CHANGELOG.md

Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog. Right now this project is in Beta and does not yet follow Semantic Versioning. Hence, occasionally changes will be backwards incompatible (although they will all be documented here).

[0.8.0] - 2024-02-14

This release includes breaking changes!

Major new features are support for W-spiders and Z-boxes, which are generators used in certain extensions of the ZX-calculus, such as in this paper which served as the motivation. It also adds more formal support for symbolic phases through the addition of a Poly class that can represented polynomial expressions containing Boolean and continuous variables.

These features were implemented to support the development of ZXLive, a new graphical proof assistant for ZX-diagrams.

This release includes some changes that are not backwards compatible. The most important of which is changing how inputs and outputs are stored in the json format. This means that json files produced by Graph.to_json() are not parsible by older versions, and older versions are no longer parsible by this newer version. In addition, the gate CX has been renamed to XCX to make it more clear that it is in fact not an alternative name for the CNOT gate. Finally, the FSim gate now takes as first arguments the control and target, and only then the angles, in order to be consistent with the other gate definitions.

Added

• Support for W nodes and Z boxes (courtesy of @RazinShaikh).
• Support for symbolic phases that can either be Boolean or continuous variables. This is implemented through the new Poly class (standing for Polynomial) (courtesy of @RazinShaikh).
• Support for Jupyter notebooks in documentation using nbsphinx (courtesy of @dlyongemallo).
• Jupyter notebook documenting all supported gates (courtesy of @dlyongemallo).
• Support for OpenQASM 3.0 (courtesy of @dlyongemallo).
• A function is_well_formed to check that a graph is a well-formed ZX-diagram (courtesy of @RazinShaikh).
• A function is_pauli to check whether a phase is Pauli (courtesy of @y-richie-y).
• A function GraphDiff that calculates what actions are needed to bring one graph to another (used in ZXLive).
• Functions simplify.to_clifford_normal_form_graph and extract.extract_clifford_normal_form.
• Lazy import of some dependencies to improve start-up time.

Changed

• Class CX, which refers to an X-controlled X gate, renamed to XCX for clarity.
• Parameters for FSim changed to put control and target before angles, for consistency with other gates.
• json format correctly remembers input/output ordering (older json no longer parsible).

Fixed

• A bunch of mypy issues.
• json export and import supports Poly phases.
• Grounds being dropped during composition and other operations (#177 courtesy of @ABorgna).
• The tensorfy function used the visual ordering of inputs and outputs, instead of the correct ordering (#168).
• Several qasmparser bugs (courtesy of @dlyongemallo).
• Incorrect gate name when optimization combines phases into single gate (#134 courtesy of @bichselb).
• The gflow function returned a gflow when it shouldn't (#114 courtesy of @mafaldaramoa).
• Error in qasmparser when importing a gate with a negative phase (#112).

[0.7.3] - 2023-02-22

Hotfix for bug Graph.compose() function

Fixed

• BaseGraph.compose() now functions as expected.

[0.7.1] - 2023-02-02

This release improves support and documentation for routing circuits (courtesy of @aborgna-q). In particular it implements the architecture-aware synthesis technique for phase polynomials of this paper.

The way that the D3 library is loaded is also changed, meaning that the D3 visualization should now work on more systems, in particular on Google Colab. This should also hopefully fix some errors with loading the diagram editor (although this still relies on Jupyter's widget library so that that will only work locally).

Added

• New routing method for phase polynomial circuits zx.routing.route_phase_poly adapted from this paper (courtesy of @Aerylia and @aborgna-q).
• Support for more architectures in routing library (@Aerylia and @aborgna-q).
• Support for more gates of PyQuil (@Aerylia and @aborgna-q).
• New phase polynomial circuit generation functions zx.generate.phase_poly, zx.generate.phase_poly_approximate and zx.generate.phase_poly_from_gadgets
• New scripts cnots and phasepoly that generates random CNOT and phase polynomial circuits (@aborgna-q).
• Basic support for symbolic angles using sympy when doing rewriting (courtesy of @y-richie-y).
• Support for Quipper files that do not contain the "nocontrol" keyword.
• Added support for ry gates in QASM files (courtesy of @mgrzesiuk).

Changed

• Requirement of ipywidgets has been updated from ipywidgets>= 7.5 to ipywidgets>=7.5,<8 as newer version broke the diagram editor.
• Script mapper has been renamed to router.

