Decoupling and antiresonance in a quantum dot chain with two neighboring dots coupled to both leads

Electron transport through a quantum dot chain with two neighboring dots coupled to both leads is theoretically studied. In such a system, it is found that only for the even-numbered quantum dot structure with the same-number quantum dots coupled to each connecting dot, some eigenstates of the quantum dots decouple from the leads. Namely, all odd eigenstates decouple from the leads in the absence of magnetic flux, but all even eigenstates will decouple from the leads when a magnetic flux is introduced. In addition, by adjusting the magnetic fluxes through any subring, some eigenstates decouple from one lead but still couple to the other, and then some new antiresonances occur.