Fano versus Kondo Resonances in a Multilevel “Semiopen” Quantum Dot

Abstract

Linear conductance across a large quantum dot via a single level epsilon(0) with large hybridization to the contacts is strongly sensitive to quasibound states localized in the dot and weakly coupled to epsilon(0). The conductance oscillates with the gate voltage due to interference of the Fano type. At low temperature and Coulomb blockade, Kondo correlations damp the oscillations on an extended range of gate voltage values, by freezing the occupancy of the epsilon(0) level itself. As a consequence, the antiresonances of Fano origin are washed out. The results are in good correspondence with experimental data for a large quantum dot in the semiopen regime.

Entanglement and transport through correlated quantum dot

“…The latter refers to the situation below the Kondo temperature T K ∝ exp(−1/ρ(ǫ F )J K ), above which the conductance at the particle-hole symmetric point ǫ d = −U/2 is depressed and, subsequently, each zero-T Kondo peak displayed on Fig. 2b splits into Coulomb-blockade peaks present in a finite-T situation [15,16,17,18]. In particular, for U = t and V = 0.25t, the exact formula [26] gives the value of T K /t ≈ 3mK/eV, which seems to be in the experimentally accessible range.…”

“…For the more general situation, one can refer to the Numerical Renormalization Group [15] or to the nonequilibrium Keldysh formalism [16]. For example, the former approach was succesfuly generalized to study a molecule with the electron-phonon coupling [17], whereas the latter was adapted for an analysis of the competition between the Fano and the Kondo resonance in various nanodevices [18].…”

Enhanced conductance through side-coupled double quantum dots

“…Fano resonances, which occur due to interference when a discrete level is weakly coupled to a continuous band, were recently observed in experiments on rings with embedded quantum dots 9 and quantum wires with sidecoupled dots 10 . The interplay between Fano and Kondo resonance was investigated using equation of motion 11,12 and slave boson techniques 13 . In this work we study a double quantum dot (DQD) in a side-coupled configuration ( Fig.…”

Zero-Bias Conductance Through Side-Coupled Double Quantum Dots

“…One manifestation of this competition is a two stage Kondo effect (Hofstetter and Schoeller, 2003). Experimentally, it manifests itself as a sharp drop in the conductance vs. gate voltage (van der Wiel et al, 2002).…”

“…It has been recently observed in experiments on rings with embedded quantum dots (Kobayashi et al, 2002) and quantum wires with side-coupled dots (Kobayashi et al, 2004). The interplay between Fano and Kondo resonance was investigated using equation of motion (Bulka and Stefanski, 2001;Stefanski et al, 2004) and Slave boson techniques (Lara et al, 2004).…”