Dynamically induced Kondo effect in double quantum dots

A new mechanism of resonance Kondo tunneling via a composite quantum dot (QD) is proposed. It is shown that, owing to the hidden dynamic spin symmetry, the Kondo effect can be induced by a finite voltage $eV$ applied to the contacts at an even number $N$ of electrons in a QD with zero spin in the ground state. As an example, a double QD is considered in a parallel geometry with $N=2$, which possesses the SO(4) type symmetry characteristic of a singlet-triplet pair. In this system, the Kondo peak of conductance appears at an $eV$ value compensating for the exchange splitting.