Transport through a quantum-dot-ring with one dot connected to two electron reservoirs

Making use of the equation of motion method and Keldysh Green function technique, we obtain a general current formula for a quantum-dot-ring with one of the dots connected to two electron reservoirs under a DC bias voltage. The transmission probability T ( ω ) as a function of electron ω curve is presented, which displays oscillation structure. The resonant states of the system are found to distribute within an interval centered at e 0 (the dot energy level) with a width of two times the tunnel coupling amplitude between two neighboring dots, the number of the resonant peaks agrees with N (the number of the dots) when inter-dot tunnel coupling is sufficiently large and an odd–even behavior appears at the Fermi energy.