The electronic conductance at zero temperature through a quantum wire with side-connected asymmetric quantum ring (as a scatter system) is theoretically studied using the non-interacting Hamiltonian Anderson tunneling method. In this paper we concentrate on the configuration of the quantum dot rings. We show that the asymmetric structure of QD-scatter system strongly influences the amplitude an...

We report coherent operation of a singlet-triplet qubit controlled by the spatial arrangement of two confined electrons in an adjacent double quantum dot that is electrostatically coupled to the qubit. This four-dot system is the specific device geometry needed for two-qubit operations of a two-electron spin qubit. We extract the strength of the capacitive coupling between qubit and adjacent do...

We quantitatively describe the main features of the magnetically induced conductance modulation of a Kondo quantum dot-or chessboard pattern-in terms of a constant-interaction double quantum dot model. We show that the analogy with a double dot holds down to remarkably low magnetic fields. The analysis is extended by full 3D spin density functional calculations. Introducing an effective Kondo c...

A noninteracting quantum-dot arrays side coupled to a quantum wire is studied. Transport through the quantum wire is investigated by using a noninteracting Anderson tunneling Hamiltonian. The conductance at zero temperature develops an oscillating band with resonances and antiresonances due to constructive and destructive interference in the ballistic channel, respectively. Moreover, we have fo...

The transport spectrum of a strongly tunnel-coupled one-electron double quantum dot electrostatically defined in a GaAs/AlGaAs heterostructure is studied. At finite source-drain-voltage we demonstrate the unambiguous identification of the symmetric ground state and the antisymmetric excited state of the double well potential by means of differential conductance measurements. A sizable magnetic ...

We show that a double quantum-dot system made of diluted magnetic semiconductor behaves unlike usual molecules. In a semiconductor double quantum dot or in a diatomic molecule, the ground state of a single carrier is described by a symmetric orbital. In a magnetic material molecule, new ground states with broken symmetry can appear due the competition between the tunnelling and magnetic polaron...

application of quantum-dot is a promising technology for implementing digital systems at nano-scale.  quantum-dot cellular automata (qca) is a system with low power consumption and a potentially high density and regularity. also, qca supports the new devices with nanotechnology architecture. this technique works based on electron interactions inside quantum-dots leading to emergence of quantum ...

We report an experimental demonstration of a functional cell for quantum-dot cellular automata ~QCA!, a transistorless approach to implement logic functions. The four-dot QCA cell is defined by a pair of series-connected, capacitively coupled input and output double dots. We demonstrate that, at low temperature, an electron switch in the input double dot induces an opposite electron switch in t...