We study the conductance of a quantum “T junction” coupled to two electron reservoirs and a quantum dot. In the absence of electron-electron interactions, the conductance $g$ is sensitive to interference between trajectories which enter the dot and those which bypass it. We show that including an intradot charging interaction has a marked influence: it can enforce a coherent response from the dot at temperatures much larger than the single-particle level spacing $\Delta$. The result is large oscillations of $g$ as a function of the voltage applied to a gate that is capacitively coupled to the dot. Without interactions, the conductance has only a weak interference signature when $T>\mathrm{}\Delta$.

• Received 15 May 2001

DOI:https://doi.org/10.1103/PhysRevLett.87.186801