Overhaul diagram drawing

[bryano]

[Strilanc]

Here are some features that I would like diagram drawing to support:

• A common base language between text diagrams, latex diagrams, image diagrams, and 3d diagrams. Users giving useful details with on diagram type in mind should find that they've also made the other diagrams look better.
• Ability to mark subgroups of qubits as "related", e.g. "these qubits are the input into the addition, these other qubits are the target, here are labels for the input group and the target group".
• When groups of qubits are contiguous, put a box around them and use the group label.
• Ability for gates to take complete control of individual diagram types (e.g. show swaps as wires moving in latex).

[bryano]

Is anyone working on "image diagrams"? In a sense, that's what the latex diagrams are. It would be great to have an alternative, because Xy-pic (on which qcircuit is based) can be tricky to get to do what you want it to.

I'm skeptical of the utility of 3D diagrams. They're great to put on a poster or magazine cover, but it's hard to see them being informative for more than a handful of gates. I think it would be better to have a (maybe interactive) 2D diagram that shows the operations in a particular time slice.

[Strilanc]

No, no one is working on the image diagrams or 3d diagrams at the moment.

3d diagrams may be useful for tasks such as finding efficient cuts when optimizing tensor contraction order. They would definitely need to be interactive, with the ability to move the camera.

[bryano]

One first step along these lines would be separating the "text" and "diagram" parts of TextDiagramDrawer. For example, the padding attributes thereof seem specific to text diagrams (at least in they way they're being used now). I think this would more cleanly separate the semantics of the diagram from the rendering. This would involve classes such as the following:

• Diagram would have have content like lines, boxes, text.
• TextRenderer would take a Diagram and spit out a text diagram.
• QCircuitRenderer would do the same for qcircuit diagrams.

[dabacon]

There are a couple parts of this issue that are actionable (qubit labels), and there has been a move to separate out block diagram from text diagram. We can either make this issue track those, or close this an open, but I'm not sure this issue is well defined enough as is.