Pairinteraction - A Rydberg Interaction Calculator

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The pairinteraction software calculates properties of Rydberg systems. The software consists of a C++/Python library and a graphical user interface for pair potential calculations. For usage examples visit the tutorials section of the documentation. Stay tuned by signing up for the newsletter so whenever there are updates to the software or new publications about pairinteraction we can contact you. If you have a question that is related to problems, bugs, or suggests an improvement, consider raising an issue on GitHub.

Please cite us

Sebastian Weber, Christoph Tresp, Henri Menke, Alban Urvoy, Ofer Firstenberg, Hans Peter Büchler, Sebastian Hofferberth, Tutorial: Calculation of Rydberg interaction potentials, J. Phys. B: At. Mol. Opt. Phys. 50, 133001 (2017), arXiv:1612.08053

  author = {Weber, Sebastian and Tresp, Christoph and Menke, Henri and Urvoy, Alban and Firstenberg, Ofer and B{\"u}chler, Hans Peter and Hofferberth, Sebastian},
  title = {{Tutorial: Calculation of Rydberg interaction potentials}},
  journal = {J. Phys. B: At. Mol. Opt. Phys.},
  volume = {50},
  number = {13},
  pages = {133001},
  year = {2017},
  doi = {10.1088/1361-6455/aa743a},
  url = {}

See works citing pairinteraction on Google Scholar and the ADS Digital Library.


Binary builds are available for GNU/Linux, Mac OS X, and Windows through GitHub Releases. For more information, read the installation docs.

Main Features

The pairinteraction software simulates systems of one or two Rydberg atoms. It supports a lot of neat features, the major of which are listed below:

  • Stark and Zeeman maps for single atom states
  • Pair potentials taking into account electromagnetic fields in arbitrary directions
  • Multipole interaction up to arbitrary order
  • Numerical and analytical methods for radial matrix elements
  • Automatic exploitation of symmetries
  • Calculation of \(C_6\) coefficients in degenerate subspaces
  • High performance C++ backend, Python interface with NumPy support
  • MATLAB compatible data export


Main window with sample configuration on Windows 10 64-bit.
Main window with sample configuration on Mac OS X El Capitan.
Stark map for a single Rydberg atom.
Quadratic Zeeman effect for a single Rydberg atom.


The pairinteraction software was originally developed at the 5th Institute of Physics and the Institute for Theoretical Physics III of the University of Stuttgart, Germany. Currently it is maintained by developers at the Institute for Theoretical Physics III of the University of Stuttgart in Germany, the Department of Physics of the University of Otago in New Zealand, and the Department of Physics, Chemistry and Pharmacy of the University of Southern Denmark in Denmark.