Noise-protected two-qubit gate using anisotropic exchange interaction

TL;DR

This paper proposes a novel electrically controlled two-qubit gate for Germanium hole spin qubits that leverages anisotropic exchange interaction and composite pulses to enhance fidelity and mitigate charge noise effects.

Contribution

It introduces a new two-qubit gate protocol exploiting anisotropic exchange interaction with a composite pulse scheme for Germanium hole spin qubits.

Findings

Predicted high-fidelity controlled-Z operations

Gate protocol suppresses exchange-energy fluctuations

Pathway toward fault-tolerant quantum processors

Abstract

Hole spin qubits hosted in Germanium quantum dots are promising candidates for scalable quantum computing. The strong spin-orbit interaction can enable fast and all-electrical quantum control. Furthermore, the platform can implement universal quantum control using only baseband signals, which may mitigate the impact of crosstalk and microwave-induced heating. At the same time, spin-orbit interaction gives rise to an anisotropic exchange interaction, whose potential for implementing two-qubit gates has remained largely unexplored. However, the current performance of operating a hole-based quantum computer is mostly limited by dephasing due to low-frequency charge noise. In this work, we propose a novel two-qubit gate protocol for Germanium hole spin qubits operated in the gapless regime. This gate protocol exploits the anisotropic exchange interaction between neighboring spins and utilizes a composite pulse scheme implemented solely through electrical baseband signals. Using this approach, we predict high-fidelity two-qubit controlled-Z operations that can suppress exchange-energy fluctuations, offering a pathway toward fault-tolerant semiconductor quantum processors.