Transmission through a mesoscopic ring with a quantum dot

The transmission through a mesoscopic ring with a quantum dot embedded in o ne of its arms is studied with a one-dimensional scattering model. The quan tum dot is approached by a quantum well scatterer. With the use of a scatte ring matrix describing the junctions between the leads and the ring, it is analytically shown that the quantum interference and the resonant tunneling dominate the transmission. When the state of the dot is far from a resonan ce, the system acts as a quantum wire with two separated stubs at both ends , However, when a resonant tunneling through the dot occurs, an extra phase shift may be introduced to the wave through the dot and then the quantum i nterference effect may be flipped. The dependence of the total transmission coefficient on the properties of the quantum dot is also presented. (C) 19 99 Elsevier Science B.V. All rights reserved.