State Initialization of a Hot Spin Qubit in a Double Quantum Dot by Measurement-Based Quantum Feedback Control

TL;DR

This paper presents a measurement-based quantum feedback protocol that enhances the speed and fidelity of spin qubit initialization in double quantum dots, crucial for scalable quantum computing.

Contribution

It introduces a novel feedback protocol that pre-sets and improves qubit initialization fidelity and robustness, even at high temperatures.

Findings

Faster qubit initialization with higher fidelity.

Effective at high temperatures for scalable quantum computing.

Pre-sets the desired fidelity for more deterministic initialization.

Abstract

A measurement-based quantum feedback protocol is developed for spin state initialization in a gate-defined double quantum dot spin qubit coupled to a superconducting resonator. The protocol improves qubit state initialization as it is able to robustly prepare the spin in shorter time and reach a higher fidelity, which can be pre-set. Being able to pre-set the fidelity aimed at is a highly desired feature enabling qubit initialization to be more deterministic. The protocol developed herein is also effective at high temperatures, which is critical for the current efforts towards scaling up the number of qubits in quantum computers.