Heedae Kim报告：Optical Aharonov-Bohm oscillations in a single quantum ring
Currently, quantum ring (QR) structures are of great interest for the optical Aharonov-Bohm (AB) effect. While the rotating charge in the shell of a type-II quantum dot (QD) determines the AB oscillation period, the orbital radius difference of the electrons and holes is the crucial parameter in a QR. Nevertheless, the individual behavior of each of the particles is not clear in a QR; either the radius is larger or one of them is localized as in the case of a type- II QD.
Recent measurements have shown that the morphology of a QR is anisotropic, where the rim height is not constant around the azimuthal angle based on atomic force microscope (AFM) images of a QR. We observed the presence of strongly localized states arises from the volcano-like QR structure, which corresponds to an excited state of the vertical confinement. The asymmetry was investigated in terms of the polarization dependence of excitons and biexcitons, where a large energy difference in the exciton emission energy for perpendicular polarizations was observed and the oscillator strengths were also compared using the photoluminescence decay rate. For perpendicular polarizations, the biexciton exhibits twice the energy difference seen for the exciton, a fact that may be attributed to a possible change in the selection rules for the lowered symmetry. Additionally, I have observed novel oscillations of a strongly correlated exciton pair, like a Wigner molecule, in a single QR, where the emission energy changes abruptly at the transition magnetic field with a fractional oscillation period compared to that of the exciton.
Heedae Kim博士，2008年本科毕业于德州大学奥斯汀分校，2013年博士毕业于牛津大学。毕业后先后在德国莱布尼兹研究所、亚利桑那州立大学从事博士后研究，现任日本北海道大学高级研究科学家、牛津大学研究员。主要从事量子光学器件的研究工作，在Nano Lett.等期刊发表学术论文多篇。