Phase evolution in a Kondo-correlated system

We measured the phase evolution of electrons as they traverse a quantum dot (QD) formed in a two-dimensional electron gas that serves as a Localized s pin. The traversal phase, determined by embedding the QD in a double path e lectron interferometer and measuring the quantum interference of the electr on wave functions manifested by conductance oscillation as a function of a weak magnetic field, evolved by pi radians, a range twice as Large as theor etically predicted. As the correlation weakened, a gradual transition to th e familiar phase evolution of a QD was observed, The specific phase evoluti on observed is highly sensitive to the onset of Kondo correlation, possibly serving as an alternative fingerprint of the Kondo effect.