Relaxation, dephasing, and quantum control of electron spins in double quantum dots

TL;DR

This paper develops a comprehensive theory for electron spin dynamics in double quantum dots, guiding experiments and analyzing relaxation and dephasing mechanisms, demonstrating that electrical control of spin qubits is feasible despite decoherence.

Contribution

It provides a detailed theoretical framework for two-electron spin dynamics in double quantum dots, integrating charge and spin effects to inform quantum control strategies.

Findings

Charge and spin dephasing significantly influence spin dynamics.

Neither charge nor spin dephasing fundamentally limits electrical spin control.

The theory aligns well with recent experimental results.

Abstract

Recent experiments have demonstrated quantum manipulation of two-electron spin states in double quantum dots using electrically controlled exchange interactions. Here, we present a detailed theory for electron spin dynamics in two-electron double dot systems that was used to guide these experiments and analyze experimental results. The theory treats both charge and spin degrees of freedom on an equal basis. Specifically, we analyze the relaxation and dephasing mechanisms that are relevant to experiments and discuss practical approaches for quantum control of two-electron system. We show that both charge and spin dephasing play important roles in the dynamics of the two-spin system, but neither represents a fundamental limit for electrical control of spin degrees of freedom in semiconductor quantum bits.