Monday, 15 September, 2014
Transmission Phase in the Kondo Regime Revealed in a Two-Path Interferometer
S. Takada, C. Bäuerle, M. Yamamoto, K. Watanabe, S. Hermelin, T. Meunier, A. Alex, A. Weichselbaum, J. von Delft, A. Ludwig, A.D. Wieck, and S. Tarucha -
Phys. Rev. Lett., Vol. 113, 126601 (2014)
We report on the direct observation of the transmission phase shift through a Kondo correlated quantum dot by employing a new type of two-path interferometer. We observed a clear /2-phase shift, which persists up to the Kondo temperature TK. Above this temperature, the phase shifts by more than /2 at each Coulomb peak, approaching the behavior observed for the standard Coulomb blockade regime. These observations are in remarkable agreement with two-level numerical renormalization group calculations. The unique combination of experimental and theoretical results presented here fully elucidates the phase evolution in the Kondo regime.