Low-dimensional Mesoscopic Physical Systems Of Current And Current Noise Spectrum

With the development of material technology and ultra-micro fabrication technique, the semiconductor microstructures with mesoscopic dimension have come within reach. As the typical representation for exhibiting quantum effects of low dimensional mesoscopic system, quantum dot (QD) has become one of the most active areas in mesoscopic physics in recent years. In this thesis, using the quantum master equation we present in some detail theoretical investigations on the quantum-transport properties of single-wall carbon nanotube quantum dot and quantum shuttle.The thesis consists of five chapters. At the beginning we introduce an infancy field—low dimensional mesoscopic quantum system. We centrally report on single-wall carbon nanotube and quantum shuttle as the two main realizations of this system. For self-consistence, Chapter 2 gives a brief introduction of Red-Field theory in an algebraic form. We use this theory to study single-wall carbon nanotube and single-dot quantum shuttle. Due to the nanometer size of these devices we treat quantum mechanically not only the electrical but also the mechanical degrees of freedom. Then we derive one of the main results of the thesis—number-resolved density matrix and generalized quantum master equation. This is a well-suited method to treat open quantum systems. In Chapter 3 based on this quantum master equation, we present another central result of this thesis—tunneling current and circuit current noise spectrum. In Chapter 4 We consider a special case where the concerned system is"frozen"at uncharged/charged equilibrium position and in lower excited states. At last we make a summary of this thesis.