Decoherence of two coupled singlet-triplet spin qubits

TL;DR

This paper investigates the decoherence mechanisms of two capacitively coupled singlet-triplet spin qubits, analyzing how charge and field noise affect their coherence and entanglement, and proposes magnetic field gradients as a noise suppression method.

Contribution

It provides a quantitative analysis of two-qubit decoherence and introduces magnetic field gradients as an effective tool to mitigate charge noise effects.

Findings

Decoherence depends on charge and field noise levels.

Magnetic field gradients can suppress charge noise-induced decoherence.

Quantitative maps of decoherence dependence on noise sources.

Abstract

We study a pair of capacitively coupled singlet-triplet spin qubits. We characterize the two-qubit decoherence through two complementary measures, the decay time of coupled-qubit oscillations and the fidelity of entangled state preparation. We provide a quantitative map of their dependence on charge noise and field noise, and we highlight the magnetic field gradient across each singlet-triplet qubit as an effective tool to suppress decoherence due to charge noise.