circuit visualization - why should we do a native package

[Roger-luo]

I think we all agree visualization is important for debugging especially for circuits (and perhaps all other levels). While currently, it is possible to create a picture on a given QASM2-compatible kernel program by emitting QASM2 string and read it as a qiskit circuit.

There are certain information get lost between compilation:

• qiskit does not have the noise channels in our implementation and thus cannot visualize the noise channels within circuits to show where does the noise happen
• we cannot annotate blocks of subroutines and the plot end up being inlining everything, for large circuit, this is very hard to read
• because we are compiling things into QASM/qiskit circuit/cirq circuit, these language typically do not have control flow or structures such as a loop repeating some gate, a subroutine call to some stdlib function (e.g phase estimation calling qft as subroutine), it is more nature to visualize these structure directly on our IR

@stefan-o bring up these needs and I think this serves a good motivation to build our native plotting package for circuits on squin.

cc: @stefan-o

[weinbe58]

I've noticed that qiskit does have cf and scf like statements inside their IR but I wonder if they can actually visualize them?

[johnzl-777]

I think this is a great addition to squin and bloqade in general, I always thought it a bit unfortunate that, as you point out, information gets lost when going to other SDKs on TOP of the fact that users will have to "leave" our SDK just to visualize things which makes our work feel more barebones than it really is.

[weinbe58]

In some cases we could support something like this: quantumlib/Cirq#7354 especially if your classical variables are all foldable and the resulting program is static.