README.md

Quill is a package for creating quantum circuit diagrams in Typst.

Note, that this package is in beta and may still be undergoing breaking changes. As new features like data types and scoped functions will be added to Typst, this package will be adapted to profit from the new paradigms.

Meanwhile, we suggest importing everything from the package in a local scope to avoid polluting the global namespace (see example below).

• Usage quick introduction
• Cheat sheet gallery for quickly viewing all kinds of gates
• Tequila building (sub-)circuits in a way similar to QASM or Qiskit
• Examples
• Changelog

Basic usage

The function quantum-circuit() takes any number of positional gates and works somewhat similarly to the built-int Typst functions table() or grid(). A variety of different gate and instruction commands are available for adding elements and integers can be used to produce any number of empty cells (filled with the current wire style). A new wire is started by adding a [\ ] item.

#{
  import "@preview/quill:0.5.0": *

  quantum-circuit(
    lstick($|0〉$), $H$, ctrl(1), rstick($(|00〉+|11〉)/√2$, n: 2), [\ ],
    lstick($|0〉$), 1, targ(), 1
  )
}

Plain quantum gates — such as a Hadamard gate — can be written with the shorthand notation $H$ instead of the more lengthy gate($H$). The latter offers more options, however.

Refer to the user guide for a full documentation of this package. You can also look up the documentation of any function by calling the help module, e.g., help("gate") in order to print the signature and description of the gate command, just where you are currently typing (powered by tidy).

Cheat Sheet

Instead of listing every featured gate (as is done in the user guide), this gallery quickly showcases a large selection of possible gates and decorations that can be added to any quantum circuit.

Tequila

Tequila is a submodule that adds a completely different way of building circuits.

#import "@preview/quill:0.5.0" as quill: tequila as tq

#quill.quantum-circuit(
  ..tq.build(
    tq.h(0),
    tq.cx(0, 1),
    tq.cx(0, 2),
  ),
  quill.gategroup(x: 2, y: 0, 3, 2)
)

This is similar to how QASM and Qiskit work: gates are successively applied to the circuit which is then layed out automatically by packing gates as tightly as possible. We start by calling the tq.build() function and filling it with quantum operations. This returns a collection of gates which we expand into the circuit with the .. syntax. Now, we still have the option to add annotations, groups, slices, or even more gates via manual placement.

The syntax works analog to Qiskit. Available gates are x, y, z, h, s, sdg, sx, sxdg, t, tdg, p, rx, ry, rz, u, cx, cz, and swap. With barrier, an invisible barrier can be inserted to prevent gates on different qubits to be packed tightly. Finally, with tq.gate and tq.mqgate, a generic gate can be created. These two accept the same styling arguments as the normal gate (or mqgate).

Also like Qiskit, all qubit arguments support ranges, e.g., tq.h(range(5)) adds a Hadamard gate on the first five qubits and tq.cx((0, 1), (1, 2)) adds two CX gates: one from qubit 0 to 1 and one from qubit 1 to 2.

With Tequila, it is easy to build templates for quantum circuits and to compose circuits of various building blocks. For this purpose, tq.build() and the built-in templates all feature optional x and y arguments to allow placing a subcircuit at an arbitrary position of the circuit. As an example, Tequila provides a tq.graph-state() template for quickly drawing graph state preparation circuits.

The following example demonstrates how to compose multiple subcircuits.

#import tequila as tq

#quantum-circuit(
  ..tq.graph-state((0, 1), (1, 2)),
  ..tq.build(y: 3, 
      tq.p($pi$, 0), 
      tq.cx(0, (1, 2)), 
    ),
  ..tq.graph-state(x: 6, y: 2, invert: true, (0, 1), (0, 2)),
  gategroup(x: 1, 3, 3),
  gategroup(x: 1, y: 3, 3, 3),
  gategroup(x: 6, y: 2, 3, 3),
  slice(x: 5)
)

Examples

Some show-off examples, loosely replicating figures from Quantum Computation and Quantum Information by M. Nielsen and I. Chuang. The code for these examples can be found in the example folder or in the user guide.

Contribution

If you spot an issue or have a suggestion, you are invited to post it or to contribute. In architecture.md, you can also find a description of the algorithm that forms the base of quantum-circuit().

Tests

This package uses typst-test for running tests.

Changelog

v0.5.0

• Added support for multi-controlled gates with Tequila.
• Switched to using context instead of the now deprecated style() for measurement. Note: Starting with this version, Typst 0.11.0 or higher is required.

v0.4.0

• Alternative model for creating and composing circuits: Tequila.

v0.3.0

• New features
  • Enable manual placement of gates, gate($X$, x: 3, y: 1), similar to built-in table() in addition to automatic placement. This works for most elements, not only gates.
  • Add parameter pad to lstick() and rstick().
  • Add parameter fill-wires to quantum-circuit(). All wires are filled unto the end (determined by the longest wire) by default (breaking change ⚠️). This behavior can be reverted by setting fill-wires: false.
  • gategroup() slice() and annotate() can now be placed above or below the circuit with z: "above" and z: "below".
  • help() command for quickly displaying the documentation of a given function, e.g., help("gate"). Powered by tidy.
• Improvements:
  • Complete rework of circuit layout implementation
    • allows transparent gates since wires are not drawn through gates anymore. The default fill is now auto and using none sets the background to transparent.
    • midstick is now transparent by default.
  • setwire() can now be used to override only partial wire settings, such as wire color setwire(1, stroke: blue), width setwire(1, stroke: 1pt) or wire distance, all separately. Before, some settings were reset.
• Fixes:
  • Fixed lstick/rstick when equation numbering is turned on.
• Removed:
  • The already deprecated scale-factor (use scale instead)

v0.2.1

• Improvements:
  • Add fill parameter to midstick().
  • Add bend parameter to permute().
  • Add separation parameter to permute().
• Fixes:
  • With Typst 0.11.0, scale() now takes into account outer alignment. This broke the positioning of centered/right-aligned circuits, e.g., ones put into a figure().
  • Change wires to be drawn all through ctrl(), making it consistent to swap() and targ().

v0.2.0

• New features:
  • Add arbitrary labels to any gate (also derived gates such as meter, ctrl, ...), gategroup or slice that can be anchored to any of the nine 2d alignments.
  • Add optional gate inputs and outputs for multi-qubit gates (see gallery).
  • Implicit gates (breaking change ⚠️): a content item automatically becomes a gate, so you can just type $H$ instead of gate($H$) (of course, the gate() function is still important in order to use the many available options).
• Other breaking changes ⚠️:
  • slice() has no dx and dy parameters anymore. Instead, labels are handled through label exactly as in gate(). Also the wires parameter is replaced with n for consistency with other multi-qubit gates.
  • Swap order of row and column parameters in annotate() to make it consistent with built-in Typst functions.
• Improvements:
  • Improve layout (allow row/column spacing and min lengths to be specified in em-lengths).
  • Automatic bounds computation, even for labels.
  • Improve meter (allow multi-qubit gate meters and respect global (per-circuit) gate padding).d
• Fixes:
  • lstick/rstick braces broke with Typst 0.7.0.
  • lstick/rstick bounds.
• Documentation
  • Add section on creating custom gates.
  • Add section on using labels.
  • Explain usage of slice() and gategroup().

v0.1.0

Initial Release