Quantum phase transition in coupled quantum dots

We study two quantum dots in the limit of strong dot-lead coupling and weak dot-dot tunneling. The model maps on Ising-coupled Kondo impurities. We argue that a new quantum critical fixed point exists at an intermediate value of the mutual capacitance, supporting non-Fermi-liquid behavior. We construct the total conductance across the double dot structure. It exhibits a strongly peaked behavior as a function of the mutual capacitance, gate voltage, and temperature.