Irreversible decoherence of dipole interacting nuclear spins coupled with a phonon bath

TL;DR

This paper presents a first-principles theoretical analysis of how low-frequency phonons induce irreversible decoherence in a chain of nuclear spins in a solid, highlighting the impact on multi-spin coherences.

Contribution

It introduces a spin-boson model for adiabatic decoherence of nuclear spins coupled to phonons, emphasizing the role of spin state complexity in coherence degradation.

Findings

Phonon coupling destroys spin coherence in the adiabatic regime.

Decoherence efficiency increases with the number of active spins involved.

The mechanism significantly affects multi-spin coherences in solid-state systems.

Abstract

We report a first-principle theoretical study of the adiabatic decoherence undergone by a nuclear spin system in a solid, coupled to the phonon field through the dipolar interaction. The calculations are performed for a chain of weakly interacting 1/2-spin pairs, considered as an open quantum system in contact with a bosonic heat bath. By incorporating to the whole system Hamiltonian the fluctuations of the local dipolar energy produced by low frequency phonons, and assuming that this low energy fluctuations are adiabatic, we find that the spin dynamics can be described in closed form through a spin-boson model. The obtained results show that the coupling with the phonons destroy the spin coherence, and the efficiency of the process significantly depends on the complexity of the involved spin states. By using realistic values for the various parameters of the model, we conclude that this mechanism can be particularly efficient to degrade multi-spin coherences, when the number of `active' spins involved in a given coherence is high. In this way, we show that the spin coherence in the adiabatic regime can be noticeably affected by this mechanism.