Multilevel coherences in quantum dots

Abstract

We study transport through strongly interacting quantum dots with N energy levels that are weakly coupled to generic multichannel metallic leads. In the regime of coherent sequential tunneling, where level spacing and broadening are of the same order but small compared to temperature, we present a unified SU(N)-invariant form of the kinetic equation for the reduced density matrix of the dot and the tunneling current. This is achieved by introducing the concept of flavor polarization for the dot and the reservoirs and splitting the kinetic equation in terms of flavor accumulation, anisotropic flavor relaxation, and exchange-field-and detuning-induced flavor rotation. In particular, we identify the exchange field as the cause of negative differential conductance at offresonance bias voltages appearing in generic quantum-dot models. To illustrate the notion of flavor polarization, we analyze the nonlinear current through a triple-quantum-dot device.

Pseudospin resonances reveal synthetic spin-orbit interaction

“…In the framework of Eqs. ( 36)-( 38), vectorial resonance conditions can be formulated similarly to the ansatz in [11,27]:…”

“…(41) in determining the resonance positions reduces as the angle θ is chosen farther away from antiparallel alignment. In contrast to the resonance conditions formulated in [11] and in [27], we choose Eq. ( 41), where the drain and the source equally participate, since it matches the numerical resonances on a broader parameter range.…”

“…In order to gain a clearer physical understanding of the numerical results, we also set up a minimal model in the CST regime [27]. To this purpose, we start from Eq.…”

“…Valleytronics concerns instead the manipulation of a state living in a twofold orbitally degenerate space. Very recently, this concept has been further extended to flavortronics [27], for interacting systems with n-fold degeneracy.…”

Precession of entangled spin and pseudospin in double quantum dots

“…Exchange fields, generated by the electronic fluctuations, characterize, in general, the dynamics of degenerate, interacting quantum system weakly coupled to the leads [5][6][7][8][9]. Those electronic fluctuations lead to a renormalization of system energies [10,11] which -under the * christoph.rohrmeier@ur.de right circumstances -also drive precession dynamics of the system degrees of freedom, similarly to external magnetic fields [12].…”