DOI: 10.5061/dryad.547d7wmj0
title: Data from: Certifying the quantumness of a nuclear spin qudit through its uniform precession

description: Spin precession is a textbook example of the dynamics of a quantum system
 that exactly mimics its classical counterpart. Here we challenge this view
 by certifying the quantumness of exotic states of a nuclear spin through
 its uniform precession. The key to this result is measuring the
 positivity, instead of the expectation value, of the x-projection of the
 precessing spin, and using a spin &gt; 1/2 qudit, that is not
 restricted to semi-classical spin coherent states. The experiment is
 performed on a single spin-7/2 123Sb nucleus, implanted in a silicon
 nanoelectronic device, amenable to high-fidelity preparation, control, and
 projective single-shot readout. Using Schrödinger cat states and other
 bespoke states of the nucleus, we violate the classical bound by 19
 standard deviation, proving that no classical probability distribution can
 explain the statistic of this spin precession, and highlighting our
 ability to prepare quantum resource states with high fidelity in a single
 atomic-scale qudit.
description: # Data from: Certifying the quantumness of a nuclear spin qudit through
 its uniform precession
 [https://doi.org/10.5061/dryad.547d7wmj0](https://doi.org/10.5061/dryad.547d7wmj0) ## Description of the data and file structure Data Repository for "Certifying the Quantumness of a Nuclear Spin Qudit through its Uniform Precession" This repository contains the data and Jupyter source files to generate figures supporting the research paper "Certifying the Quantumness of a Nuclear Spin Qudit through its Uniform Precession", which can be found here: [https://arxiv.org/abs/2410.07641](https://arxiv.org/abs/2410.07641). The data was collected using the qCoDeS python package and is stored in qCoDeS datasets. ### Files and variables #### File: detecting\_quantumness.zip **Description:**  The detecting_quantumness.zip repository is organized into the following directories: **analysis/**: Contains scripts and notebooks for analyzing the experimental and simulation data presented in the paper. Specifically: * GR&Cat paper msmt.ipynb is the raw, unedited Juypter notebook used for performing all the measurements. The relevant sections are 'scarani_protocol', 'husimi/wigner_reconstruction', and * state_tomo.py contains analysis code of the quantum state tomography. It takes numpy arrays from 'state_probs_scarani/' which are the measurement results from the quantum state tomography. * DensityMatrixReconstruction.ipynb is the notebook containing the quantum state tomography analysis and produces the files named: 'results_x_x_xpts.pkl', which are plotted in the 'paper_figures/' directory. **animations/**: Includes visualizations and animations used to illustrate the dynamic behavior of the nuclear spin qudit in various quantum states. * The ladder climbing protocol is illustrated in ladder.gif * The ladder.gif is produced in the Ladder_climbing.ipynb notebook * Same for precession.gif and Uniform_precession.ipynb **data/**: Stores all the experimental datasets used in this study. The data can be loaded using the qCoDeS library. A legacy version of qCoDeS (v0.16) was used for the experiments. * The datasets are compatible with the qcodes_loop package in case a newer version of qCoDeS is used for loading. * See Code/software below for instructions how to load data with a newer qCoDeS package. * The datasets are stored in folders named after the date of the measurement, i.e., '2023-10-23/' * The raw data is extracted in the 'paper figures/' directory. **paper figures/**: Contains the Jupyter sources files to generate figures for the paper, including processed plots, graphs, and any related assets. It extracts the data stored in 'data/' and generates the plots. It also includes the illustrator files needed to reproduce the paper figures. Specifically: ``` - 'fig1-5/' folders contain all the code necessary to reproduce the figures in the main text. - In those folders, the code can be found in the figx.ipynb files - 'supplement/' folders contain all code for the figures in the supplementary of the paper. ``` **simulation/**: Holds the simulation scripts and results used to model the precession of the nuclear spin qudit, providing theoretical context for the experimental findings. * quantumness_protocol.ipynb contains the simulation of the protocol, both for the ideal and reconstructed density matrices * it extracts the initial density matrix from 'simulation/datasets/' dataset_references.txt exactly specifies which dataset is used for which .ipynb file ``` ## Code/software The experimental data stored in the data/ folder was originally collected using a legacy version of the qCoDeS library. To load and analyze the data: ``` If using the legacy qCoDeS version (v0.16): You can directly load the datasets using the qc.load_data() method. If using a newer version of qCoDeS: The qcodes_loop package provides backward compatibility for loading older datasets. You can use the qcodes_loop library to load and process the datasets without issue. ``` Usage To load a dataset in Python: &gt; import qcodes as qc &gt; &gt; \# Example of loading a dataset &gt; &gt; data = qc.load_data(r'path_to_dataset') If using qcodes_loop for legacy dataset loading: &gt; from qcodes_loop.data.data_set import load_data &gt; &gt; \# Load dataset with qcodes_loop &gt; &gt; data = load_data(r'path_to_dataset') ```