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dc.contributor.advisorYakovlev, Dmitri R.-
dc.contributor.authorFlisinski, Karl-
dc.description.abstractNuclei and electrons trapped in quantum dots create a strongly interacting spin system due to the strong localization of electrons in quantum dots. Due to strain in self-assembled (In,Ga,As)GaAs quantum dots quadrupole interactions appear which have a significant influence on the nuclear spin system. Therefore it is no longer possible to describe the nuclear spin system as one system with certain characteristics like a buildup time and decay time. Instead, in the case of strain the nuclear spin system can be separated into two subsystems, one with a nuclear spin state |±1/2⟩ which is weakly influenced by quadrupole interactions and the other with nuclear spin states |±3/2⟩, |±5/2⟩,… which is strongly influenced by quadrupole interactions. Each subsystem possesses different characteristic buildup and decay times of dynamic nuclear polarization generated by circular polarized light excitation of the quantum dots. A fast decay mechanism for polarized nuclei occurred during an interruption of the excitation beam for quantum dots with a single resident electron on a nanosecond scale. In relation to this phenomenon strong differences for the dynamic nuclear polarization are detected when either pulsed- or CW-lasers are used for excitation due to the short excitation time in relation to the repetition rate of the pulsed-laser. Further a new effect of optical pumping of nuclear spins in quantum dots is observed. The new effect, called resonant nuclear spin pumping, is observed in a magnetic field oriented perpendicularly to the excitation light beam (Voigt geometry). It creates a nuclear polarization perpendicular to the externally applied magnetic field.en
dc.subjectHanle effecten
dc.subjectNuclear magnetic resonance (NMR)en
dc.subjectNuclear spin coolingen
dc.subjectNegative circular polarisation (NCP)en
dc.subjectKramer's doubletsen
dc.subjectSelf assembled quantum dotsen
dc.subjectOverhauser fielden
dc.subjectNuclear spin fluctuationen
dc.titleDynamics and optical manipulation of nuclear spin in self assembled (InGa)As/GaAs quantum dotsen
dc.contributor.refereeStolze, Joachim-
dcterms.accessRightsopen access-
Appears in Collections:Experimentelle Physik II

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