QuaCCAToo: Quantum Color Centers Analysis Toolbox

QuaCCAToo is a Python library for simulating and analyzing spin dynamics of color centers for quantum technology applications. The library provides several predefined pulsed sequences, analysis methods and quantum systems divided into four integrated modules: qsys, pulsed_sim, analysis and exp_data. The systems’ time evolution under pulsed experiments are calculated through quantum master equations based on the provided Hamiltonian, with realistic pulses in the laboratory frame without rotating frame approximations. The software is built on top of QuTip, inheriting its object-oriented framework and the Qobj class. The code is continously improved and maintained using pytest, ruff, pylint and ty.

If you used QuaCCAToo in your work, please cite Digital Twin Simulations Toolbox of the Nitrogen-Vacancy Center in Diamond.

The documentation for QuaCCAToo is available here. Merge requests welcome at the Github repository!

To see usage examples, check the tutorial notebooks linked here. They contain:

• 01 - Rabi and Hahn of a Spin Half System: simplest two-level system, where we first define the system and plot the energy levels. Following that, a Rabi oscillation is simulated for two different pulse vectors, with the results being fitted and plotted in the Bloch sphere. Lastly, we simulated a Hahn echo decay for a modeled collapse operator.

• 02 - Ramsey and PODMR with NV: simulation of nitrogen vacancy centers in diamond, first calculating the energy levels, then performing Rabi and comparing with experimental data. Ramsey and PODMR are also simulated.

• 03 - Conditional Gates with NV-13C: conditional gates with resonant MW and RF pulses of an NV center strongly coupled to a 13C nuclear spin from Observation of Coherent Oscillation of a Single Nuclear Spin and Realization of a Two-Qubit Conditional Quantum Gate.

• 04 - Sensing and Control of 13C Spin with NV: dynamical decoupling sequences for sensing and controling coupled 13C nuclear spins from Coherent dynamics of coupled electron and nuclear spin qubits in diamond and Detection and control of individual nuclear spins using a weakly coupled electron spin.

• 05 - Ambiguous Resonances in DD with NV: simulation of Ambiguous Resonances in Multipulse Quantum Sensing with Nitrogen Vacancy Centers.

• 06 - Teleportation Protocol with NV Pair: simulation of NV teleportation protocol in Unconditional quantum teleportation between distant solid-state quantum bits.

• 07 - Double Electron-Electron Resonance with P1 Centers in Diamond: simulation of P1 sensing with NVs diamond from Local nanoscale probing of electron spins using NV centers in diamond.

• 08 - Quantum Gates via Dynamical Decoupling with NV: simulation of Quantum Gates via Dynamical Decoupling of Central Qubit 15NV Center in Diamond.

Class Hierarchy

QuaCCAToo is an object-oriented package organized with the following classes:

• QSys defines the quantum system of the problem. It has an obligatory intrinsic internal Hamiltonian \(H_0\), optional initial state, observable and a set of collapse operators. On QSys, calculates the eigenstates and eigenvalues of the system and has methods for truncating the systems and adding other spins. QuaCCAToo provides NV (NV_Sys) as a predefined system for nitrogen vacancy centers in diamonds, more systems will be provided soon.

• PulsedSim contains the logic for performing the simulation of pulsed experiments upon a QSys object. It has attributes of a pulse sequence containing a set of pulses and free evolutions, control Hamiltonian \(H_1\), experiment variable and simulation results. Many predefined common pulse sequences are given in predef_seqs and predef_dd_seqs modules. Different pulse shapes are predefined in the pulse_shapes module.

• ExpData is a class to load experimental data and perform basic data processing, such as rescaling, subtracting columns or performing polynomial baseline corrections.

• Analysis can be used either on simulation or experimental results, with a series of methods like for fitting (based on lmfit), Fourier transforms and data comparison. The class can also used for plotting the results in multiple forms, including density matrix histograms and Bloch spheres. Several fit models and functions relevant for analysis of color centers are provided in the fit_functions module.

Contents:

• Installation
  • Normal installation
  • Development installation
• Tutorials
  • 01 - Rabi and Hahn of a Spin Half System
  • 02 - Ramsey and PODMR with NV
  • 03 - Conditional Gates with NV-13C
  • 04 - Sensing and Control of 13C Spin with NV
  • 05 - Ambiguous Resonances in DD with NV
  • 06 - Teleportation Protocol with NV Pair
  • 07 - Double Electron-Electron Resonace with P1 Center
  • 08 - Quantum Gates via Dynamical Decoupling with NV
• QuaCCAToo modules
  • qsys
  • NV_Sys
  • pulsed_sim
  • predef_seqs
  • predef_dd_seqs
  • pulse_shapes
  • analysis
  • fit_functions
  • exp_data
  • utils

Featured In

• 12. Tsunaki, A. Singh, S. Trofimov, & B. Naydenov. (2025). Digital Twin Simulations Toolbox of the Nitrogen-Vacancy Center in Diamond. Advanced Quantum Technologies, e00691. doi: 10.1002/qute.202500691.

• 12. Tsunaki, A. Singh, K. Volkova, S. Trofimov, T. Pregnolato, T. Schröder, & B. Naydenov. (2025). Ambiguous resonances in multipulse quantum sensing with nitrogen-vacancy centers. Physical Review A, 111(2), 022606. doi: 10.1103/PhysRevA.111.022606.

• 12. Tsunaki, M. Dotan, K. Volkova, & B. Naydenov. (2025). Quantum Gates via Dynamical Decoupling of Central Qubit on IBMQ and 15NV Center in Diamond. doi: arXiv:2509.22107 quant-ph.

• 19. Trofimov, C. Thessalonikios, V. Deinhart, A. Spyrantis, L. Tsunaki, K. Volkova, K. Höflich, & B. Naydenov. (2025). Local nanoscale probing of electron spins using NV centers in diamond. 10.1016/j.diamond.2026.113530.

If you used QuaCCAToo in your work, please let us know so we can add it to the list!