SU(3) Kondo effect in spinless triple quantum dots

Abstract

We discuss a device-a purely capacitively coupled interacting triple quantum dot system in an external magnetic field-for the observation of the SU(3) Kondo effect, identified by the conductance being pinned to a characteristic value of 3/4 of the unitary limit. The Kondo effect occurs in two plateaus where the dot occupancy is pinned to an integer value, either 1 or 2. We discuss the thermodynamic and spectral properties of the corresponding triple-impurity model and establish how the presence of SU(3) Kondo screening can be identified in the temperature dependence of the conductance through one of the dots. We report results about the robustness of the SU(3) Kondo effect against various perturbations present in real experimental setups, namely unequal reservoir-dot tunneling couplings, gating effects, and nonvanishing interdot tunneling rates. Finally, we describe possible mechanisms to restore the SU(3) Kondo physics by properly tuning the on-site dot potentials. We briefly comment on the spinful case (i.e., the same system in the absence of the magnetic field), which has very different behavior and shows Kondo plateaus in conductance for all integer values of the occupancy, including at the particle-hole symmetric point.

Observation of the Kondo effect in a quadruple quantum dot

“…A variety of quantum phenomena are found, such as a transition between different quantum states 5,6 . On the basis of a relatively clear picture in the double dots system, some further study on the triple 11,12 and quadruple dots 13,19 in theory has been done. Several interesting physics, such as the Berezinskii-Kosterlitz-Thouless phase transition 26 or the existing of charge Kondo state, may be realized on these multiple dot systems.…”

Interaction-induced local moments in parallel quantum dots within the functional renormalization group approach

“…The numerical renormalization group (NRG) method provides a strightforward approach to describe spectral functions and conductivity of quantum dots in the presence of an interaction [15][16][17][18]. However, being very successful, this method requires significant computational effort, which grows exponentially with the number of interacting degrees of freedom.…”

Long-range exchange interaction in triple quantum dots in the Kondo regime

“…Recently considerable theoretical efforts have been made in the topic of serial TQDs, such as the equilibrium and nonequilibrium Kondo transport properties [16], Fermi-Liquid versus non-Fermi-liquid behavior [17], and two-channel Kondo physics [18]. In addition, the Kondo phenomenon in other structures of TQDs have been discussed as well, including the mirror symmetry TQDs [19][20][21], triangular TQDs [22][23][24][25], and parallel TQDs [26]. To the best of our knowledge, none of these works concern the long-range exchange interaction and its effect on the Kondo phenomenon in TQDs.…”