Electron spin coherence in semiconductors: Considerations for a spin-based solid state quantum computer architecture

TL;DR

This paper theoretically analyzes electron spin coherence times in semiconductor-based quantum computer architectures, highlighting the dominant decoherence mechanisms and providing estimates significantly higher than previous experimental bounds.

Contribution

It offers a detailed theoretical assessment of spin coherence times in silicon and GaAs quantum architectures, emphasizing the impact of spin-spin interactions on decoherence.

Findings

Coherence times range from 1 to 100 microseconds.

Decoherence is mainly due to spectral diffusion and dipolar flip-flops.

Calculated coherence times exceed earlier estimates based on T2* measurements.

Abstract

We theoretically consider coherence times for spins in two quantum computer architectures, where the qubit is the spin of an electron bound to a P donor impurity in Si or within a GaAs quantum dot. We show that low temperature decoherence is dominated by spin-spin interactions, through spectral diffusion and dipolar flip-flop mechanisms. These contributions lead to 1-100 $\mu$s calculated spin coherence times for a wide range of parameters, much higher than former estimates based on $T_{2}^{*}$ measurements.