# High-fidelity gate set for exchange-coupled singlet-triplet qubits

## TL;DR

This paper develops a high-fidelity control method for exchange-coupled singlet-triplet qubits in semiconductor quantum computers, addressing realistic hardware constraints and noise, achieving near-perfect gate fidelities in GaAs and Si.

## Contribution

It introduces optimized control pulses for exchange-coupled singlet-triplet qubits considering realistic hardware and noise, significantly improving gate fidelities.

## Key findings

- Achieves 99.90% two-qubit gate fidelity in GaAs.
- Achieves 99.99% two-qubit gate fidelity in Si.
- Demonstrates robustness of control pulses under realistic noise spectra.

## Abstract

In order to enable semiconductor-based quantum computing with many qubits, issues like residual interqubit coupling and constraints from scalable control hardware need to be tackled to retain the high gate fidelities demonstrated in current single-qubit devices. Here, we focus on two exchange-coupled singlet-triplet spin qubits, considering realistic control hardware as well as Coulomb and exchange coupling that cannot be fully turned off. Using measured noise spectra, we optimize realistic control pulses and show that two-qubit (single-qubit) gate fidelities of 99.90\% ($\ge 99.69\%$) can be reached in GaAs, while 99.99\% ($\ge 99.95\%$) can be achieved in Si.