Interaction-induced restoration of phase coherence - art. no. 186801

We study the conductance of a quantum "T junction" coupled to two electron reservoirs and a quantum dot. In the absence of electron-electron interacti ons, the conductance g is sensitive to interference between trajectories wh ich enter the dot and those which bypass it. We show that including an intr adot 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 o f the voltage applied to a gate that is capacitively coupled to the dot. Wi thout interactions, the conductance has only a weak interference signature when T > Delta.