Quantum Switch and Efficient Spin-Filter in a System Consisting of Multiple Three-Quantum-Dot Rings

Using the non-equilibrium Keldysh Green's function technique, we investigate electron transport properties of a system consisting of multiple three-quantum-dot rings. The conductance as a function of the electron energy is numerically calculated. An antiresonance point emerges in the conductance spectra and evolves into a welldefned insulating band with the increasing number of three-quantum-dot rings. The position of the well-defned insulating band can be modulated by varying the tunneling coupling strength between adjacent three-quantumdot rings. When an external magnetic flux is introduced, several to 100% spin-polarized windows will occur due to the Zeeman splitting. These results strongly suggest that this device may realize multiple functions including quantum switch and efcient spin fltering.