Mesoscopic to universal crossover of transmission phase of multi-level quantum dots

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Transmission phase αmeasurements of many-electron quantum dots (small mean level spacing δ) revealed universal phase lapses by πbetween consecutive resonances. In contrast, for dots with only a few electrons (large δ), the appearance or not of a phase lapse depends on the dot parameters. We show that a model of a multi-level quantum dot with local Coulomb interactions and arbitrary level-lead couplings reproduces the generic features of the observed behavior. The universal behavior of αfor small δfollows from Fano-type antiresonances of the renormalized single-particle levels.