v0.9.0

[0.9.0] - 2025-01-30

This new version comes with some new big features and changes.

PyZX now supports a Multigraph backend that allows graphs to have multiple edges. Meaning that parallel edges between spiders don't have to be automatically simplified to a single edge. This makes it easier to work with ZH- and ZW-diagrams, and makes it easier to implement other extensions like qudits in the future. As all rewrites have to be reworked to work with multigraphs it is very likely that there are still some semantics breaking things going on. If you use multigraphs be sure to regularly check whether semantics are preserved.

The other big change is that certain features are now deprecated. All Quantomatic features have been removed, since Quantomatic has not seen any major developments in the last 5 years. The file format for saving Graphs to json was based on the Quantomatic format and hence was quite complicated. A new simplified future proof format that also supports the new multigraphs is now implemented and replaces the old format. Graphs in the old format can still be loaded in for backwards compatibility. The diagram editor built into PyZX has also been deprecated as ZXLive can now do pretty much everything better. It is still usable, but requires an older version of ipywidgets which was causing issues with compatibility with other libraries.

There are also some new experimental functions and features: calculating an extended gflow and Pauli flow for ZX-diagrams, calculating and visualising a Pauli web, and drawing diagrams in three dimensions.

Added

• Multigraph graph backend that allows parallel edges between nodes. Many simplification routines work with the Multigraph backend, but some might still have some unexpected behaviour. Tread carefully. Many of the features and upgrades were implemented by @akissinger and @RazinShaikh.
• Can now compute focussed gflows, and extended gflows that can deal with Pauli vertices (see functions in gflow.py). Courtesy of @akissinger.
• Compute and draw Pauli webs for ZX-diagrams with Pauli flow. See demos/PauliWebs.ipynb and pauliweb.py. Courtesy of @akissinger.
• D3 drawing now supports drawing in 3D. Use function drawing.draw_3d for this. Courtesy of @akissinger.
• Some new useful rewrites for H-boxes in hsimplify: A replace_hadamard that replaces an H-box with a H-edge, and had_edge_to_hbox that does the opposite. Courtesy of @jvdwetering.
• A new function cut_vertex in simulate to decompose a single graph into two graphs with the vertex cut away. link. Courtesy of @mjsutcliffe99.
• generate.qft for generating a quantum Fourier transform circuit. Courtesy of @akissinger.
• QASM parser now understands multi-character register names. link. Courtesy of @contra-bit.
• Circuit.verify_equality function now takes optional parameter up_to_global_phase. Courtesy of @akissinger.

Changed

• PyZX now uses a new simplified future-proof format for storing Graph instances, that also supports the new Multigraph backend. The old format based on the Quantomatic format still works, but is no longer the default.
• All functionality related to Quantomatic has been removed.
• The built-in editor for diagrams is now deprecated, and the version requirements for ipywidgets necessary for it to work have been removed.

Fixed

• Bug in to_graph_like link.
• Some more reasonable checks and error messages when calling full_reduce wrongly link. Courtesy of @dlyongemallo.
• Scalar now correctly updates when creating .adjoint() of a Graph link. Courtesy of @rafaelha.
• Several fixes for the Poly class for better support of symbolic angles. Courtesy of @lia-approves and @RazinShaikh.
• Can now generate single-qubit Clifford+T circuits using generate.cliffordTmeas link. Courtesy of @amirebrahimi.
• Fixed bug in simplify.to_clifford_normal_form_graph link. Courtesy of @rafaelha.
• Bug in the cat decomposition in simulate.py. link. Courtesy of @alexkoziell.