Spectroscopy of composite solid-state spin environments for improved metrology with spin ensembles

TL;DR

This study uses coherent spectroscopy to analyze the spin environment of NV centers in diamond, revealing ways to significantly enhance their metrological performance by understanding and controlling spin bath dynamics.

Contribution

It introduces a spectroscopic method to characterize and suppress spin bath dynamics, leading to improved figures of merit for solid-state quantum sensors.

Findings

NV FOM can be nearly an order of magnitude larger than previous results

Identification of a new suppression mechanism involving nuclear spin baths

Results approach the performance of atomic systems in solid-state platforms

Abstract

For precision coherent measurements with ensembles of quantum spins the relevant Figure-of-Merit (FOM) is the product of polarized spin density and coherence lifetime, which is generally limited by the dynamics of the spin environment. Here, we apply a coherent spectroscopic technique to characterize the dynamics of the composite solid-state spin environment of Nitrogen-Vacancy (NV) centers in room temperature diamond. For samples of very different NV densities and impurity spin concentrations, we show that NV FOM values can be almost an order of magnitude larger than previously achieved in other room-temperature solid-state spin systems, and within an order of magnitude of the state-of-the-art atomic system. We also identify a new mechanism for suppression of electronic spin bath dynamics in the presence of a nuclear spin bath of sufficient concentration. This suppression could inform efforts to further increase the FOM for solid-state spin ensemble metrology and collective quantum information processing.