Fixed

• Fixed bug in Circuit.verify_equality where it would sometimes say that circuits are equal while they are not (courtesy of Julian Verweij).

[0.7.0] - 2022-02-19

This release adds several new features: support for evaluating ZX-diagrams as tensor networks using the hypergraph contraction methods of quimb, basic support for interacting with the Rust port of PyZX quizx, support for 'hybrid' ZX-diagrams that contain classical wires and measurements, as well as several heuristics for trying to optimise the CNOT count of a circuit that is to be extracted from a ZX-diagram.

There is one small breaking change, which is that Graph.inputs and Graph.outputs are now methods that return a list, instead of being lists themselves.

Added

• Added support for evaluating ZX-diagrams as tensor networks in quimb (courtesy of Paul Tirlisan).
• Added quizx backend for the Graph class.
• Graph vertices can now carry a ground generator. This makes it possible to represent measurements and classical control in the diagrams. See the accompanying paper (courtesy of ABorgna).
• Added extract.lookahead_extract that uses heuristics to extract circuit with less CNOT gates (courtesy of VladMoldoveanu).
• Added local_search submodule for doing simulated annealing on rewrites of a ZX-diagram to try to get it to be extracted with less CNOTS (courtesy of Ryan Krueger).
• Added new rewrite rule for ZH-diagrams hsimplify.par_hbox_intro_simp() that can remove some H-boxes.
• Added several new rewrite rules to basicrules and mbqc.
• QASM parser: added support for controlled-Hadamard and controlled-Z phase gates.
• QC parser: added support for SWAP gates (courtesy of wdomitrz).
• Added Graph.set_inputs() and Graph.set_outputs() to set a list of vertices to be the inputs/outputs of a diagram.
• Added Graph.num_inputs() and Graph.num_outputs() to get the number of inputs and outputs of a diagram.

Changed

• Graph.inputs is now a method that returns a list of inputs, instead of Graph.inputs being a list itself. The same for Graph.outputs.

Fixed

• Several incorrect scalars were fixed in ZH-diagram rewrite rules.

[0.6.4] - 2021-01-27

The main feature added is support for copying and pasting inside the editor. This release should also hopefully fix the issue where users of the PyPI version can't use zx.draw and the editor.

Added

• Added functionality to copy and paste parts of a diagram in the editor.
• qasm files can now include u1/u2/u3 gates.
• Method BaseGraph.merge() to merge two graphs in place.
• Method BaseGraph.subgraph_from_vertices() to get the induced subgraph from a set of vertices.

Changed

• tikz_to_graph() is now a bit more versatile in what it accepts as valid phases.
• matrix_to_latex() is slightly more intelligent about parsing numbers.
• Changed colours in editor to match those of zx.draw.

Fixed

• Decomposing a Hadamard into Euler angles gave wrong scalar.
• Added d3.v5.min.js to the manifest, which hopefully prevents the issue where people using the PyPI version can't see graphs drawn with d3.

[0.6.3] - 2020-12-2

Added

• Added settings.drawing_auto_hbox to toggle the default value of auto_hbox when using zx.draw().
• Added function generate.spider to construct a graph containing a single spider.
• Added function Graph.translate(x,y) to translate all the coordinates in the Graph instance by the specified amount.
• Added additional rewrite rule to editor for H-box fusion.
• Added hsimplify.zh_simp() rewrite strategy that does a collection of rewrites of increasing difficulty to simply ZH-diagrams.

Changed

• The par_hbox() simplification can now also handle wires with NOTs on them.
• The copy rule in the editor now also understands how to copy a |-> state through an H-box.

Fixed

• Fixed exception in editor that made it unusable.
• Fixed bug when matching parallel Hadamards with match_hadamards().
• Undo in editor correctly remembers scalar.

[0.6.2] - 2020-11-16

Added

• Added extract_simple function as simple method for extracting circuits from ZX-diagrams that have causal flow.
• Added function find_scalar_correction(g1,g2) that gives the correct scalar to make g1 and g2 equal (assuming they represent the same linear map up to a global scalar).
• Added function drawing.graphs_to_gif that takes in a list of Graphs and outputs an animated gif showing them in sequence. Note that this requires imagio to be installed.
• The output classes for each of the vertex and edge types in the methods for converting a Graph to tikz format can now be set using zx.settings.tikz_classes.
• draw_matplotlib, draw_d3 (and hence zx.draw) and editor.edit have additional optional argument show_scalar to display the scalar of the Graph.
• Added argument draw_scalar to all functions converting a Graph into tikz format to toggle the display of the scalar of the Graph in the tikz output.
• The Graph method to_json now remembers the scalar of the graph by default (and Graph.from_json can handle this).

