Electron-Nuclear Spin Manipulation in Semiconductor Quantum Dots by Electrical Currents

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In this project we intend to control of the electron-nuclear spin dynamics in negatively charged quantum dots by a combination of optical and electrical driving pulses. One key ingredient is the usage of quasi-zero-dimensional systems (self-assembled CdSe/ZnSe quantum dots, localization centers in ZnO/ZnMgO quantum wells), where the number of nuclear spins seen by the resident electron is in the range of 100 or even below. The other key ingredient is the usage of micro-/nanoscale coils and wires on top of the semiconductor for applying magnetic field pulses with frequencies above one GHz and amplitudes of 10 mT and beyond on a micrometer length scale. In the preceeding funding period we have been able to demonstrate the technological and experimental feasibility and first proof-of-concept studies have been performed to manipulate the electron-nuclear spin system. Now, we intend to use combined magnetic and optical pulse sequences with tailored transverse and longitudinal field and defined temporal shape (MHz and GHz, -pulses, p/2 pulses etc.) (i) to investigate the fundamental mechanism of (coherent) electron and nuclear spin dynamics, (ii) to study electron and nuclear spin heating, (iii) to induce Rabi oscillations and (iv) finally to develop schemes for a coherent control of the electron-nuclear spin system. Elucidation of these new types of dynamical scenarios represents a starting point for the implementation of quantum logical functions based on the electron-nuclear spin system in quantum dots.