Spin-Orbit Coupling Fluctuations as a Mechanism of Spin Decoherence

TL;DR

This paper investigates how fluctuations in spin-orbit coupling contribute to spin decoherence, using ESR measurements on a specific compound, and suggests ways to mitigate this decoherence for quantum applications.

Contribution

It introduces a general framework linking spin-orbit fluctuations to decoherence and demonstrates this mechanism through systematic ESR studies on a complex compound.

Findings

Spin-orbit fluctuations are a major source of spin decoherence.

Resonance linewidth anisotropy reveals the impact of spin-orbit interactions.

Sample design and field orientation can mitigate decoherence effects.

Abstract

We discuss a general framework to address spin decoherence resulting from fluctuations in a spin Hamiltonian. We performed a systematic study on spin decoherence in the compound K$_6$[V$_{15}$As$_6$O$_{42}$(D$_2$O)] $\cdot$ 8D$_2$O, using high-field Electron Spin Resonance (ESR). By analyzing the anisotropy of resonance linewidths as a function of orientation, temperature and field, we find that the spin-orbit term is a major decoherence source. The demonstrated mechanism can alter the lifetime of any spin qubit and we discuss how to mitigate it by sample design and field orientation.