QuLTRA is an open-source Python library for the analysis of superconducting circuits that include both lumped elements (capacitors, inductors, Josephson junctions, resistors) and distributed components (such as coplanar waveguides and CPW couplers).
The library provides tools to compute:
-Eigenfrequencies of the circuit modes,
-Dissipation rates, including coupling to external lines,
-The cross-Kerr matrix, describing the nonlinear interactions between modes.
QuLTRA is designed to support fast, layout-independent modeling in the early design stages, before full electromagnetic simulations.
QuLTRA Python package, release v1.0.1, archived on Zenodo: DOI 10.5281/zenodo.16897531. The preprint of the article is on arXiv:https://arxiv.org/abs/2509.03651
You can install QuLTRA directly from PyPI using pip:
pip install qultraFor more details, visit the PyPI project page: https://pypi.org/project/qultra/
You can also install QuLTRA by directly cloning the repository
git clone https://github.com/SimonaZaccaria/QuLTRA.git
cd QuLTRA
pip install -e .For the complete documentation, please visit the QuLTRA web page.
Future improvements of QuLTRA may involve the implementation of a graphical interface, the possibility to export the full Hamiltonian of quantum circuits as a Qobj() for seamless integration with QuTiP, the calculation of zero-point fluctuation elements via energy participation coefficients that account for higher-order terms in the Taylor expansion, and the extension of the method to circuits with strong anharmonicity.
For inquiries or to contribute to the project, please contact Simona at simona.zaccaria4@unibo.it.