Dynamics and optical manipulation of nuclear spin in self assembled (InGa)As/GaAs quantum dots
| dc.contributor.advisor | Yakovlev, Dmitri R. | |
| dc.contributor.author | Flisinski, Karl | |
| dc.contributor.referee | Stolze, Joachim | |
| dc.date.accepted | 2014-03-07 | |
| dc.date.accessioned | 2014-04-01T07:16:04Z | |
| dc.date.available | 2014-04-01T07:16:04Z | |
| dc.date.issued | 2014-04-01 | |
| dc.description.abstract | Nuclei 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.identifier.uri | http://hdl.handle.net/2003/33005 | |
| dc.identifier.uri | http://dx.doi.org/10.17877/DE290R-13434 | |
| dc.language.iso | en | de |
| dc.subject | Hanle effect | en |
| dc.subject | Nuclear magnetic resonance (NMR) | en |
| dc.subject | Nuclear spin cooling | en |
| dc.subject | Negative circular polarisation (NCP) | en |
| dc.subject | Kramer's doublets | en |
| dc.subject | Self assembled quantum dots | en |
| dc.subject | Overhauser field | en |
| dc.subject | Nuclear spin fluctuation | en |
| dc.subject.ddc | 530 | |
| dc.title | Dynamics and optical manipulation of nuclear spin in self assembled (InGa)As/GaAs quantum dots | en |
| dc.type | Text | de |
| dc.type.publicationtype | doctoralThesis | de |
| dcterms.accessRights | open access |