# Autonomous Calibration of Single Spin Qubit Operations

## TL;DR

This paper demonstrates fully autonomous calibration of single spin qubit operations in diamond using closed-loop optimization, achieving high fidelities rapidly and with minimal human intervention, advancing quantum nanotechnology capabilities.

## Contribution

It introduces a method for autonomous calibration of qubit operations via closed-loop optimization, improving precision and efficiency in quantum control.

## Key findings

- Achieved up to 1.00 fidelity for spin population inversion within minutes.
- Achieved up to 0.98 fidelity for Hadamard gate within hours.
- Demonstrated robustness of calibration at room temperature.

## Abstract

Fully autonomous precise control of qubits is crucial for quantum information processing, quantum communication, and quantum sensing applications. It requires minimal human intervention on the ability to model, to predict and to anticipate the quantum dynamics [1,2], as well as to precisely control and calibrate single qubit operations. Here, we demonstrate single qubit autonomous calibrations via closed-loop optimisations of electron spin quantum operations in diamond. The operations are examined by quantum state and process tomographic measurements at room temperature, and their performances against systematic errors are iteratively rectified by an optimal pulse engineering algorithm. We achieve an autonomous calibrated fidelity up to 1.00 on a time scale of minutes for a spin population inversion and up to 0.98 on a time scale of hours for a Hadamard gate within the experimental error of 2%. These results manifest a full potential for versatile quantum nanotechnologies.