quedit

A WYSIWYG editor for quantum circuits that runs in the browser and writes quantikz LaTeX and OpenQASM 2.0 / 3.0, and reads OpenQASM back in.

→ https://quantum.fit.vut.cz/quedit/

No installation, no server, no dependencies: the whole tool is one HTML file that also works offline from file://.

Using it

• Place gates by dragging them from the palette onto a wire, or click a gate to pick it and click on the circuit to place it (Shift-click to place several). Keyboard: h x y z s t pick the gate, m a measurement, c a control, w a swap, b a barrier.
• Controls: drop a ● (or ○ for a negative control) into a column that has a gate — it joins the nearest gate there. CNOT and CZ in the palette come with their control already attached. Any gate can have any number of controls.
• Move a gate by dragging it; drag a control dot or a swap end to move just that end. Drag anything off the circuit (or right-click it) to delete it.
• Edit the selected gate in the side panel: parameters (pi/4, theta, -2*pi/3), target qubits, controls (~2 is a negative control on qubit 2), the classical bit of a measurement, a classical condition. Arrow keys move the selected gate, Del deletes it.
• Output: the bottom pane shows quantikz, OpenQASM 3 and OpenQASM 2, live. The OpenQASM tabs are editable: change the code, or open a .qasm file, and press load into editor (Ctrl+Enter). Parse errors point at their line.
• copy link gives a permalink with the circuit, its layout and the export options in it. See below for why links point at a versioned copy.

quantikz options

• wire labels: q_{0} style register names, \ket{0}, or none.
• measurement: just \meter{}; the wire turning classical after the final measurement; or a classical register wire at the bottom with \vcw from each meter.
• full document: wrap the circuit in a standalone document that compiles on its own.

The output uses only commands present in quantikz 1.0 (TeX Live 2023) and compiles with newer versions too.

What is supported

gates	id h x y z s sdg t tdg sx sxdg rx ry rz p u u2 swap rxx ryy rzz, plus any named box over any number of qubits
modifiers	any number of positive/negative controls on any gate; inv @ (folded into the gate where possible); pow(k) @ is kept
other	measure, reset, barrier, if (…) conditions
OpenQASM import	2.0 (qreg, creg, qelib1.inc gates incl. Qiskit's additions) and the matching subset of 3.0 (qubit[n], bit[n], c = measure q, ctrl(n)/negctrl/inv/pow @, stdgates.inc); register broadcasting; gate/opaque definitions are kept and re-emitted
not supported	classical control flow (for, while, def), classical expressions beyond conditions, pulse-level code

Known limitations: a barrier on a subset of qubits becomes a full-height \slice in quantikz; a multi-qubit box over non-adjacent wires is drawn over the wires between them (the editor numbers the box's wires in that case); classically conditioned gates are drawn without their condition in quantikz (a comment in the output says so). Things OpenQASM 2 cannot express (e.g. rx with two controls) are reported and left as comments.

Import from quantikz is not supported yet.

Developing

python3 -m http.server 8000      # then open http://localhost:8000/dev.html
node --test tests/*.test.js      # zero dependencies; compiles the LaTeX if pdflatex is around
node tools/build.mjs             # the single-file quedit.html

dev.html loads the ES modules in src/ directly; there is no build step in the dev loop. Only src/editor.js and src/ui.js touch the DOM — the circuit model, the OpenQASM parser and the exporters run headless in Node, which is what the tests use.

module	role
src/model.js	the circuit: registers and a grid of columns of operations
src/qasm.js	OpenQASM 2/3 parser and writer
src/quantikz.js	quantikz writer
src/links.js	permalinks and versioned URLs
src/editor.js	the SVG canvas and drag and drop
src/ui.js	the rest of the page

Versions, previews and links

Done the same way as in q-vis:

• the site root is master, and master only moves on a release tagged v1, v2, …;
• every release is kept, frozen, at /v/<tag>/ (listed at /v/), and copy link in a released build points there, so a shared link keeps opening the editor that made it;
• the preview branch is published at /preview/ for review before a release: git push -f origin HEAD:preview.

Details in docs/VERSIONS.md.

License

MIT.