QSO User Guide
QSO is a quantum simulator written in pure Rust, with a Python package and a command-line tool. It simulates quantum circuits exactly, as pure states or as density matrices with noise, and runs variational and textbook algorithms on top of them. It also simulates quantum walks on arbitrary graphs and samples photons in linear interferometers. Its signature geometry is Metatron’s Cube, the complete graph K₁₃ on the 13 centres of the Fruit of Life.
The rule of the project is no claim without a test. Every algorithm is compared with an independent reference: a closed form, a published value, a dense-matrix computation, a second method or another simulator. The chapter How QSO is validated describes the checks, and the technical note reports them in full.
What this guide covers
| Chapter | Topics |
|---|---|
| Circuits and states | Gates, simulation, sampling, observables, OpenQASM |
| Parameters and gradients | Symbolic parameters, adjoint and parameter-shift gradients |
| Variational algorithms | VQE, QAOA, variational and graph classifiers |
| Noise | Channels, noise models, density matrices, shot estimates |
| Graphs | Graph library, specifications, symmetry groups |
| Quantum walks | Continuous-time walks, spatial search, dephasing |
| Boson sampling | Permanents, interferometers, exact sampling |
| Command line | The qso tool |
The tutorials are Jupyter notebooks from
docs/tutorials.
They are executed every time this site is built, so their output always comes
from the current code.
Examples use the Python package, with Rust equivalents where the interfaces differ. The two share one implementation. Every code block in this guide is run when the site is built.
Versions
This guide describes the code on the main branch. Released versions are on
PyPI and
crates.io; the
changelog lists what
changed in each release.