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Bias-induced chiral current and geometrical blockade in triangular triple quantum dot
摘要： We theoretically investigate the quantum transport properties of a triangular triple quantum dot (TTQD) ring connected to two reservoirs by an analytical derivation and an accurate hierarchical equations-of-motion calculation. We initially demonstrate a bias-induced chiral current under zero magnetic field caused by the coupling between the spin gauge field and spin current in a nonequilibrium TTQD that induces a scalar spin chirality, which lifts the chiral degeneracy and the time inversion symmetry. The chiral current oscillates with the bias within the Coulomb blockade regime, suggesting that the chiral spin qubit can be controlled by purely electrical manipulations. Then, the geometrical blockade of the transport current due to the localization of chiral states is elucidated by spectral function analysis.
关键词： triple quantum dot,quantum transport,chiral current,geometrical blockade
更新于2025-09-23 15:21:01
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Scenarios of local spectral property and multifunctional spin selecting for a triple quantum dot molecule: How do the bonding and antibonding orbitals contribute to the spin currents?
摘要： Molecular electronic device is considered as a promising candidate for next generation electronic component, where the basic challenge involves understanding the charge and spin transports through molecular objects. In this paper, with the help of the sophisticated numerical renormalization group technique, we study theoretically the spin selective transport in a parallel triple quantum dot molecular device pierced by a local magnetic field along z axis. Based on simplified parameters of real molecular system, we find such device acts as a multi-functional spin selector when the inter-molecule tunneling couplings are asymmetric, including two 100% polarized spin-up summits, and one 100% spin-down summit in the linear conductance. We show in detail the local density of states for the bonding and anti-boding orbitals, and attribute the spin selection to the orbital polarized Coulomb blockade effect. We demonstrate our numerical results are consistent with those estimated by the analytical techniques, including the Friedel sum rule and the energy level crossings of the isolated orbitals.
关键词： Coulomb blockade effect,Multifunctional spin selector,Triple quantum dot molecule,Numerical renormalization group technique,Molecular electronics device
更新于2025-09-12 10:27:22