gatefold

Quantum circuit diagram plotting that is:

• Lightweight — the only dependency is matplotlib.
• Adaptable — gatefold can accept any circuit representation. Just write a small adapter converting your package's circuit objects into a list[Layer].
• Sleek — a considered default palette, mathtext labels, auto-fit text, and clean packing.

pip install gatefold
# or
uv add gatefold

Usage

gatefold's whole vocabulary is Item (something drawn on one or more qubit rows) grouped into Layers (packed left-to-right, ASAP, with a barrier between layers).

Labels support matplotlib mathtext, e.g. r"$Z_0 Z_1^\dagger$". Runnable versions of the examples below are in examples/examples.ipynb.

from gatefold import Item, Layer, plot_circuit

layers = [
    Layer(items=[Item(("q0",), "H"), Item(("q1",), "H")]),
    Layer(items=[Item(("q0", "q1"), r"$e^{-i\theta Z_0 Z_1}$")]),
]
ax = plot_circuit(layers)

Items can span more than two rows, and a style key looks up a Palette entry to color-code gates (e.g. by arity):

from gatefold import Item, Layer, plot_circuit, set_clean_rcparams

set_clean_rcparams()  # LaTeX-like typography, call once at import time

layers = [
    Layer(items=[Item(("q0",), "H", style="single"), Item(("q1",), "H", style="single")]),
    Layer(items=[Item(("q0", "q3"), r"$e^{-i\theta Z_0 Z_3}$")]),
    Layer(items=[Item(("q0",), "H", style="single"), Item(("q1", "q2"), "CNOT", style="multi")]),
    Layer(items=[Item(("q2",), r"$R_z(\phi)$", style="single")]),
]
ax = plot_circuit(layers, qubit_display={"q0": "$q_0$", "q1": "$q_1$", "q2": "$q_2$", "q3": "$q_3$"})

Writing an adapter

An adapter is a single function, your_circuit ( + metadata) -> list[Layer]. It's the only place that needs to know about both your package and gatefold. This is what the adapter needs to do:

• For each gate/term in the circuit you input, it must infer three things to construct an Item: which qubits the gate touches (tuple), a label (plain text or mathtext), and a style key.

• Your package likely has methods to look up the first two properties from the gate/term objects the circuit is built from. If not, you need to pass metadata from which they can be inferred.

• style is yours to define. gatefold just uses it to look up a StyleSpec in a Palette you can define. The Palette is a dictionary mapping the "types" of gates you want to the StyleSpec you want to decorate them with. For instance, you might want different styles for gates of different -arity, hardware-native vs. symbolic, etc. The adapter function must be able to infer these types and attach the appropriate style as the third argument of the Item class.

• If your source representation has several sub-types (e.g. hardware gates vs. symbolic terms vs. encoded terms), each branch can have completely different internal logic captured in its own adapter function as long as every branch ends up emitting the same valid list[Layer].

Internals

ARCHITECTURE.md covers the module layout, the packing algorithm, and how text auto-fit keeps large diagrams fast — worth a read before changing the layout or drawing code.

License

MIT