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Kondo effect and singlet-triplet splitting in coupled quantum dots in a magnetic field

Vitaly N. Golovach·Daniel Loss
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Abstract

We study two tunnel-coupled quantum dots each with a spin 1/2 and attached to leads in the Coulomb blockade regime. We study the interplay between Kondo correlations and the singlet-triplet exchange splitting $K$ between the two spins. We calculate the cotunneling current with elastic and inelastic contributions and its renormalization due to Kondo correlations, away and at the degeneracy point K=0. We show that these Kondo correlations induce pronounced peaks in the conductance as function of magnetic field $B$, inter-dot coupling $t_0$, and temperature. Moreover, the long-range part of the Coulomb interaction becomes visibile due to Kondo correlations resulting in an additional peak in the conductance vs $t_0$ with a strong $B$-field dependence. These conductance peaks thus provide direct experimental access to $K$, and thus to a crucial control parameter for spin-based qubits and entanglement.

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Vitaly N. Golovach, Daniel Loss. 2001-09-09. Kondo effect and singlet-triplet splitting in coupled quantum dots in a magnetic field. https://doi.org/10.1209/epl%2Fi2003-00365-x

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