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For a high-level overview of Qadence features,check out our white paper.

**For more detailed information,check out the documentation.

**For any questions or comments,feel free to start a discussion.**

• Ablock-based system for composingcomplex digital-analogprograms in a flexible and scalable manner, inspired by the Julia quantum SDKYao.jl and functional programming concepts.

• An intuitiveexpression-based system developed on top of the symbolic librarySympy to constructparametric quantum programs easily.

• Out-of-the-boxautomatic differentiability of quantum programs withPyTorch integration.

• High-order generalized parameter shift rules fordifferentiating parametrized quantum operations.

• Asimple interface to work withinteracting neutral-atom qubit systemsusingarbitrary registers topologies.

Qadence is available onPyPI and can be installed usingpip as follows:

pip install qadence

The default, pre-installed backend for Qadence isPyQTorch, a differentiable state vector simulator for digital-analog simulation based onPyTorch. It is possible to install additional,PyTorch -based backends and the circuit visualization library using the following extras:

• visualization: A visualization library to display quantum circuit diagrams.
• protocols: A collection ofprotocols for error mitigation in Qadence.
• libs: A collection offunctionalities for graph machine learning problems build on top of Qadence.
• pulser: ThePulser backend for composing, simulating and executing pulse sequences for neutral-atom quantum devices (experimental).

Qadence also supports aJAX engine which is currently supporting theHorqrux backend.horqrux is currently only available via thelow-level API.

To install individual extras, use the following syntax (IMPORTANT Make sure to use quotes):

pip install"qadence[pulser,visualization]"

To install all available extras, simply do:

pip install"qadence[all]"

IMPORTANTBefore installingqadence with thevisualization extra, make sure to install thegraphviz packageon your system:

# For Debian-based distributions (e.g. Debian, Ubuntu)sudo apt install graphviz# on MacOSbrew install graphviz# via condaconda install python-graphviz

On Windows Linux Subsystem (WSL2) it has been reported that in some cases "wslutilities" must be installed.Please follow instructionshere for your flavour.For example on Ubuntu 22.04 LTS and later you must run:

sudo add-apt-repository ppa:wslutilities/wslusudo apt updatesudo apt install wslu

Before making a contribution, please review ourcode of conduct.

• Submitting Issues: To submit bug reports or feature requests, please use ourissue tracker.
• Developing in qadence: To learn more about how to develop withinqadence, please refer tocontributing guidelines.

We recommend to use thehatch environment manager to installqadence from source:

python -m pip install hatch# get into a shell with all the dependenciespython -m hatch shell# run a command within the virtual environment with all the dependenciespython -m hatch run python my_script.py

WARNINGhatch will not combine nicely with other environment managers such as Conda. If you still want to use Conda,install it from source usingpip:

# within the Conda environmentpython -m pip install -e.

Users also report problems running Hatch on Windows, we suggest using WSL2.

If you use Qadence for a publication, we kindly ask you to cite our work using the following BibTex entry:

@article{qadence2025,author = {Seitz, Dominik and Heim, Niklas and Moutinho, João and Guichard, Roland and Abramavicius, Vytautas and Wennersteen, Aleksander and Both, Gert-Jan and Quelle, Anton and Groot, Caroline and Velikova, Gergana and Elfving, Vincent and Dagrada, Mario},year = {2025},month = {01},pages = {1-14},title = {Qadence: a differentiable interface for digital and analog programs},volume = {PP},journal = {IEEE Software},doi = {10.1109/MS.2025.3536607}}

Qadence is a free and open source software package, released under the Apache License, Version 2.0.