Importing and exporting quantum circuits and ZX-diagrams

There are several ways to import and export circuits and ZX-diagrams in PyZX.

Importing and exporting quantum circuits

There are a number of standards for representing quantum circuits that are supported in PyZX. To see if PyZX supports a certain file format, just call load:

circuit = zx.Circuit.load("path/to/circuit.extension")

The currently supported formats are

  • QASM,

  • the ASCII format of Quipper,

  • the simple .qc format used for representing quantum circuits in LaTex,

  • and the qsim format used by Google.

To convert a PyZX circuit to these formats, use to_qasm, to_quipper, to_qc.

PyZX also offers a convenience function to construct a circuit out of a string containing QASM code using either from_qasm or qasm.

To convert a Circuit into a PyZX Graph (i.e. a ZX-diagram), call the method to_graph.

Importing and exporting ZX-diagrams

A ZX-diagram in PyZX is represented as an instance of Graph. A ZX-diagram can be loaded using the .qgraph format that Quantomatic uses, via from_json. It can be converted into that format using to_json.

Apart from this reversible representation, there are also several one-way translations for exporting ZX-diagrams from PyZX. A graph can be exported to GraphML format using to_graphml. To export a ZX-diagram to tikz for easy importing to Latex, use to_tikz.

Additionally, PyZX diagrams can be directly exported into the applications Tikzit using the tikzit function or edited in Quantomatic using the function edit_graph.

Finally, to display a ZX-diagram in Jupyter call draw and to create a matplotlib picture of the ZX-diagram use draw_matplotlib.

Some ZX-diagrams can be converted into an equivalent circuit. For complicated ZX-diagrams, the function extract_circuit is supplied. For ZX-diagrams that come directly from Circuits, e.g. those produced by calling c.to_graph for a Circuit c, one can also use the static method from_graph, which is more lightweight.