# Electric-field control and noise protection of the flopping-mode spin qubit

## TL;DR

This paper introduces a new 'flopping-mode' mechanism for spin qubits that enhances electric control and noise protection by leveraging charge delocalization and sweet spots, improving qubit fidelity.

## Contribution

It proposes and analyzes the flopping-mode spin qubit, demonstrating optimized control and noise suppression through theoretical modeling of the double quantum dot system.

## Key findings

- Maximized electronic dipole moment in the flopping-mode regime.
- Identification of a controllable sweet spot with suppressed charge noise coupling.
- Reduced sensitivity to charge fluctuations with a longitudinal magnetic field gradient.

## Abstract

We propose and analyze a novel "flopping-mode" mechanism for electric dipole spin resonance based on the delocalization of a single electron across a double quantum dot confinement potential. Delocalization of the charge maximizes the electronic dipole moment compared to the conventional single dot spin resonance configuration. We present a theoretical investigation of the flopping-mode spin qubit properties through the crossover from the double to the single dot configuration by calculating effective spin Rabi frequencies and single-qubit gate fidelities. The flopping-mode regime optimizes the artificial spin-orbit effect generated by an external micromagnet and draws on the existence of an externally controllable sweet spot, where the coupling of the qubit to charge noise is highly suppressed. We further analyze the sweet spot behavior in the presence of a longitudinal magnetic field gradient, which gives rise to a second order sweet spot with reduced sensitivity to charge fluctuations.