A non-Markovian decoherence theory for double dot charge qubit

TL;DR

This paper introduces an exact non-perturbative theory for electron charge decoherence in double quantum dot systems, accounting for non-Markovian effects and reservoir back-action, providing detailed insights into coherence decay and relaxation times.

Contribution

It extends the Feynman-Vernon influence functional to fermionic environments and derives an exact master equation for double dot charge qubits under general conditions.

Findings

Decoherence dynamics are characterized across Markovian and non-Markovian regimes.

Explicit analysis of relaxation time T1 and dephasing time T2.

Investigation of reservoir back-action and leakage effects on qubit coherence.

Abstract

In this paper, we develop a non-perturbation theory for describing decoherence dynamics of electron charges in a double quantum dot gated by electrodes. We extend the Feynman-Vernon influence functional theory to fermionic environments and derive an exact master equation for the reduced density matrix of electrons in the double dot for a general spectral density at arbitrary temperature and bias. We then investigate the decoherence dynamics of the double dot charge qubit with back-action of the reservoirs being fully taken into account. Time-dependent fluctuations and leakage effects induced from the dot-reservoir coupling are explicitly explored. The charge qubit dynamics from the Markovian to non-Markovian regime is systematically studied under various manipulating conditions. The decay behavior of charge qubit coherence and the corresponding relaxation time $T_1$ and dephasing time $T_2$ are analyzed in details.