Noise Analysis of Qubits Implemented in Triple Quantum Dot Systems in a Davies Master Equation Approach

TL;DR

This paper investigates how external noise affects qubits in triple quantum dot systems using a Davies master equation, comparing two qubit realizations and analyzing initial error probabilities.

Contribution

It introduces a detailed noise model for triple quantum dot qubits and compares subspace and subsystem implementations using a Davies master equation approach.

Findings

Initial time evolution decouples from long-term dynamics

Error probabilities for dephasing, relaxation, and leakage are quantified

Davies model simplifies the noise analysis and error estimation

Abstract

We analyze the influence of noise for qubits implemented using a triple quantum dot spin system. We give a detailed description of the physical realization and develop error models for the dominant external noise sources. We use a Davies master equation approach to describe their influence on the qubit. The triple dot system contains two meaningful realizations of a qubit: We consider a subspace and a subsystem of the full Hilbert space to implement the qubit. We test the robustness of these two implementations with respect to the qubit stability. When performing the noise analysis, we extract the initial time evolution of the qubit using a Nakajima-Zwanzig approach. We find that the initial time evolution, which is essential for qubit applications, decouples from the long time dynamics of the system. We extract probabilities for the qubit errors of dephasing, relaxation and leakage. Using the Davies model to describe the environment simplifies the noise analysis. It allows us to construct simple toy models, which closely describe the error probabilities.