Spin coherence in strongly coupled spin baths in quasi-two-dimensional layers

TL;DR

This study explores how spin coherence times in diamond layers with nitrogen defects can surpass bulk limits, using a novel cluster-correlation expansion method to understand decoherence mechanisms for quantum technology applications.

Contribution

It introduces a new cluster-correlation expansion approach for strongly-interacting spin baths and demonstrates enhanced coherence times in thin diamond layers.

Findings

Coherence times exceed bulk diamond limits in thin layers.

Hyperfine interactions govern short-time decay behavior.

The new method constrains noise models for quantum devices.

Abstract

We investigate the spin-coherence decay of NV$^-$-spins interacting with the strongly-coupled bath of nitrogen defects in diamond layers. For thin diamond layers, we demonstrate that the spin-coherence times exceed those of bulk diamond, thus allowing to surpass the limit imposed by high defect concentrations in bulk. We show that the stretched-exponential parameter for the short-time spin-coherence decay is governed by the hyperfine interaction in the bath, thereby constraining random-noise models. We introduce a novel method based on the cluster-correlation expansion applied to strongly-interacting bath partitions. Our results facilitate material development for quantum-technology devices.