G. Hackenbroich et Ha. Weidenmuller, ABSENCE OF THERMAL SMEARING FOR THE TRANSMISSION PHASE THROUGH A QUANTUM-DOT, Europhysics letters, 38(2), 1997, pp. 129-134
We derive the phase theta of the Aharonov-Bohm oscillations of a multi
-terminal electron ring with a quantum dot in one of its arms. We show
i) that theta varies smoothly by pi at each transmission peak of the
system. We also find ii) that theta drops sharply by pi between the pe
aks if consecutive peaks have similar resonance parameters. The charac
teristic energy scale for ii) is of the order of the intrinsic resonan
ce width Gamma. This fact can be employed to measure Gamma in a novel
way.