Exchange-based CNOT gates for singlet-triplet qubits with spin orbit interaction

TL;DR

This paper presents a scheme for fast CNOT gates in singlet-triplet qubits using exchange and spin orbit interactions, optimizing device geometry and magnetic fields to minimize errors.

Contribution

It introduces a novel implementation of CNOT gates leveraging exchange and spin orbit interactions with optimized device geometry and magnetic field configurations.

Findings

CNOT gates can be executed in a few nanoseconds with realistic GaAs parameters.

Optimal device geometry involves magnetic fields parallel to the spin orbit symmetry axis.

Leakage errors in perpendicular geometry can be suppressed with strong magnetic fields.

Abstract

We propose a scheme for implementing the CNOT gate over qubits encoded in a pair of electron spins in a double quantum dot. The scheme is based on exchange and spin orbit interactions and on local gradients in Zeeman fields. We find that the optimal device geometry for this implementation involves effective magnetic fields that are parallel to the symmetry axis of the spin orbit interaction. We show that the switching times for the CNOT gate can be as fast as a few nanoseconds for realistic parameter values in GaAs semiconductors. Guided by recent advances in surface codes, we also consider the perpendicular geometry. In this case, leakage errors due to spin orbit interaction occur but can be suppressed in strong magnetic fields.