Time-dependent single-electron transport through quantum dots

TLDR

Electron–phonon interaction and spin–orbit coupling are key dissipation mechanisms in quantum dot systems. The study describes time‑dependent single‑electron transport through quantum dots in the Coulomb blockade regime. The authors model coherent dynamics of a single‑charge qubit in a double quantum dot, controlling decoherence via applied voltage while accounting for electron‑phonon coupling and background fluctuations, and analyze energy‑relaxation of orbital and spin states with charge‑detection measurements for qubit read‑out. Charge‑detection measurements enable statistical analysis of single‑electron tunnelling transitions and provide a sensitive qubit read‑out device.

Abstract

We describe time-dependent single-electron transport through quantum dots in the Coulomb blockade regime. Coherent dynamics of a single charge qubit in a double quantum dot is discussed with full one-qubit manipulation. Strength of decoherence is controlled with the applied voltage, but uncontrolled decoherence arises from electron–phonon coupling and background fluctuations. Then energy-relaxation dynamics is discussed for orbital and spin degree of freedom in a quantum dot. The electron–phonon interaction and spin–orbit coupling can be investigated as the dissipation problem. Finally, charge detection measurement is presented for statistical analysis of single-electron tunnelling transitions and for a sensitive qubit read-out device.