Narrow Results

We develop a method for studying spatial distribution of the Knight shift using resistively-detected nuclear magnetic resonance (NMR) in an AlGaAs/GaAs quantum Hall device. By controlling the position of the dynamic nuclear polarization with the side-gate voltage, the spatial distribution of the NMR spectrum is investigated in a vicinity of quantum Hall edge channels. The value of Knight shift gradually changes in the region where the local Landau-level filling factor is between ν = 1 and ν = 2, implying that the change of the local electron spin polarization is detected in the edge channel.

The electron spin decoherence by nuclear spins in semiconductor quantum dots is caused by quantum entanglement between the electron and the nuclei. The many-body dynamics problem of the interacting nuclear spins can be solved with the pair-correlation approximation which treats the nuclear spin flip-flops as mutually independent. The nuclear spin dynamics can be controlled by simply flipping the electron spin so that the electron is disentangled from the nuclei and hence its lost coherence is restored.

Laser spectroscopy is a prominent tool in the study of nuclear ground and isomeric state properties. Being able to measure nuclear spins, magnetic dipole and electric quadrupole moments, and changes in mean-square charge radii, make it an effective probe of both single particle and collective phenomena. Topics of recent investigation have included: evolution of single particle levels and changing magicity in the vicinity of shell closures, emerging collectivity, establishing new isomeric states, and the first optical measurements of a transfermium element.