We will also study correlations between the electron and nuclear spins and microscopic scenarios of nuclear polaron formation.

  • B8 fs-manipulation of charge-magnetism coupling in an antiferromagnetic semiconductor
    with

    The main goal of project B8 is to realize femtosecond spin-to-charge and charge-to-spin conversion in an AF semiconductor.The intrinsic physical complexity of our project demands both a thorough investigation of the ground state of our sample material and a tight collaboration between experiments and theory. Experimentally, we will implement a procedure allowing to disclose the real-time evolution of both the spin and charge systems. Theoretically, state-of-the-art modelling is needed to achieve a comprehensive understanding of the equilibrium and non-equilibrium relevant properties, since they are both generated by many body effects, electronic correlations and spin-charge coupling which are all notoriously arduous to handle.

 

DFG-Sachbeihilfe: UH 90/13-1

  • Nonequilibrium physics in quenched fermionic models in two dimensions
    In this project, we study nonequilibrium properties of strongly correlated systems which are subjected to various forms of driving: quenches, trains of pulses or continuous periodic driving. The considered models are correlated fermionic models or quantum spin systems.