High-fidelity initialization of long-lived quantum dot hole spin qubits by reduced fine-structure splitting

TL;DR

This paper presents a method for initializing long-lived hole spin qubits in quantum dots with high speed and fidelity by reducing fine-structure splitting, enabling better quantum information processing.

Contribution

The authors demonstrate a novel initialization scheme for hole spin qubits using low fine-structure splitting in quantum dots, achieving fast, high-fidelity, and long-lived qubits.

Findings

Achieved 100 ps initialization time with >99% fidelity.

Extended qubit lifetime with 2T₁ > 10 ns.

Enhanced fidelity via optical Stark effect tuning.

Abstract

We demonstrate an on-demand hole spin qubit initialization scheme meeting four key requirements of quantum information processing: fast initialization (1/e ~ 100 ps), high fidelity (F > 99%), long qubit lifetime $(2T_{1}>T_{2}^{*}\simeq10\:\mathrm{ns})$, and compatibility with optical coherent control schemes. This is achieved by rapidly ionizing an exciton in an InGaAs quantum dot with very low fine-structure splitting at zero magnetic field. Furthermore, we show that the hole spin fidelity of an arbitrary quantum dot can be increased by optical Stark effect tuning of the fine-structure splitting close to zero.