Transient and stationary transport properties of a three-subring quantum-dot structure

A systematical investigation into the transient and stationary transport properties of a circularly coupled triple quantum-dot system including three subrings has been carried out using the modified rate equations. It is shown that both the electron-occupation probabilities and the current flowing through the triple quantum-dot structure exhibit transient oscillations in the initial stage of the quantum dynamics and eventually evolve into stationary values. Furthermore, the influences on the stationary current caused by the magnetic field and the interdot Coulomb interaction are taken into account. It is demonstrated that with a variation of the magnetic flux the current shows the 2(1+n₁+n₂)π-period Aharonov-Bohm oscillation with 1:n₁:n₂ being the ratio of the magnetic fluxes penetrating three subrings φ, n₁φ, and n₂φ. Moreover, although the interdot Coulomb interactions have an obvious effect upon specific oscillation behaviors, they are not able to change the oscillation period. Lastly, together with the results of the one-ring and two-subring structures, we extend the three-subring result into an N-subring case. It is verified that the Aharonov-Bohm oscillation period of the stationary current is 2(1 + n ₁ +...+n_N?1)π when the ratio of the reduced magnetic flux threading into the N subrings is 1:n₁:...:n_N-1.