Harvard Condensed Matter Theory Seminars

Nayana Shah, University of Cologne

Non-Equilibrium and Non-Fermi-liquid Kondo Physics in Quantum Dots
The developments in quantum dot devices during the last decade have provided a highly tunable laboratory for the realization of Kondo physics, which is one of the best understood prototypes for strong correlation physics. It has now become possible to explore and access old as well as new fixed points with unprecedented level of control. Though theoretically well understood, a clear experimental realization of the two-channel non-Fermi-liquid fixed point has remained elusive so far. By presenting our recent proposal for a quantum dot set-up, I will discuss how it might be possible to use the Coulomb blockade effect to tune to this fixed point, and detect it via the capacitance line-shape for which we have made precise predictions. On the other hand, experiments on quantum dots have led to new theoretical questions of fundamental nature such as the fate of the Kondo effect in the presence of applied bias voltage. Motivated by recent experiments, I will present our results for the non-equilibrium conductance of a quantum dot connected to three leads which displays the characteristic splitting of the Kondo resonance and the effects of decoherence. On the way, I will illustrate the key features involved in generalizing the perturbative renormalization framework to non-equilibrium and the question of strong versus weak coupling.

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