Quantum wires and dots induced in a semiconductor by charged metallic filaments separated by an isolating barrier

Abstract

A very thin positively charged metallic filament separated from a surface of a semiconductor ͑S͒ by a thin nontunneling potential barrier ͑B͒ induces a quantum wire (QWr) in the semiconductor at the B / S interface. Single-electron quantum states of this QWr are controlled by a potential (and a charge) of the metallic filament. Two close parallel metallic filaments placed over such a B / S interface form a double-quantum wire with the ground and the first excited electron states, which appear as a result of a symmetric-antisymmetric splitting of the ground electron state in the single QWr. Two crossed metallic filaments, which are parallel to the B / S interface, form a quantum dot with completely localized electron states under the crossing point of the metallic filaments. The analogous crossing of a metallic filament by a pair of close metallic filaments forms a double-quantum dot (DQD). The latter can serve as a two-level qubit cell. Such qubits can be controlled by potentials of three independent metallic filaments inducing the above-mentioned DQD. Besides this "outside" metallic wire control, the DQDs can be connected to each other across the "inside" quantum wires, which have formed these DQDs by crossing.