Dynamic sweet spot of driven flopping-mode spin qubits in planar quantum dots

TL;DR

This paper investigates how off-resonant driving in planar double quantum dot spin qubits can mitigate electric noise effects, revealing a dynamic sweet spot that enhances quantum gate fidelity and coherence.

Contribution

It introduces the concept of a dynamic sweet spot in driven flopping-mode spin qubits, demonstrating noise mitigation and improved fidelity through off-resonant driving.

Findings

Off-resonant driving reduces charge noise impact.

A dynamic sweet spot improves gate fidelity.

Potential for a second-order dynamic sweet spot.

Abstract

Semiconductor quantum dots with confined electron or hole spins show promise for quantum information processing as they allow for efficient electric field-driven qubit manipulation. However, their susceptibility to electric noise poses a challenge that may hinder the effectiveness of these qubits. Here, we explore the impact of electric noise on a planar double quantum dot (DQD) spin qubit under the influence of AC gates applied to the dot levels, focusing on the flopping-mode spin qubit with spin-orbit interaction. We employ a rotating wave approximation within a time-dependent effective Hamiltonian to derive analytic expressions for the Rabi frequency of spin qubit oscillations with a single electron or hole in a DQD. We find that driving the qubit off-resonantly effectively mitigates the influence of charge noise, leading to a manifestation of a dynamic sweet spot. The proposed mode of operation notably improves the fidelity of quantum gates, particularly within specific ranges of drive parameters and detuning during qubit manipulation. Furthermore, our study unveils the potential of inducing a second-order dynamic sweet spot, a phenomenon tunable by drive and DQD parameters. Understanding the importance of driving qubits off-resonantly is essential for developing high-coherence planar DQD spin qubits, both for electrons in silicon and holes in germanium.