C Nuclei at the Low Temperature and High Magnetic Field Regime*

Large interacting spin systems approaching the thermodynamic regime have proven to be an interesting platform for a variety of applications such as quantum sensing and studies of spin transport. Hyperpolarized ¹³C nuclei in diamond are an excellent candidate for such experiments because of their several-second long coherence time which can be extended to 90s using a Floquet driving pulse sequence [1]. We have shown that this system can be used in high-field magnetometry and studies of spin transport [2], [3]. In these experiments, the ¹³C nuclei are first hyperpolarized via NV centers at low field and then shuttled to higher magnetic field to perform experiments with high chemical resolution.

Although the NV centers are used as a polarization source for the ¹³C, during experiments, NV centers and P1 centers act as relaxation sinks [3]. At extremely low temperatures and high magnetic fields, simple Boltzmann statistics show that electrons (P1 centers and NV centers) will be over 99% polarized. This has also been verified experimentally [4]. Within this work, we build new instrumentation which can perform experiments on hyperpolarized ¹³C in diamond at low temperatures and high magnetic fields (~9T). We expect that the mechanisms of relaxation stemming from nearby P1 centers and NV centers will be suppressed and that there will be an extremely long-lived state of the bulk ¹³C nuclei. This will open a pathway to new and exciting regimes of quantum science where we can perform experiments over extremely long time scales.