Time-dependent transport through quantum-impurity systems with Kondo resonance

Abstract

We investigate the time-dependent transport properties of single and double quantum-impurity systems based on the hierarchical equations of motion (HEOM) approach. In the Kondo regime, the dynamical current oscillates with time in both cases due to the temporal coherence of electrons tunneling through the device, which shares the same mechanism as the single-level resonance without e-e interactions, but shows some different characteristics. For single quantum-impurity systems, the temperature T has an inhibitory effect on the oscillations of dynamic current through its suppression of the Kondo effects. The amplitude of the current oscillations is attenuated by the e-e interaction U in the Kondo regime. The frequency of the current oscillations is found almost independent of T and U. For parallel-coupling double quantum-impurity systems, the oscillation of the current shows similar behavior to the single one, but with two-to-three times larger amplitudes. At the limit of small interimpurity coupling the oscillation of the current exhibits enhanced characters, while it is weakened at the other limit.

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

“…3(a). With the increase of the inter-dot coupling, the single peak of A 1 (ω)/A 3 (ω) grows slightly higher due to the "t-enhanced Kondo phenomenon" (figure not shown) [30]. Further increasing t to t > 0.3 meV distinctly changes the Kondo features.…”

Performance of theT-matrix based master equation for Coulomb drag in double quantum dots

“…The numerical implementation of the HEOM formalism, usually termed HEOM, can capture the combined effects of system-reservoir dissipation, many-body interactions, and non-Markovian memory in a nonperturbative manner. The HEOM approach is applicable to both static and dynamic properties of diverse quantum impurity systems [55][56][57][58][59][60][61][62][63][64][65]. Moreover, it has also been combined with the density-functional theory to study the correlated electronic structure of adsorbed magnetic molecules [66][67][68].…”

Reappearance of the Kondo effect in serially coupled symmetric triple quantum dots

“…The different transport processes can be handled in a unified manner. It is applicable to a wide range of system parameters without additional derivation and programming efforts and can characterize both static and transient electronic properties of strongly correlated system [32]. The reduced density matrix of the quantum dots system ρ (0) (t) ≡ tr res ρ total (t) and a set of auxiliary density matrices {ρ (n) j1···jn (t); n = 1, · · · , L} are the basic variables in HEOM.…”