Asymmetries of the conductance matrix in a three-terminal quantum ring in the Coulomb blockade regime

The conductance matrix of a three-terminal quantum ring has been measured in the Coulomb blockade regime for strong coupling to the leads. In contrast to multi-terminal quantum dots in the weak coupling regime, we find that the conductance matrix is asymmetric. This is a direct evidence of the relevance of phase coherence in transport experiments through quantum dots strongly coupled to the leads.