Dephasing of Exchange-coupled Spins in Quantum Dots for Quantum Computing

TL;DR

This paper reviews progress in understanding and mitigating spin dephasing in exchange-coupled spin qubits within semiconductor quantum dots, crucial for advancing scalable quantum computing.

Contribution

It provides an overview of dephasing mechanisms, gate schemes, and suppression techniques for exchange-coupled spins in quantum dots, aiding high-fidelity quantum gate development.

Findings

Progress on spin dephasing characterization

Methods for suppressing spin dephasing

Insights into high-fidelity quantum gate realization

Abstract

A spin qubit in semiconductor quantum dots holds promise for quantum information processing for scalability and long coherence time. An important semiconductor qubit system is a double quantum dot trapping two electrons or holes, whose spin states encode either a singlet-triplet qubit or two single-spin qubits coupled by exchange interaction. In this article, we report progress on spin dephasing of two exchange-coupled spins in a double quantum dot. We first discuss the schemes of two-qubit gates and qubit encodings in gate-defined quantum dots or donor atoms based on the exchange interaction. Then, we report the progress on spin dephasing of a singlet-triplet qubit or a two-qubit gate. The methods of suppressing spin dephasing are further discussed. The understanding of spin dephasing may provide insights into the realization of high-fidelity quantum gates for spin-based quantum computing.