# Hyperpolarized relaxometry based nuclear T1 noise spectroscopy in hybrid diamond quantum registers

## TL;DR

This study uses hyperpolarization and field cycling to map nuclear spin relaxation in diamond, revealing how electronic spin baths influence 13C lifetimes across different magnetic fields, with implications for quantum memory and imaging.

## Contribution

It introduces a hyperpolarized relaxometry method over a wide field range to identify relaxation channels in diamond quantum systems, highlighting the role of P1 centers.

## Key findings

- 13C lifetimes increase with magnetic field up to 100mT
- Dominant relaxation channel involves coupling to P1 electronic spins
- Hyperpolarization enables million-fold measurement time savings

## Abstract

Understanding the origins of spin lifetimes in hybrid quantum systems is a matter of current importance in several areas of quantum information and sensing. Methods that spectrally map spin relaxation processes provide insight into their origin and can motivate methods to mitigate them. In this paper, using a combination of hyperpolarization and precision field cycling over a wide range (1mT-7T), we map frequency dependent relaxation in a prototypical hybrid system of 13C nuclear spins in diamond coupled to Nitrogen Vacancy centers. Nuclear hyperpolarization through the optically pumped NV electrons allows signal time savings for the measurements exceeding million-fold over conventional methods. We observe that 13C lifetimes show a dramatic field dependence, growing rapidly with field up to 100mT and saturating thereafter. Through a systematic study with increasing substitutional electron (P1 center) concentration as well as 13C enrichment levels, we identify the operational relaxation channels for the nuclei in different field regimes. In particular, we demonstrate the dominant role played by the 13C nuclei coupling to the interacting P1 electronic spin bath. These results pave the way for quantum control techniques for dissipation engineering to boost spin lifetimes in diamond, with applications ranging from engineered quantum memories to hyperpolarized 13C imaging.