Microscopic modeling of flopping-mode quantum dot spin qubits

TL;DR

This paper develops a detailed microscopic model for flopping-mode spin qubits, linking device geometry to qubit performance, and explores single- and two-qubit control mechanisms with insights into optimizing qubit interactions.

Contribution

It introduces a flexible modeling framework that captures device-specific features and enables direct mapping from geometry to qubit parameters, improving design and control strategies.

Findings

Simulates electric dipole spin resonance and evaluates Rabi oscillations.

Identifies a tradeoff between fast driving and spectral purity.

Derives exchange interaction considering device geometry and Coulomb effects.

Abstract

We present a flexible microscopic modeling framework for flopping-mode spin qubits that captures the spatial structure of the double-well confinement and magnetic-field-gradient profile beyond conventional low-energy approximations. Our model enables a direct mapping from the device geometry to qubit parameters and metrics. By using this approach, we simulate electric dipole spin resonance-based single-qubit control and evaluate the frequency and spectral purity of the Rabi oscillations across different parameter regimes. Our analysis reveals a fundamental tradeoff between fast electrical driving and clean single-mode Rabi oscillations. We also investigate two-qubit control by considering two capacitively coupled flopping-mode qubits and derive the corresponding exchange interaction with an appropriately restricted configuration interaction treatment. Our approach reveals the interplay between the spatial profile of the double-well confinement, magnetic field gradient, and Coulomb interaction, which together govern the effective exchange coupling strength. Our microscopic modeling framework enables efficient exploration of device geometries and provides design guidelines for optimizing flopping-mode spin qubits in realistic architectures.