Quantum measurement of hyperfine interaction in nitrogen-vacancy center

TL;DR

This paper introduces a quantum measurement protocol for hyperfine interaction in nitrogen-vacancy centers that achieves high precision approaching the quantum limit without requiring nuclear spin preparation.

Contribution

The proposed protocol estimates hyperfine interaction with increasing precision, bypassing the need for nuclear spin state preparation and outperforming the standard quantum limit under realistic conditions.

Findings

Protocol approaches quantum metrology limit

Does not require nuclear spin state preparation

Outperforms standard quantum limit with errors

Abstract

We propose an efficient quantum measurement protocol for the hyperfine interaction between the electron spin and the $^{15}$N nuclear spin of a diamond nitrogen-vacancy center. In this protocol, a sequence of quantum operations of successively increasing duration is utilized to estimate the hyperfine interaction with successively higher precision approaching the quantum metrology limit. This protocol does not need the preparation of the nuclear spin state. In the presence of realistic operation errors and electron spin decoherence, the overall precision of our protocol still surpasses the standard quantum limit.