Current conserving AC quantum transport in two-dimensional mesoscopic systems

Chi Tang

Shi-Liang Zhu

Jian‐Xin Zhu, Z D Wang, Q. W. Shi

By extending Lieb and Liniger's (1963) Bose gas analysis to many hard-core bosons confined to a one-dimensional mesoscopic ring in the presence of Aharonov-Casher flux (AC), persistent fluxon currents are investigated for the first time, and are found to be periodic in the AC flux with period Phi 0=hc/e. The interesting mesoscopic parity effects due to evenness or oddness of the particle number N are discussed. More importantly, it is demonstrated exactly that, in the absence of the external AC flux, whether a self-sustained fluxon current exists depends only upon the choice of the boundary condition.

C. E. Creffield

We investigate the dynamics of two interacting electrons moving in a one‐dimensional array of quantum dots, under the influence of an ac field. The quantum dot array is modeled as a single‐band tight‐binding model of Hubbard‐type, and the system is analyzed by means of the Floquet approach. Our results show that the system exhibits two distinct regimes of behavior, depending on the ratio of the strength of the driving field to the inter‐electron Coulomb repulsion. When the ac‐field dominates an effect termed coherent destruction of tunneling occurs at certain frequencies, in which transport along the array is suppressed. In the other, weak‐driving, regime we find the surprising result that the two electrons can bind together into a single composite particle — despite the strong Coulomb repulsion between them — which can then be controlled by the ac field in an analogous way. We show how calculation of the system’s Floquet quasienergies explains these results, and thus how ac fields can be used to control the time evolution of entangled states in mesoscopic devices.

Senz, Volkmar

雄治 濱本