Nonequilibrium stabilization of charge states in double quantum dots

Abstract

We analyze the decoherence of charge states in double quantum dots due to cotunneling. The system is treated using the Bloch-Redfield generalized master equation for the Schrieffer-Wolff transformed Hamiltonian. We show that the decoherence, characterized through a relaxation ${\tau }_r$ and a dephasing time ${\tau }_{\varphi }$, can be controlled through the external voltage and that the optimum point, where these times are maximum, is not necessarily in equilibrium. We outline the mechanism of this nonequilibrium-induced enhancement of lifetime and coherence. We discuss the relevance of our results for recent charge qubit experiments.

5 pages, 5 figures

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• Intrinsic phonon decoherence and quantum gates in coupled lateral quantum dot charge qubits
• Tuning of coupling modes in laterally parallel double open quantum dots
• Time-dependent magnetotransport of a wave packet in a quantum wire with embedded quantum dots
• Quantum Dots: Coulomb Blockade, Mesoscopic Fluctuations, and Qubit Decoherence