Robust single-qubit gates by composite pulses in three-level systems

TL;DR

This paper develops composite pulse sequences for robust single-qubit gates in three-level systems, enhancing fidelity against systematic errors and enabling more reliable quantum information processing.

Contribution

It introduces optimized composite pulse sequences for three-level systems, improving robustness of single-qubit gates beyond previous methods.

Findings

Three-pulse sequence partially cancels errors but not all first-order errors.

Increasing pulses ($N>3$) enhances robustness in all directions.

Demonstrates improved quantum information transfer using these sequences.

Abstract

Composite pulses are an efficient tool for robust quantum control. In this work, we derive the form of the composite pulse sequence to implement robust single-qubit gates in a three-level system, where two low-energy levels act as a qubit. The composite pulses can efficiently cancel the systematic errors up to a certain order. We find that the three-pulse sequence cannot completely eliminate the first order of systematic errors, but still availably makes the fidelity resistant to variations in a specific direction. When employing more pulses in the sequence ($N>3$), the fidelity can be insensitive to the variations in all directions and the robustness region becomes much wider. Finally we demonstrate the applications of composite pulses in quantum information processing, e.g., robust quantum information transfer between two qubits.