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

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, progress on the spin dephasing of two exchange-coupled spins in a double quantum dot is reported. First, the schemes of two-qubit gates and qubit encodings in gate-defined quantum dots or donor atoms based on the exchange interaction are discussed. Then, the progress on spin dephasing of a singlet-triplet qubit or a two-qubit gate is reported. The methods of suppressing spin dephasing are further discussed. The understanding of the spin dephasing may provide insights into the realization of high-fidelity quantum gates for spin-based quantum computing.

Automated summary

This article discusses the progress on spin dephasing of two exchange-coupled spins in a double quantum dot, including schemes of two-qubit gates and qubit encodings, as well as methods of suppressing spin dephasing. Understanding spin dephasing may lead to high-fidelity quantum gates for spin-based quantum computing.