Pulse sequences for suppressing leakage in single-qubit gate operations

TL;DR

This paper presents simple pulse sequences that effectively suppress leakage errors in single-qubit gates within three-level systems, addressing a key challenge for fault-tolerant solid-state quantum computing.

Contribution

The authors introduce pulse sequences that mitigate leakage errors without precise knowledge of coupling strengths, applicable to systems like charge quadrupole qubits.

Findings

Pulse sequences significantly reduce leakage errors.

Effective even with unknown coupling strengths.

Applicable to charge quadrupole qubits in quantum dots.

Abstract

Many realizations of solid-state qubits involve couplings to leakage states lying outside the computational subspace, posing a threat to high-fidelity quantum gate operations. Mitigating leakage errors is especially challenging when the coupling strength is unknown, e.g., when it is caused by noise. Here we show that simple pulse sequences can be used to strongly suppress leakage errors for a qubit embedded in a three-level system. As an example, we apply our scheme to the recently proposed charge quadrupole (CQ) qubit for quantum dots. These results provide a solution to a key challenge for fault-tolerant quantum computing with solid-state elements.