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

Abstract

Long-range interactions in triple quantum dots (TQDs) in Kondo regime are investigated by accurately solving the three-impurity Anderson model. For the occupation configuration of (N1, N2, N3) = (1, 0, 1), a long-range antiferromagnetic exchange interaction (JAF) is demonstrated and induces a continuous phase transition from the separated Kondo singlet (KS) to the long-range spin singlet (LSS) state between edge dots. The expression of JAF is analytically derived and numerically verified, according to which JAF can be conveniently manipulated via gate control of the detuning energy. The long-range entanglement of Kondo clouds are proved to be quite robust at strong inter-dot coupling limit. Under equilibrium condition, it induces an unexpected peak in the spectral function of the middle dot whose singly occupied level keeps much higher than the Fermi level. Under nonequilibrium condition, higher inter-dot tunneling barrier induces an anomalous enhancement of current. These novel features can be observed in routine experiments.

Current-induced bond rupture in single-molecule junctions

“…In this approach, the electrons are treated fully quantum-mechanically within the numerically exact hierarchical quantum master equation (HQME) approach. 28,[61][62][63][64][65][66][67][68][69][70][71][72][73][74][75] The nuclear motion, on the other hand, is described by the classical Ehrenfest method. [76][77][78][79][80][81][82][83][84] The use of the HQME method allows to solve the transport problem for a dissociative system within the Ehrenfest approximation without further approximation, thus extending previous related methodologies.…”

Current-induced dissociation in molecular junctions beyond the paradigm of vibrational heating: The role of antibonding electronic states

“…The approach was originally developed by Tanimura and Kubo in the context of relaxation dynamics, 67,68 and was later on applied by various groups to describe transport in quantum systems. 31,47,[69][70][71][72][73][75][76][77][78][79][80][81][82] For a detailed account of the HQME method, we refer to Refs. 71, 76, 86, and 87. Within the HQME framework, the influence of the leads, as described by Eqs.…”

“…This approach, which we proposed recently [66], is based on the numerically exact hierarchical quantum master equation (HQME) approach. 31,[67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83] Moreover, the framework uses a discrete variable representation (DVR) for the nuclear DOF, thus allowing for general potential energy surfaces (PESs) to be represented adequately. 84,85 Here, we provide a comprehensive account of the method and apply it to study current-induced dissociation for a wide range of model parameters, ranging from the nonadiabatic regime of weak molecule-lead coupling to the adiabatic case of strong coupling.…”

Transient dynamics of a quantum-dot: From Kondo regime to mixed valence and to empty orbital regimes

“…In this paper, the single-impurity Anderson model is accurately solved by the hierarchical equations of motion (HEOM) approach. The HEOM established based on the Feynman-Vernon path-integral formalism is potentially useful for treating the quantum-impurity systems, here the system-bath correlations are fully take into consideration [34,36,37]. This formalism is also valuable for addressing both static and transient electronic properties of strongly correlated system.…”