Cannot visualize PhasedZX gate from squin in tsim_circuit.diagram() #737

[jasonhan3]

I believe @abidart encountered this issue

[rafaelha]

PhasedZX is not currently supported in Tsim - it would have to be represented by a U3 instruction.

Visualization of new gates is tricky: For simplicity, Tsim uses Stim to generate SVGs. Since Stim only supports Clifford gates, the SVGs are then edited, e.g., to replace S with T wherever appropriate.

Gates that are more complicated are hard to visualize. For single-axis rotation gates, it still works:

But for U3 gates, there is usually no space below the gates to add the rotation angles. So Tsim simply omits them

We'd have the same problem for the PhasedZX gate, there is not enough space to cleanly put the three parameters under the gate box.

One potential workaround: use a PAULI_CHANNEL_1 gate (which has a wide box) and modify it to become a PhasedZX