For distribution - thks

[CM ICTP - Trieste]

SEMINAR on  Disorder and strong electron correlations



Thursday, 24 May   -    11:00 a.m.



Lecture Room 'C',  Main Bldg.- terrace level





J. VON DELFT   ( Ludwig-Maximilians Universität München )


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


Abstract

	Transmission phase measurements of many-electron quantum dots  (small 
mean level spacing \delta) revealed universal phase lapses by \pi 
between consecutive resonances.  In contrast, for dots with only a few 
electrons (large \delta) 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 correlations and arbitrary level-lead couplings 
reproduces the generic features of the observed behavior.  The 
universal behavior at small follows from Fano-type antiresonances of 
pairs of renormalized single-particle levels.