Fixed

• basicrules.strong_comp now preserves scalar correctly.
• Undo in editor now remembers scalar correctly.
• bialg and copy rewrites in editor now preserve scalar correctly.

[0.6.1] - 2020-10-30

Added

• Mac users can now Command-click instead of Ctrl-click in the editor.
• Added Graph.to_tikz and Graph.from_tikz functions in order to convert ZX-diagrams to and from a tikz file.
• Can now compose Graph instances using the * operator.
• Added function Graph.add_edge_smart as a convenience wrapper for Graph.add_edge_table.
• Added Graph.auto_detect_io as an alias of Graph.auto_detect_inputs, perhaps deprecating the old function at some point.
• Added top-level scalar magic constants ONE, SQRT_TWO, TWO, SQRT_TWO_INV, TWO_INV in order to more easily set the value of g.scalar for Graph instances.

Changed

• Changed default behaviour of preserve_scalar argument in compare_tensors: now always defaults to False.
• Circuit.verify_equality now doesn't say SWAP is equal to the identity. Added an argument to get back the original behaviour.
• Changed the output of zx.draw slightly: more visible labels, more colourblind friendly colours.

Fixed

• Fixed several bugs in the rewriting with functions in editor_actions.py
• Fixed bug where Graph.num_edges() wouldn't return correct number of edges.
• Fixed error that occurred when running pyzx from a different drive than the install drive on Windows.
• Fixed several bugs in hsimplify.hpivot_simp.
• Fixed exception when entering negative phase in editor.

[0.6.0] - 2020-06-16

This release has made many backwards incompatible changes to the API in order to remove some old functions and rename other functions to more logical or consistent names. In particular, all British spelling names have been renamed to American spelling names. After this release the API should be significantly more stable.

The license for this project has been changed from GPLv3 to Apache2, in order to streamline the process of using PyZX with other open-source quantum computing projects.

Added

• All functions now have typing hints, and mypy runs successfully on PyZX.
• ZX-diagram editor that runs in a Jupyter notebook. See the documentation for the details.
• New function zx.matrix_to_latex to pretty-print a numpy matrix (useful in Jupyter notebook in combination with ipywidgets.Label).
• There is now a zx.settings object that stores some global values that affect how PyZX draws stuff, and how it interacts with external executables.
• Added zx.draw_d3 and zx.draw_matplotlib to account for new behaviour of zx.draw.

Changed

• Circuit extraction algorithm has been updated to use the one from the There and back again paper.
• Main circuit extraction function has been renamed from zx.extract.streaming_extract tozx.extract_circuit.
• zx.draw now intelligently changes whether to use d3 or matplotlib. Setting can be changed using zx.settings.drawing_backend.
• The official language of PyZX is now American English, instead of a mix of British and American english.
• g.normalise() has been renamed to g.normalize().
• g.neighbours() has been renamed to g.neighbors().
• The various functions for converting ZX-diagrams into json or other formats now have become methods of the Graph instance themselves. I.e. g.to_json() instead of zx.io.graph_to_json(g) and Graph.from_json(js) instead of zx.io.json_to_graph(js).
• g.auto_detect_inputs() is now smarter, and turns any boundary node that 'points right' into an input, and similarly for outputs.
• zx.compare_tensors now automatically only checks equality up to scalar if one of the arguments is a Circuit.
• add_edge_table function in BaseGraph now supports more operations involving H-boxes, so that ZH-calculus simplifications can apply to more diagrams.
• Numerous small bugfixes that were found as a result of mypy type-checking that probably weren't affecting any existing code.

Removed

• Several files and functions that weren't being used and only caused confusion to new users, including phasepoly.py, and all the *_threaded functions from simplify.py
• Removed support for running PyZX inside of Quantomatic, as this functionality probably didn't work anyway (since PyZX now used Python3 functionality).

Deprecated

• zx.d3.draw is deprecated. Use zx.draw or zx.draw_d3 instead.
• zx.extract.streaming_extract is deprecated. Use zx.extract_circuit instead.

[0.5.1] - 2020-04-08

Hotfix release to fix syntax error that prevented scripts from being called.

[0.5.0] - 2020-04-07

First PyPI release.