Tetyana Kuzmenko

Magnetically tunable kondo-aharonov-bohm effect in a triangular quantum dot

The role of discrete orbital symmetry in mesoscopic physics is manifested in a system consisting of three identical quantum dots forming an equilateral triangle. Under a perpendicular magnetic field, this system demonstrates a unique combination of Kondo and Aharonov-Bohm features due to an interplay between continuous [spin-rotation SU(2)] and discrete (permutation C3v) symmetries, as well as U(1) gauge invariance. The conductance as a function of magnetic flux displays sharp enhancement or complete suppression depending on contact setups.

Dynamical symmetries in Kondo tunneling through complex quantum dots.

Kondo tunneling reveals hidden SO(n) dynamical symmetries of evenly occupied quantum dots. As is exemplified for an experimentally realizable triple quantum dot in parallel geometry, the possible values n=3,4,5,7 can be easily tuned by gate voltages. Following construction of the corresponding o(n) algebras, scaling equations are derived and Kondo temperatures are calculated. The symmetry group for a magnetic field induced anisotropic Kondo tunneling is SU(2) or SO(4).

Towards two-channel Kondo effect in triple quantum dot

The effective spin Hamiltonian of a triple quantum dot with odd electron occupation weakly connected in series with left (l) and right (r) metal leads is composed of two-channel exchange and co-tunneling terms. Renormalization group equations for the corresponding three exchange constants Jl, Jr and Jlr are solved (to third order). Since Jlr is relevant, the system is mapped on an anisotropic two-channel Kondo problem. The structure of the conductance as a function of temperature and gate voltage implies that in the weak- and intermediate-coupling regimes, two-channel Kondo physics persists at temperatures as low as several TK. At even electron occupation, the number of channels equals twice the spin of the triple dot (hence it is a fully screened impurity).

Dynamical and point symmetry of the Kondo effect in triangular quantum dot

In this work we concentrate on the point symmetry of a triangular triple quantum dot and its interplay with the spin rotation symmetry in the context of Kondo tunneling through this kind of artificial molecule. A fully symmetric triangular triple quantum dot is considered, consisting of three identical puddles with the same individual properties (energy levels and Coulomb blockade parameters) and inter-dot coupling (tunnel amplitudes and electrostatic interaction). The underlying Kondo physics is determined by the product of a discrete rotation symmetry group in real space and a continuous rotation symmetry in spin space. These symmetries are reflected in the resulting exchange hamiltonian which naturally involves spin and orbital degrees of freedom. The ensuing poor-man scaling equations are solved and the Kondo temperature is calculated.

Coqblin-Schrieffer model for an ultracold gas of ytterbium atoms with metastable state

Motivated by the impressive recent advance in manipulating cold ytterbium atoms we explore and substantiate the feasibility of realizing the Coqblin-Schrieffer model in a gas of cold fermionic

Model for overscreened Kondo effect in ultracold Fermi gas

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Two-channel orbital Kondo effect in a quantum dot with SO(n) symmetry

Yb atoms. Making use of different AC polarizabillity of the electronic ground state (electronic configuration

Unconventional mechanisms of resonance tunneling through complex quantum dots

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Kondo effect in systems with dynamical symmetries

) and the long lived metastable state (electronic configuration

Kondo effect in molecules with strong correlations

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