Decoherence by electromagnetic fluctuations in double-quantum-dot charge qubits

TL;DR

This paper analyzes how electromagnetic fluctuations cause decoherence in double-quantum-dot charge qubits, estimating relaxation times and showing that other decoherence sources are more significant.

Contribution

It introduces an effective circuit model to evaluate electromagnetic fluctuation correlations and estimates qubit relaxation times, highlighting the dominant role of other decoherence mechanisms.

Findings

Estimated T1 and T2 relaxation times are longer than experimental values.

Electromagnetic fluctuations alone cannot account for observed decoherence.

Other sources of decoherence are likely more influential in these systems.

Abstract

We discuss decoherence due to electromagnetic fluctuations in charge qubits formed by two lateral quantum dots. We use an effective circuit model to evaluate correlations of voltage fluctuations in the qubit setup. These correlations allows us to estimate energy (T1) and phase (T2) relaxation times of the the qubit system. Our theoretical estimate of the quality factor due to dephasing by electromagnetic fluctuations yields values much higher than those found in recent experiments, indicating that other sources of decoherence play a dominant role.