Correlated electron tunneling through two separate quantum dot systems with strong capacitive interdot coupling

A system consisting of two independently contacted quantum dots with strong electrostatic interaction shows interdot Coulomb blockade when the dots are weakly tunnel coupled to their leads. It is studied experimentally how the blockade can be overcome by correlated tunneling when tunnel coupling to the leads increases. The experimental results are compared with numerical renormalization group calculations using predefined (measured) parameters. Our results indicate Kondo correlations due to the electrostatic interaction in this double quantum dot system.