Identifying and decoupling many-body interactions in spin ensembles in diamond

TL;DR

This paper investigates how different control sequences can decouple many-body interactions in diamond spin ensembles, revealing effective methods for isolating specific interactions and improving spin manipulation.

Contribution

It demonstrates that spin locking effectively decouples spins from both dipolar interactions and the environment, and explores optimized pulse sequences for comprehensive interaction suppression.

Findings

Spin locking decouples spins from interactions when driven strongly.

Standard pulsed sequences effectively decouple from the environment.

Specialized sequences can decouple dipolar interactions.

Abstract

We simulate the dynamics of varying density quasi-two-dimensional spin ensembles in solid-state systems, focusing on the nitrogen-vacancy centers in diamond. We consider the effects of various control sequences on the averaged dynamics of large ensembles of spins, under a realistic "spin-bath" environment. We reveal that spin locking is efficient for decoupling spins initialized along the driving axis, both from coherent dipolar interactions and from the external spin-bath environment, when the driving is two orders of magnitude stronger than the relevant coupling energies. Since the application of standard pulsed dynamical decoupling sequences leads to strong decoupling from the environment, while other specialized pulse sequences can decouple coherent dipolar interactions, such sequences can be used to identify the dominant interaction type. Moreover, a proper combination of pulsed decoupling sequences could lead to the suppression of both interaction types, allowing additional spin manipulations. Finally, we consider the effect of finite-width pulses on these control protocols and identify improved decoupling efficiency with increased pulse duration, resulting from the interplay of dephasing and coherent dynamics.