量子点的少体问题、量子结构的输运现象及相关理论方法

Object of our research are focused on the recent progress in the study of quantum dots, quantum rings, quantum lines and carbon nanotubes; and to find new theoretical methods to explain new phenomena and results of experiments, and to predict new quantum effects.Background and contents of the project:◎.Few-body problems in quantum dots and rings. The dimension of quantum dots and rings is the lowest in low-dimensional nanostructures, in fact, they are strong-correlation systems with several particles. Lots of works made us know that to illustrate physical characters of quantum dots and rings, we must study the behavior of interacting particles in them. Hence we have emphasized the few-body problems with confined potential in quantum dots and rings, for example, quantum dots and rings with several electrons and neutral or charged excitons. We have investigated the effects of size and shape(include symmetry) of quantum dots and rings, impurities andexternal electric and magnetic fields, and have studied the interactions between these particles. Therefore we can illustrate the basic physical characters of a single quantum dot and ring such as optical and magnetic properties and so on. Based on all above, we also can study the properties of coupling quantum dots and rings.◎.Transport properties of quantum structures. In recent years, people can fabricate quite pure nanotubes and study the properties of transport. A lot of physical phenomena have been found, such as single-electron tunneling, Coulomb blocked, spin splitting of ground state and parity effects. Nanotube is a new-style one-dimensional material, and a fire-new object of our theoretical research. Our research emphasis is to study the influence of single and few point defects on the electrical local density of states, to reveal the dependence of quantum effects of conductance on relative position, intensity and symmetry of point defects, and to predict the modulation of conductance by transverse electric field. In addition, the spin tunneling of nanoscale magnets has been more deeply investigated.Main findings: we have obtained the effective potential model and the corresponding solution of GaInAs nanoring structures by nanoscale fabrication, which also can be used to study the nanorings with several electrons, excitons and impurities. we have explained the spectrum of experiments and predicted effects of magnetic oscillation of D-'s far-infrared spectrum and excitons' absorb spectrum. We have for the first time defined three kind of states and oscillation modes in double-barrier nanoring structures. we have illustrated the dependence of conductance of nanotubes on relative position, intensity and symmetry of point defects, and have predicted the periodic variation of local density of states related to the helicity, quantum interference and effect of magnetic impurities. We have also studied the modulating mechanism of transformation of nanotube between metal and semiconductor in a transverse electric field bydifferent doping, to provide theoretical foundation for the performance design of devices.

量子点、纳米棒、碳纳米管等量子系统是当前凝聚态物理学的研究热点。本项目针对国内外该领域研究的最新进展，寻求新的理论处理方法，以便解释新的有关实验现象，并预测可能的新效应。研究内容（1）量子点中的少体问题。（2）以GaN纳米棒、碳纳米管等新型一维牧衔韵螅芯科涫湓颂匦浴＃?）结合上述研究内容，建立和发展相应的理论方法。