Quantum state tomography of a single electron spin in diamond with Wigner reconstruction

TL;DR

This paper demonstrates the experimental reconstruction of the Wigner function for a single electron spin in diamond, enabling detailed quantum state analysis at room temperature and potential extension to multi-qubit systems.

Contribution

It introduces a method for Wigner function reconstruction of a single spin qubit in diamond, providing a new tool for quantum state tomography at room temperature.

Findings

Successfully reconstructed the Wigner function of a single NV center spin.

Accurately characterized quantum state dynamics during dephasing.

Method aligns well with theoretical predictions.

Abstract

We present the experimental reconstruction of the Wigner function of an individual electronic spin qubit associated with a nitrogen-vacancy (NV) center in diamond at room temperature. This spherical Wigner function contains the same information as the density matrix for arbitrary spin systems. As an example, we exactly characterize the quantum state of a single qubit undergoing a nearly pure dephasing process by Wigner function. The fidelities and purities during this process are extracted from the experimental reconstructed Wigner functions, whose dynamics agree with the theoretical prediction. Our method can be applied to multi-qubit systems for measuring the Wigner function of their collective spin state.