Piquasso is an open-source Python library for simulating photonic quantum computers.

This is a research project, bugs can be expected. If you encounter any, please report it in the Issues page.

Basic example

import numpy as np
import piquasso as pq

with pq.Program() as program:
    pq.Q(0) | pq.Displacement(
        r=np.sqrt(2), phi=np.pi / 4
    )  # Displace the state on mode 0.
    pq.Q(0, 1) | pq.Beamsplitter(
        theta=0, phi=np.pi / 2
    )  # Use a beamsplitter gate on modes 0, 1.

    pq.Q(0) | pq.ParticleNumberMeasurement()  # Measurement on mode 0.

simulator = pq.GaussianSimulator(
    d=3, config=pq.Config(hbar=2)
)  # Prepare a Gaussian vacuum state

result = simulator.execute(program, shots=10)  # Apply the program with 10 shots.

print("Resulting state:", result.state)
print("Detected samples:", result.samples)

This code outputs:

Resulting state: <piquasso._simulators.gaussian.state.GaussianState object at 0x7f3ef3604ac0>
Detected samples: [(0,), (2,), (1,), (2,), (2,), (4,), (1,), (1,), (4,), (1,)]

For more details, please refer to the Piquasso documentation.

Install

Piquasso and its dependencies can be installed via pip:

pip install piquasso

If you have problems installing Piquasso as above, try installing from source with

pip install --no-binary=:all: piquasso

When installing from source does not work on your machine, please open an issue in the Issues page.

If you wish to, you can also install piquassoboost for performance improvement.

If you are doing research using Piquasso, please cite us as follows:

@article{Kolarovszki_2025,
   title={Piquasso: A Photonic Quantum Computer Simulation Software Platform},
   volume={9},
   ISSN={2521-327X},
   url={http://dx.doi.org/10.22331/q-2025-04-15-1708},
   DOI={10.22331/q-2025-04-15-1708},
   journal={Quantum},
   publisher={Verein zur Forderung des Open Access Publizierens in den Quantenwissenschaften},
   author={
      Kolarovszki, Zoltán
      and Rybotycki, Tomasz
      and Rakyta, Péter
      and Kaposi, Ágoston
      and Poór, Boldizsár
      and Jóczik, Szabolcs
      and Nagy, Dániel T. R.
      and Varga, Henrik
      and El-Safty, Kareem H.
      and Morse, Gregory
      and Oszmaniec, Michał
      and Kozsik, Tamás
      and Zimborás, Zoltán
   },
   year={2025},
   month=apr,
   pages={1708}
}

Documentation

The documentation is available at https://piquasso.readthedocs.io/.

How to contribute?

We welcome people who want to make contributions to Piquasso, be it big or small! If you are considering larger contributions to the source code, please contact us first.

We welcome bug reports, suggestions, and any feedback about Piquasso. To share these, open an issue or fill out the Piquasso User Survey.

Development guide

To install development dependencies, use:

pip install -e ".[dev]"

For document generation one should use

pip install -e ".[docs]"

Additionally, pandoc needs to be installed. To building the documentation, execute make html in the docs folder. After a successful build, the documentation is available under docs/_build.

For running files under benchmarks/ or scripts/, please issue

pip install -e ".[benchmark]"

For building Piquasso, one also needs to install build dependencies:

pip install 'pybind11[global]' scikit-build-core cmake

Linux

To build Piquasso for local development on Linux, run

cmake -B build -DCMAKE_INSTALL_PREFIX=$(pwd)
cmake --build build
cmake --install build

Here, the -DCMAKE_INSTALL_PREFIX=$(pwd) flag is needed to copy shared libraries into the source tree for development.

Windows

1. Open a terminal (e.g., Command Prompt or PowerShell).
2. Navigate (cd) to the root directory of the Piquasso project.
3. Run the following command:

build.bat

The build.bat script automatically runs all the required commands for building the project.

Alternatively, you can run the commands manually for building the project:

cmake -B build -DCMAKE_INSTALL_PREFIX="%cd%" -DPYBIND11_FINDPYTHON=ON
cmake --build build --config Debug
cmake --install build --config Debug

Testing

All tests and additional checks can be run using tox. After installation, run the following command:

tox -e py312

Alternatively, you can run only the tests using pytest. After installation, run the following command:

pytest tests

Besides testing, we have several additional checks:

1. We use an automatic formatting tool called black. To run automatic formatting, simply execute

   black .
   

2. Moreover, we also use a linter called flake8, which can be executed by issuing

   flake8
   

3. Finally, we use a static type checker called mypy on the piquasso folder:

   mypy piquasso