Tunable Gyromagnetic Augmentation of Nuclear Spins in Diamond

Nuclear spins in solids have attracted interest as a qubit platform, as they exhibit long coherence times due to an intrinsically weak coupling to magnetic fields. The reduced coupling to magnetic noise, however, comes with concomitantly weaker coupling to control fields, which leads to slow and error prone gate operations. For nuclear spins that are hyperfine-coupled to nearby electrons, such as the P1 defect in diamond, application of a magnetic field mixes electron spin state characteristics into the nuclear spin state. In this talk, I will present our work demonstrating rapid control of nuclear spins, which are well isolated from external fields, through magnetic-field induced augmentation.

Our experiments use an ensemble of nitrogen-vacancy (NV) centers to detect optically-dark paramagnetic defects (P1 centers) in diamond. Using spin-echo interferometry to measure the magnetic signatures of P1 spins, we demonstrate that gyromagnetic augmentation can be tuned by variation of the strength of an external magnetic field. We identify that at low magnetic fields, we can perform rapid quantum control of the P1 nuclear spin state at MHz Rabi frequencies, which are up to 5000 times faster than those measured at higher magnetic fields and are comparable to those of the P1 and NV electron spin. I will also report on experiments in which we examine the coherence of the P1 electron and nuclear spin as the magnetic field is varied and the consequences of gyromagnetic augmentation on the coherent properties of the system.