Bath-state-dependent quantum phase on a single NV center

The central spin model is useful for developing qubits as sensors of environmental noise and protecting qubits from decoherence. In both noise spectroscopy and dynamical decoupling protocols, the central qubit is actively controlled. However, the qubit-bath interaction may enable changes in the qubit state to trigger changes in the bath state, ultimately modifying the evolution of the qubit [1]. Here, we experimentally observe the self-interaction of the electron spin of the nitrogen vacancy (NV) center in diamond mediated by a bath of polarized ¹³C nuclear spins. We use the modified NV center evolution to detect the polarization of the bath during phase-resolved Hahn echo sequences. These techniques may assist in improving nuclear spin hyperpolarization, investigating the nature of environmental noise and preparing high-fidelity memory states.

[1] Y.-X. Wang and A. A. Clerk, Nat. Commun. 12, 6528 (2021).