Driven quantum transport on the nanoscale

We explore the prospects to control by use of time-dependent fields quantum transport phenomena in nanoscale systems. In particular, we study for driven conductors the electron current and its noise properties. We review recent corresponding theoretical descriptions which are based on Floquet theory. Alternative approaches, as well as various limiting approximation schemes are investigated and compared. The general theory is subsequently applied to different representative nanoscale devices, like the non-adiabatic pumps, molecular gates, molecular quantum ratchets, and molecular transistors. Potential applications range from molecular wires under the influence of strong laser fields to microwave-irradiated quantum dots.Comment: 82 pages, 19 figures, elsart.cls, solved LaTeX/hyperref problem

Single-mode propagation of light in one-dimensional all-dielectric light-guiding systems

Numerical results are presented for single-mode guidance, which is based on photonic band gap (PBG) effect, in one-dimensional planar all-dielectric light-guiding systems. In such systems there may be two kinds of light-speed point (the intersection of a mode-dispersion curve and the light line of guiding region ambient medium): one is the intrinsic light-speed point that is independent of the guiding region width, and the other is the movable light-speed point that varies with the guiding region width. It is found that the intrinsic light-speed point plays an important role to form the single-mode regime by destroying the coexistence of the lowest guided TM and TE modes that are born with a degeneration point. A sufficient and necessary condition for intrinsic light-speed points is given. The transverse resonance condition is derived in the Maxwell optics frame, and it is shown that there is a significant revision to the traditional one in the ray optics model. A mode-lost phenomenon is exposed and this phenomenon suggests a way of how to identify PBG-guided fundamental modes. Quasi-cutoff-free index-guided modes in the PBG guiding structures, which appear when the higher-index layers are adjacent to the guiding region and the guiding region width is small, are exposed and analyzed as well.Comment: 13 pages, 8 figures, 32 reference