Qiskit Bosons

qiskit-bosons extends the Qiskit SDK with tools for working on bosonic systems. Within its scope it provides the following:

• An efficient data structure for the representation and manipulation of bosonic operators
• A framework for implementing boson-to-qubit encodings, built around shared level encodings (unary with or without projectors, standard binary, Gray), and a library of common mappers
• A framework and library of gates for expressing bosonic circuits
• A transpilation pipeline integrated with the Qiskit transpiler process to synthesize bosonic circuits into qubit-based circuits

Documentation

Documentation for this package will be available on IBM Quantum Platform.

Until then, you can browse the docs of the development branch on GitHub Pages. Previews of the development branch and of labeled pull requests are published there by CI; see docs/README.md.

Installation

Install this package via pip, when possible:

pip install --pre 'qiskit-bosons'

For more installation information, refer to these installation instructions.

Get started

This package covers the whole path from a bosonic operator to a qubit circuit. You can work in the bosonic regime with both, operator and circuit representation, before you choose a truncation and a boson-to-qubit encoding that plug into the multi-representation transpiler pipeline of Qiskit.

All of these features are explained in several guides to help you get started. For an end-to-end overview, start with the Bose-Hubbard guide.

Technical discussion

Design intentions

This package is deliberately designed to align with Qiskit: it builds on a core implemented in Rust and provides first-party language bindings to Python. Its API intends to draw parallels to Qiskit in order to seamlessly integrate into the workflows of users with experience in programming Qiskit. While there exists no C API right now, the architecture is set up to support one if the need for one ever arises in the future. The architecture of this package is also deliberately analogous to that of qiskit-fermions.

A core principle to the design of qiskit-bosons was the decoupling of its bosonic circuit representation from its qubitized form. To be more precise: the bosonic circuits are meaningful by themselves and do not require a mapping to qubit space to be interpretable. Furthermore, the bosonic circuit representation cannot make any assumptions about the truncation and boson-to-qubit encoding applied later on. Both enter only at transpile time.

Contributing

The source code is available on GitHub.

The developer guide is located at CONTRIBUTING.md in the root of this project's repository. By participating, you are expected to uphold Qiskit's code of conduct.

We use GitHub issues for tracking requests and bugs.

Citing this package

If you use this package in your research, use the CITATION.bib file in this project’s repository to cite the appropriate reference(s).

License

Apache License 2.0

Deprecation policy

This package follows semantic versioning and is guided by the principles in Qiskit's deprecation policy. Breaking changes are made only occasionally, to improve the user experience. When possible, old interfaces are kept and marked as deprecated for as long as they can co-exist with the new ones. Each substantial improvement, breaking change, or deprecation is documented in the release notes.